Lipoprotein Lipase Activity in Skeletal Muscle Is Related to Insulin Sensitivity. T. Pollare, B. Vessby, and H. Lithell

Transcription

1 1192 Lipopotein Lipase Activity in Skeletal Muscle Is Related to Insulin Sensitivity T. ollae, B. Vessby, and H. Lithell Downloaded fom by on Decembe 13, 2018 The elative effects of obesity, alone o in combination with insulin esistance and hypeinsulinemia (with o without diabetes), on lipopotein concentations, blood pessue, and othe isk factos fo cadiovascula disease wee investigated in 28 men (mean age, 63 yeas). Special attention was given to lipopotein lipase (LL) activity in tissues and to posthepain plasma LL activity and hepatic lipase activity and thei elation to insulin esistance. The 28 men fulfilled the entance citeia of the study so that they could be allocated to one of the fou goups (seven in each goup): 1) nomal body weight, nomal fasting insulin level, and nomal glucose toleance (contols); 2) the same as in goup 1 but with modeate obesity; 3) the same as in goup 2 but with fasting hypeinsulinemia; 4) the same as in goup 3 but with non-insulin-dependent diabetes mellitus. Glucose infusion ate fo the contol goup was 8.1±2.1 mg/kg body wt/min (mean±sd) at an insulin infusion ate of 56 milliunits/m 2 /min. The aveage values in goups 2, 3, and 4 wee 6.0±0.7, 3.2±0.5, and 1.9±1.0 mg/kg body wt/min, espectively. Concentations of vey low density lipopoteins as well as blood pessue and uate concentations wee highest and those of high density lipopoteins wee lowest in the two hypeinsulinemic goups (goups 3 and 4). Skeletal muscle LL activity was 46 ±23,41 ±25, 23 ±6, and 31 ±13 milliunits/g wet wt (mean±sd) in the fou goups, espectively. Thee was a positive coelation between glucose infusion ate and muscle LL activity (=0.58,/?<0.0001). The hepatic lipase activity was positively coelated with the insulin aea unde the cuve of the intavenous glucose toleance test (=0.35, p=0.02). Futhemoe, blood pessue, fee fatty acid concentation, live enzymes, and uate concentations wee significantly coelated with glucose infusion ate at the clamp test. These data give futhe suppot fo insulin esistance as an impotant facto behind the obseved lipopotein abnomalities and blood pessue elevations as pat of the insulin esistance syndome chaacteistic fo obese and diabetic patients. (Ateioscleosis and Thombosis 1991;ll: ) Insulin esistance has been descibed as the common undelying mechanism that causes much of the hypetension, dyslipidemia, and impaied glucose toleance in the population. 12 Elevated levels of tiglyceide (TG)-ich lipopoteins ae a chaacteistic of diabetes mellitus and impaied glucose toleance. 3 A deceased capacity fo elimination of TGs may well play a ole in the development of hypetiglyceidemia, 4 but the possible undelying mechanisms have only patly been studied. Fom the Depatment of Geiatics, Uppsala Univesity, Uppsala, Sweden. Suppoted by gants fom the Medical Faculty at Uppsala Univesity, the Swedish Medical Reseach Council (gant No. 5446), the Swedish Diabetes Association, The Enfos Fund fo Diabetes Reseach, the King Gustaf V Fund, the Heat and Lung Fund, Foenade Liv Mutual Life Insuance Copoation, and the Swedish Society of Medicine. Addess fo coespondence: ofesso Hans Lithell, Depatment of Geiatics, Uppsala Univesity, O Box 2151, S Uppsala, Sweden. Received Novembe 7, 1989; evision accepted Apil 24, To ensue the uptake of fatty acids fom the TG-ich lipopoteins in the ciculation, the enzyme lipopotein lipase (LL) is pesent in the endothelial wall of the capillaies in most tissues of the body 5 as well as in the endothelium of lage ateies. LL activity is a ate-limiting facto in TG uptake and consequently has a key function in the egulation of the concentations of TG-ich lipopoteins in the ciculation. 5 In a ecent study we epoted that in fou goups of men chaacteized by 1) nomal body weight and nomal insulin concentation, 2) obesity and nomal insulin concentation, 3) obesity and hypeinsulinemia, o 4) obesity and non-insulin-dependent diabetes mellitus (NIDDM), adipocytes wee not chaacteized by insulin esistance except fo those fom the diabetic men. 6 This finding indicated that insulin esistance must pevail in tissues othe than adipose tissue because seum insulin concentations wee inceased in goup 3. Futhemoe, LL activity in adipose tissue did not diffe among the fou goups

2 ollae et al LL Activity and Insulin Sensitivity 1193 TABLE 1. Vaiable Selected Vaiables fo the Study opulation Body mass index (kg/m 2 ) Waist to hip atio Fasting glucose concentation (mmol/1) Fasting insulin concentation (milliunits/1) HbA lc (%) Intavenous glucose toleance (%/min) Glucose infusion ate (mg/kg body wt/min/milliunitxloo) Nomal-weight contol 24.0± ± ± ± ± ± ±2.9 Subgoup nomoinsulinemic 30.1 ±2.5* 0.93 ± ± ± ± ± ±1.6* hypeinsulinemic 31.7± ± ± ±4.8t 4.7 ± * diabetic 30.4±2.6* 0.99± ±2.7* 19.1 ±8.3* 6.9±1.8f 0.5 ±0.2* 1.5 ±0.6* Values ae mean±sd fo selected vaiables in the fou subgoups (n = 7 in each goup). Compaisons wee made between the obese goups and the nomal-weight nomoinsulinemic men. HbA lc, the glycosylated fom of the majo component of adult hemoglobin faction Ai. *p<0.05, t/»<0.01, *p< Downloaded fom by on Decembe 13, 2018 and thus could not explain the diffeence in TG levels that existed among the goups. In othe studies it was found that muscle LL activity was invesely elated to body weight and seum insulin concentation 7 and was lowe in diabetic than in nomoglycemic pesons. 8 This finding may indicate that muscle LL activity is elated to insulin esistance and that low muscle LL activity may be pat of the explanation fo elevated TGs in diabetes and obesity. Theefoe, the pimay aim of the pesent study was to investigate to what extent goups of men with widely diffeing body weight and insulin and glucose concentations diffeed with egad to lipopotein concentations and thei dependence on LL activity, as expessed not only in muscle tissue but also in adipose tissue, and LL activity and hepatic lipase activity in plasma afte hepain injection. Because insulin concentations do not eflect the degee of insulin esistance in diabetic patients, a euglycemic hypeinsulinemic clamp test was included to futhe elucidate the elations between insulin esistance and cabohydate and lipopotein metabolism. Othe aims of the study wee to ecod blood pessue, glucose toleance, live enzymes, and uate levels in blood plasma; to investigate whethe the goups diffeed in these espects; and to detemine to what extent any diffeences wee elated to insulin concentations and insulin esistance. Methods Subjects A total of 28 men wee selected fo the pesent study; subjects wee dawn mainly fom a lage health suvey (with 2,300 male paticipants) in Uppsala, a medium-sized town in Sweden. In about 1,600 of these subjects, an intavenous glucose toleance test (IVGTT) had been pefomed. The majoity of the 28 men had been investigated some yeas ago. 6 The men wee selected so as to fit into one of fou categoies: 1) men of nomal weight (body mass index [BMI, weight {kg} divided by height squaed {m 2 }]<27), nomal intavenous glucose toleance, and nomal fasting insulin concentation; 2) modeately obese men (BMI >27) with nomal fasting glucose and intavenous glucose toleance and a fasting insulin concentation simila to that in the nomal-weight goup (within the mean+3sds of the nomal goup); 3) men with modeate obesity and nomal glucose toleance but with a fasting insulin concentation above the mean+3sds of that in the nomal-weight subjects; 4) men with modeate obesity and NIDDM (fasting blood glucose >7 mmol/1) and with fasting insulin concentations above the mean+3sds of the contol goup. Seven men wee allocated to each goup. The clinical chaacteistics of these study goups ae pesented in Table 1. Twelve wee smokes, who wee distibuted in all fou goups. Thee was no significant diffeence in physical activity among the goups accoding to a fou-point scale. 9 All paticipating subjects wee fee fom othe diseases, as detemined by medical histoy and a thoough physical examination, and wee not being teated with any dugs. Thee was no clinical o laboatoy evidence of hepatic, enal, o thyoid dysfunction. Infomed consent was obtained fom all subjects afte the natue, pupose, and possible side effects of the study had been fully explained. The study potocol was appoved by the Ethics Committee of the Univesity Hospital of Uppsala. Expeimental ocedue All subjects wee ambulatoy at the time of thei examination in the outpatient depatment of the hospital, which took place at 8 AM afte an ovenight (12-hou) fast. Thei mean age was 63 yeas, anging fom 56 to 67 yeas. Adipose and muscle tissue biopsies, an intavenous fat toleance test (IVFTT), and an IVGTT wee pefomed, and posthepain plasma lipolytic activity and insulin sensitivity wee evaluated on fou sepaate

3 1194 Ateioscleosis and Thombosis Vol 11, No 5 Septembe/Octobe 1991 Downloaded fom by on Decembe 13, 2018 days, with an inteval of 2-3 days between each investigation. Dietay histoy had evealed a fat intake of 32-38% of enegy and of cabohydates of 42-52% of enegy. 6 Fo this paticula study each paticipant was instucted to adhee to his egula diet but to maintain an intake of at least 250 g cabohydates daily and to efain fom exteme physical execise o inactivity fo at least 5 days befoe the investigation. Smokes wee instucted not to smoke on the moning of the investigation. No othe instuctions egading diet o execise wee given duing the study. Blood samples wee dawn, and uine specimens wee collected afte an ovenight (12-hou) fast. Blood pessue and heat ate. Blood pessue was measued by mecuy sphygmomanomety thee times in the supine position afte a est of 10 minutes and twice afte 1 minute of standing. The mean of each of these sets of values was used in the analyses. A lage cuff was used when appopiate. The pulse ate was ecoded befoe each blood pessue measuement. Intavenous glucose toleance test. The IVGTT was pefomed, as ecently descibed in detail, 10 by injection of 300 mg glucose/kg body wt. lasma glucose was measued by the glucose oxidase method. Immunoeactive insulin was assayed in plasma by use of a commecial adioimmunoassay kit (hadeseph Insulin RIA, hamacia, Uppsala, Sweden). Glucose toleance was expessed as the k value, as descibed by Ikkos and Luft. 11 The peak insulin esponse was defined as the mean of the values obtained at 2, 4, and 6 minutes, and the insulin index was defined as the atio between the peak and basal plasma insulin values (mean of values at 10, -5, and 0 minutes). The aeas unde the cuves fo glucose and insulin duing the IVGTT wee calculated as the deviations fom the basal value integated ove the sampling time. The aveage fasting plasma insulin and glucose concentations wee calculated fom fou samples taken on two sepaate days. The glycosylated fom of the majo component of adult hemoglobin faction A, (HbA lc ) was measued by fast-pefomance liquid chomatogaphy (nomal ange, %). 12 Clamp studies. The euglycemic hypeinsulinemic clamp technique, as intoduced by DeFonzo et al, 13 was used and has ecently been descibed in detail. 10 The insulin (Actapid, Human, Novo, Denmak) infusion ate was 56 milliunits/m 2 /min in all subjects, esulting in a mean plasma insulin concentation of 102 milliunits/1 (ange, milliunits/1) duing the clamp studies. The taget level of plasma glucose duing the clamp study was 5.3 mmol/1, and this level was maintained by measuing plasma glucose (Beckman Glucose Analyze II, Beckman Instuments, Fulleton, Calif.) evey 5 minutes and adjusting the infusion ate of the 20% glucose solution accodingly. In all diabetics the desied plasma glucose level was attained within 60 minutes fom the stat of the insulin infusion, except in two diabetic patients in whom the clamp test was pefomed at a glucose level of about 5.7 mmol/1. Thei esults ae included in all calculations. Unde steady-state conditions of euglycemia, the glucose input (consisting of exogenous glucose infusion and endogenous glucose poduction) must equal the glucose use by all tissues of the body. Endogenous (hepatic) glucose poduction was quantified in pesons fom all fou goups. Clamp studies wee then pefomed in combination with titiated D-glucose (D[3-3 H]glucose) to measue the effect of hypeinsulinemia on hepatic glucose poduction. The piming dose was 40 /ici fo diabetic patients and 20 p,ci fo nomal subjects, and it was given as a 20-ml bolus injection. The continuous infusion povided 0.40 /nci/min fo diabetic patients and 0.20 /ici/min fo nomal subjects. The duation of the D[3-3 H]glucose insulin befoe the stat of insulin infusion was 120 minutes in nomal subjects and 180 minutes in diabetic patients. lasma samples fo detemination of D[3-3 H]glucose specific activity wee obtained evey 5 minutes duing the last 30 minutes of the equilibation peiod, afte which time the insulin infusion was begun. A steady state of glucose-specific activity was achieved by this method in each subject. Duing the insulin clamp study plasma samples fo D[3-3 H]glucose specific activity wee obtained at 15-minute intevals until the last 30 minutes, at which time they wee obtained at 5-minute intevals. D[3-3 H]glucose activity was detemined afte depoteinization with Ba(OH) 2 -ZnSO 4 and evapoation of wate. 14 The specific activity of glucose was calculated by dividing the D[3-3 H]glucose activity by the plasma glucose concentation. D[3-3 H]glucose (5 Ci/mmol) was puchased fom The Radiochemical Cente, Amesham, England. Lipopotein and Lipid Analyses TG and cholesteol concentations in seum and lipopoteins wee detemined by enzymatic methods (Boehinge Mannheim, Mannheim, FRG) in a Multistat III F/LS (Instumentation Laboatoies, Lexington, Mass.). The analytical eos fo the two methods wee 1.4% and 1.7%, espectively. Vey low density lipopoteins (VLDLs) wee sepaated by ultacentifugation at a density of g/ml. An MgCyphosphotungstic acid technique was applied to pecipitate low density lipopoteins (LDLs) fom the bottom faction afte ultacentifugation. 15 The supenatant (high density lipopotein, HDL) was analyzed fo its contents of TG and cholesteol. HDL subclass 3 (HDL3) was sepaated fom othe lipopoteins by ultacentifugation of seum at a density of g/ml. The cholesteol and TG concentations wee measued in HDL3 (d> g/ml), and the contents of these lipids in HDL2 wee calculated as the diffeence between those in total HDL and HDL3. The lipid concentations in LDL wee calculated as the diffeence between those in the bottom faction afte ultacentifugation at a density of g/ml and those in HDL. Seum fee fatty acids (FFAs) wee detemined by an enzymatic coloimetic method supplied in a commecial kit (Wako Chemicals GmbH, Neuss, FRG) adapted fo analysis

4 Downloaded fom by on Decembe 13, 2018 in the Multistat III centifugal analyze. Fee glyceol was measued with a TG kit (Boehinge Mannheim), with omission of the saponification step afte adaptation fo use in the Multistat III. Analyses of Lipopotein Lipase Activities and the Intavenous Fat Toleance Test Specimens of subcutaneous adipose tissue wee obtained fom the egion lateal to the umbilicus (abdominal site) by use of the technique descibed by Hisch and Goldick. 16 Biopsy samples of skeletal muscle tissue wee taken fom the lateal vastus muscle with an instument descibed by Begstom. 17 The tissue samples wee stoed in liquid N 2 until analyzed. Each sample was weighed in the fozen condition and then incubated in a eaction medium based on a glycine buffe (2.1 mol/1, ph 8.4) containing hepain (240 IU/ml), a tiolein-phospholipid emulsion, 18 albumin (7.5 mg/ml), and seum (3%). The pocedues have been descibed in detail elsewhee. 19 " 21 The activity is expessed in milliunits (1 milliunit=l nmol fatty acid eleased/min) pe gam wet weight of tissue. lasma samples fo detemination of lipase activities wee dawn 40 minutes afte intavenous administation of 100 IU hepain (KabiVitum, Stockholm, Sweden) pe kilogam body weight. 22 The activities of hepatic lipase and LL wee detemined by specific methods, with the use of glyceol ti[9,10(n)- 3 H]oleate as the substate All samples wee stoed at -70 C befoe analysis. The elimination ate of exogenous TG was detemined by the IVFTT, as descibed by Calson and Rossne, 2526 with injection of 1 ml 10% Intalipid (KabiVitum) pe kilogam body weight. Routine Hematology, Biochemisty, and Uinalysis All othe tests (sedimentation ate, hemoglobin concentation, white blood cell count, platelet count, aspatate aminotansfease [ASAT], alanine aminotansfease [ALAT], glutamyltansfease [GT], electolyte balance, albumin, ceatinine, uate concentation in seum, and outine uinalysis) wee pefomed at the Depatment of Clinical Chemisty of the Univesity Hospital, Uppsala. Calculations The total amount of glucose infused seves as a measue of the subject's sensitivity to the pevailing plasma insulin concentation. The glucose infusion ate duing the glucose clamp test is expessed pe kilogam of body weight and adjusted fo the mean insulin concentation duing the clamp test (mg glucose/kg body wt/min/milliunit/lxl00). 13 The calculation of insulin sensitivity is based on the assumption that endogenous hepatic glucose poduction is entiely suppessed (see "Results"). Uinay glucose losses wee negligible unde euglycemic conditions. Hepatic glucose poduction in the basal state (the last 30 minutes of the pe-insulin-infusion peiod) was calculated by dividing the ate of D[3-3 H]glucose infusion (cpm/min) by the steady-state ollae et al LL Activity and Insulin Sensitivity 1195 level of glucose specific activity (dpm/mg). Duing the glucose and insulin infusions when glucose kinetics wee not in a steady-state condition, the glucose appeaance ate was calculated fom Steele's equations in thei deivative fom, with a value of 0.65 fo the pool faction. The ate of endogenous (hepatic) glucose poduction was estimated by subtacting the exogenous glucose infusion ate fom the total body glucose appeaance ate, as calculated by the isotopic tace technique Statistical Analyses Data ae pesented as mean±sd. An analysis of vaiance was pefomed, and all statistical compaisons among the fou goups wee calculated with Tukey's studentized ange test. eason coelation coefficients wee calculated. A stepwise egession analysis (maximum R 2 impovement method) was executed fo some dependent vaiables, fo example, posthepain plasma LL and hepatic lipase activity and LL activity in muscle and adipose tissue, with insulin sensitivity measues, insulin and glucose values, and anthopometic data as independent vaiables. In othe seies diffeent lipopotein and lipid concentations wee used as dependent vaiables, and the lipase activities wee used as independent vaiables. Results The BMI and waist to hip atio wee significantly inceased in all the obese study goups compaed with the nomal-weight contols. In the goups of obese diabetic subjects, a significant incease in the fasting glucose concentation and HbA lc value and a eduction in glucose toleance wee noted (Table 1). The fasting insulin levels in the obese hypeinsulinemic and the obese diabetic goups did not diffe fom one anothe (p=0a5) but wee significantly highe than in the othe goups (/?<0.001) (Table 1). Blood pessue, both systolic and diastolic, in both the supine and standing positions was highest in the obese hypeinsulinemic goup (Table 2). As shown in Table 3, thee was a gadual incease in the cholesteol concentation in the VLDL faction and a decease in the HDL faction fom the contol goup to the obese diabetic goup. The TG concentations in seum, VLDL, HDL, and HDL3 wee significantly inceased in both the obese hypeinsulinemic and the obese diabetic goup compaed with the contol goup (p<0.05). The FFA and plasma glyceol concentations in plasma wee significantly highe in the obese diabetic goup than in all the othe goups (Table 3). Results of Clamp Tests Duing the euglycemic hypeinsulinemic clamp test, plasma glucose was kept constant (mean fo all subjects, mmol/i, close to the chosen level and with a coefficient of vaiation of 3.9 ±1.1%), and thee was no significant diffeence among the goups (

5 1196 Ateioscleosis and Thombosis Vol 11, No 5 Septembe/Octobe 1991 TABLE 2. Vaiable SB supine SB standing DB supine DB standing HR supine HR standing Blood essue Measuements Nomal-weight contol ±18 79±7 79±10 64±11 70±ll fo the Study opulation Subgoup nomoinsulinemic 142±16 139±14 82±9 85 ±6 69±6 74±8 hypeinsulinemic 149±13 152±14t 97±6* 99± ±8 79±5 diabetic 145±11 144±llf 87±7 92±8* 71±8 82±9* Values ae mean±sd fo systolic (SB) and diastolic (DB) blood pessue (mm Hg) and heat ate (HR, beats/min) in the supine and standing positions fo the fou subgoups (n=7 in each goup). Fo statistics, see footnote to Table 1. The steady-state levels of insulin that wee eached duing the euglycemic clamp test eflect the metabolic cleaance ate of insulin. In ou study as in othes, 29 the mean steady-state insulin concentations wee highe in the obese hypeinsulinemic and diabetic goups (116±15 and 124±20 milliunits/1, espectively) than in the nomoinsulinemic goups (85±15 and 87±18 milliunits/1, espectively), which is consistent with a lowe ate of metabolic insulin cleaance in the two hypeinsulinemic goups. To evaluate the degee to which hepatic glucose poduction was inhibited with the pesent hypeinsulinemic clamp pocedue in this kind of subject, we studied hepatic glucose levels in two epesentatives fom each goup. The hepatic glucose output duing the last hou of the clamp study and the pecentage suppession of hepatic glucose poduction ae shown fo each goup sepaately. In nomal-weight contols (n=2), these values wee 2.02±0.15 and 0.11±0.04 mg/kg body wt/min and 95%, espectively; in the obese nomoinsulinemic goup (n=2), 2.29±0.10, 0.14±0.04, and 94%; in the obese hypeinsulinemic goup (n=2), 2.62±0.20, 0.20±0.03, and 92%; and in the obese diabetic goup (n=3), 2.87±0.10,0.34±0.02, Downloaded fom by on Decembe 13, 2018 Vaiable Cholesteol (mmol/l) Seum VLDL chol LDL chol HDL chol HDLj chol HDL, chol Tigfyceides (mmol/l) Seum VLDLTG LDLTG HDLTG HDL2TG HDL3TG lasma FFA lasma glyceol 5.53± ± ± ± ± ± ± ± ± ± ± TABLE 3. Seum Lipid Values fo the Study opulation Subgoup Nomal-weight contol nomoinsulinemic 5.87± ± ± ± ± ± ± ± ± ± ± ± ± ±0.05 hypeinsulinemic 5.76± ±0.59* 3.94± ±0.16* 0.25± ± ±1.21* 2.05±0.92* 0.53 ± ±0.09* 0.09± ±0.04* 0.50± ±0.02* diabetic 5.88± ±0.56* 4.01 ± ± ± ± ±1.28* 2.17±1.26* 0.54± ±0.07* 0.08 ± ±0.08t 0.82 ±0.24* 0.20±0.03* Othe vaiables Uate ALAT GT 333 ± ± ± ± ± ± ±0.21* 0.60± ± ±0.8t 0.71 ±0.26* Values ae mean±sd fo seum lipopotein, plasma fee fatty acid, plasma fee glyceol, and uate concentations and fo ALAT and GT enzyme activities fo the fou study goups (n=7 in each goup). Fo statistics, see footnote to Table 1. VLDL, vey low density lipopotein; chol, cholesteol; LDL, low density lipopotein; HDL, high density lipopotein; TG, tiglyceides; FFA, fee fatty acids; ALAT, alanine aminotansfease; GT, glutamyltansfease.

6 Downloaded fom by on Decembe 13, 2018 Insulin sensitivity index f * * _ 1 * * 4 II % FIGURE 1. Ba gaph showing glucose infusion ate (mg/kg body wt/min/milliunitxloo; adjusted fo pevailing insulin concentation) duing the last hou of the clamp test in the fou study goups: 1) nomal-weight, nomoinsulinemic, nomoglycemic contol goup; 2) obese, nomoinsulinemic, nomoglycemic goup; 3) obese, hypeinsulinemic, nomoglycemic goup; and 4) obese, hypeinsulinemic diabetic goup. **p<0.0i; ***p< and 88%. This finding indicates that duing the last hou of the insulin clamp test, wee thee not only slight diffeences among the fou goups with egad to hepatic glucose poduction but also that it was suppessed to as much as 88% in the most esistant goups, vey simila to the 95% suppession in the contol goup. Hepatic glucose poduction was thus inhibited to a lage extent in all the men tested. Howeve, we do not know the degee of hepatic glucose inhibition in all subjects, and theefoe we 70 _ 60 i ollae et al LL Activity and Insulin Sensitivity 1197 descibe the esults in tems of glucose infusion ate in all cases adjusted fo the pevailing insulin concentation duing the test. Duing the euglycemic hypeinsulinemic clamp test the glucose infusion ate duing the last hou of the clamp test was significantly (/><0.01) deceased in all goups of obese men compaed with the nonobese goup. This was also the case afte adjustment fo the pevailing insulin concentation (in contols, 9.7±2.9 mg/kg body wt/min/milliunit/ 1x100; in obese nomoinsulinemic men, 6.8±1.7; in obese hypeinsulinemic men, 2.8 ±0.6; and in obese diabetics, 1.5±0.7) (Figue 1). Expession of the glucose infusion ate pe squae mete of body suface aea did not change the main findings. The obese hypeinsulinemic goup had significantly (p<0.001) inceased fasting, peak, and late insulin values duing the IVGTT compaed with the othe goups (Figue 2). The aea unde the cuve fo insulin duing the IVGTT was moe than twice as lage (4,412;p<0.001) in the obese hypeinsulinemic goup as in the othe goups (in contols, 898; in obese nomoinsulinemics, 1,933; in obese diabetics, 1,048). The obese diabetic goup showed inceased fasting plasma insulin values (p<0.001) and significantly lowe peak insulin values in esponse to a glucose load but inceased plasma insulin at the end of the IVGTT compaed with the nomoinsulinemic goups (Figue 2). Lipopotein Lipase Activities and Intavenous Fat Toleance The posthepain plasma LL and hepatic lipase activities did not diffe significantly among the goups. Thee was a gadual decease fom the contol Time (minutes) SO 60 Time (minutes) FIGURE 2. lasma insulin (mull; left panel) and glucose (mmolll; ight panel) esponse cuves duing an intavenous glucose toleance test in the fou study goups: 1) nomal-weight, nomoinsulinemic, nomoglycemic contol goup; 2) obese, nomoinsulinemic, nomoglycemic goup; 3) obese, hypeinsulinemic, nomoglycemic goup; and 4) obese, hypeinsulinemic diabetic goup. *p<0.05; **p<0.07; ***p<0.00i.

7 1198 Ateioscleosis and Thombosis Vol 11, No 5 Septembe/Octobe 1991 TABLE 4. Lipase Activity Values fo the Study opulation Vaiable H HL activity (n=27) H LL activity! (n=27) Muscle LL activity! (n=26) Adipose tissue LL activity! (n=26) k 2 duing IVFTT (%/min) (/i=27) Nomal-weight contol ± ±2.4 Subgoup nomoinsulinemic 10.1± ± ± ±37 3.8±1.3 hypeinsulinemic 11.8± ±2.2 23±6* 100± diabetic 8.8± ±2.0 31±13 96±34 2.7±0.8 Values ae mean+sd fo posthepain plasma (H) lipopotein lipase (LL) activity, hepatic lipase (HL) activity, and lipopotein lipase (LL) activity in muscle and adipose tissue and fo the k 2 value duing the intavenous fat toleance test (IVFTT) in the fou subgoups. Fo statistics, see footnote to Table 1. t Activity is expessed in milliunits (1 milliunit/1 = 1 nmol fatty acid eleased/min) pe gam wet weight of tissue o pe millilite plasma. Downloaded fom by on Decembe 13, 2018 goup to the obese hypeinsulinemic goup fo posthepain LL activity, skeletal muscle LL activity, and k 2 value and a gadual incease fo posthepain hepatic lipase activity (Table 4). Howeve, the diabetic goup had not deteioated moe in any of these vaiables than the obese hypeinsulinemic goup. osthepain lasma Hepatic Lipase Activity Hepatic lipase activity was stongly negatively coelated with LDL TG (=0.58, p=0.001) and also with the TG concentation in HDL and HDL3 (Table 5). Hepatic lipase activity was positively coelated with the insulin aea unde the cuve duing the IVGTT(=0.41,p=0.03). osthepain lasma Lipopotein Lipase Activity LL activity in posthepain plasma was invesely coelated with TG concentation in seum and VLDL and positively with HDL3 cholesteol concentation (Table 5). In a stepwise egession model, 51% of the vaiation in posthepain plasma LL was explained, the lagest contibutions coming fom the glucose infusion ate duing the clamp test (patial R 2 =l9%) and fasting blood glucose concentation (patial R 2 =14%). Lipopotein Lipase Activity in Adipose Tissue Adipose tissue LL activity was not significantly coelated with any lipopotein lipid vaiable (Table 5). It was negatively coelated with HbAi c (= -0.32, p=0.033). Lipopotein Lipase Activity in Skeletal Muscle Muscle LL activity was negatively coelated with TG concentations in seum and VLDL and positively with LDL cholesteol concentation and intavenous fat toleance (Table 6). Muscle LL activity was positively coelated with the glucose infusion ate duing the clamp test (Table 6 and Figue 3) and negatively with insulin concentation (Figue 4), ALAT, GT, and uate. In a stepwise egession model, 42% of the vaiation in muscle LL activity was explained by the glucose infusion ate (patial R 2 =28.5%) and fasting glucose concentation (patial i? 2 =13.5%). When these measues wee accounted fo, the addition of othe vaiables did not contibute significantly to an impovement in the degee of explanation, indicating, fo example, that uate concentation, blood pessue, ALAT, and GT (Table 6) wee not diectly elated to muscle LL activity but to glucose infusion ate (see below). Neithe did the addition of seum TG concentation as an independent vaiable contibute significantly (p>0.6) to the model in the pesence of glucose infusion ate and fasting insulin concentation. Factional Removal Rates The k 2 values of the IVFTT wee negatively coelated with the seum TG. The k 2 value was positively coelated with glucose infusion ate duing the clamp test and skeletal muscle LL activity (Table 6). A stepwise egession analysis was pefomed with k 2 as the dependent vaiable and LL activities as the independent vaiables. Twenty-six pecent of the vaiation in k 2 was explained by skeletal muscle LL activity. No othe lipase activity impoved the degee of explanation significantly. Howeve, when glucose infusion ate was added, the degee of explanation inceased significantly to 39%. Seum Tiglyceides Seum TG levels wee invesely coelated with posthepain plasma LL and skeletal muscle LL activities and with glucose infusion ate duing the clamp test (Table 5) and positively with ALAT (Table 6). A stepwise egession analysis was pefomed, with seum TG as the dependent vaiable and the diffeent LL activities, hepatic lipase activity, FFA concentation, and glucose infusion ate duing the clamp test as the independent vaiables. Thity-five pecent of the vaiation in seum TG was explained by LL activity in posthepain plasma, LL activity in muscle tissue, and hepatic lipase activity, but when the effect of these vaiables was accounted fo, neithe adipose tissue LL activity no FFA concentation contibuted significantly to an impovement in the degee of explanation.

8 ollae et al LL Activity and Insulin Sensitivity 1199 TABLE 5. Coelation Coefficients Between Seveal Vaiables fo the Study opulation Downloaded fom by on Decembe 13, 2018 Vaiable Seum TG VLDLTG VLDL chol LDLTG LDL chol HDLTG HDL chol HDL 3 TG HDL 3 chol HDL-2 chol H LL activity H HL activity Muscle LL activity Coelation coefficients () between some vaiables fo the study population (n=28). Statistical significance is indicated below each value. H, posthepain plasma; LL, lipopotein lipase; HL, hepatic lipase; AT, adipose tissue; TG, tiglyceides; VLDL, vey low density lipopotein; chol, cholesteol; LDL, low density lipopotein; HDL, high density lipopotein. Fee Fatty Acids Levels of FFAs wee significantly invesely coelated with glucose infusion ate and positively with HbA, c, ALAT, and GT values (Table 6). The mean value in the diabetic goup was significantly highe than in the othe thee goups. Diastolic Blood essue Diastolic blood pessue was significantly positively coelated with insulin concentation and invesely with glucose infusion ate duing the clamp test (Table 6). Fifty-two pecent of the inteindividual vaiation of diastolic blood pessue taken while subjects wee in the supine position was explained by thee factos togethe: insulin at 90 minutes (patial R 2 =34%), glucose infusion ate (patial R 2 =6%), and the k value at the IVGTT (patial R 2 =12%) AT LL activity Seum Alanine Aminotansfease and Glutamyltansfease Concentations Seum ALAT and GT concentations wee highest in the obese hypeinsulinemic goup. The obese diabetic men (ALAT of 0.66±0.08 ;umol) and the obese hypeinsulinemic men (ALAT of 0.73 ±0.21 )u,mol) had highe values than the othe goups (p<0.001). The ALAT values wee stongly invesely elated to the glucose infusion ate (Table 6 and Figue 5). The obese hypeinsulinemic goup had the highest seum uate concentation (434±155 yu,mol/l). Discussion Hypetension, obesity, and impaied glucose toleance often appea togethe in diffeent combinations 230 and also with lipopotein abnomalities, in paticula hypetiglyceidemia in combination with

9 1200 Ateioscleosis and Thombosis Vol 11, No 5 Septembe/Octobe 1991 TABLE 6. Coelation Coefficients Between Seveal Vaiables fo the Study opulation Downloaded fom by on Decembe 13, 2018 Vaiable ALAT GT HbA lc Uate k 2 (IVFTT) Seum insulin (t=0) Glucose infusion ate BMI Muscle LL activity k 2 (IVFTT) Seum TG lasma FFAs Seum ALAT DB WHR Coelation coefficients () between some vaiables fo the study population. Statistical significance is indicated below each value. LL, lipopotein lipase; IVFTT, intavenous fat toleance test; TG, tiglyceides; FFAs, fee fatty acids; ALAT, alanine aminotansfease; DB, diastolic blood pessue; GT, glutamyltansfease; HbA lc, the glycosylated fom of the majo component of adult hemoglobin faction A!; BMI, body mass index; WHR, waist to hip atio. low HDL cholesteol. 30 It has been ecently suggested that hypeinsulinemia is a common denominato fo hypetension, obesity, and impaied glucose toleance. 2 Hypeinsulinemia is the eflection and consequence of an insulin-esistant state except fo the diabetic condition, in which insulin secetion does not match the ponounced insulin esistance and "nomal" o low insulin concentation may pevail. 1 The insulin-esistant state thus may be egaded as the basis of a metabolic angiopathic syndome, "syndome X." 1 In the pesent investigation fo most of the factos investigated, fo example, blood pessue, lipopotein concentations, live enzyme activities, uate concentation, o glucose infusion ate duing the clamp test, thee was no clea distinction between the nonobese and obese subgoups, between the nomoinsulinemic and hypeinsulinemic subgoups, o between the nomoglycemic and hypeglycemic subgoups. The only exception was FFA concentation, which was significantly moe elevated in the hypeglycemic goup than in the othe two obese goups. In the diabetic state adipocytes ae insulin esistant, 6 and insufficient inhibition of lipolysis in the adipocytes may explain the highe concentation of FFAs. An elevated potal vein concentation of fatty acids is associated with an inceased insulin esistance in the live, which may explain the educed inhibition of the glycogenolysis that causes hypeglycemia. 331 ' 32 Othe vaiables wee linealy elated to measues of insulin esistance and ae not paticulaly associated with any of the goup chaacteistics. Diastolic blood pessue was invesely coelated with the glucose infusion ate (= -0.55,p=0.003) and with the fasting insulin concentation (=0.53, p=0.004), and as much as 52% of the inteindividual vaiation in diastolic blood pessue could be explained by insulin concentation, glucose infusion ate, and glucose toleance. Seveal mechanisms linking insulin esistance to blood pessue egulation have been demonstated. 33 In a pospective study the plasma insulin concentation was an independent isk facto fo development of hypetension in late-middleaged men duing a 10-yea peiod, 34 which is the fist

10 ollae et al LL Activity and Insulin Sensitivity 1201 Muscle LL-activity, mu/g Muscle LL-activity, mu/g 100 t Downloaded fom by on Decembe 13, 2018 = 0.53 p = Glucose infusion ate go'-i2o' FIGURE 3. Scatteplot showing the elation between muscle lipopotein lipase (LL) activity (mulg) and glucose infusion ate (adjusted fo pevailing insulin concentation; mglkgbody wt/min/mux 100). n, Goup 1; u,goup 2; 9,goup 3; and A, goup 4 (see Figue 2, left panel). population-based suppot implicating insulin as a facto contibuting to the development of hypetension. Inceased levels of ALAT and uate wee found in the goups with the most ponounced insulin esistance in the pesent study and may be egaded as new chaacteistics of the insulin-esistance syndome. The VLDL secetion ate is elated to the pevailing insulin concentation. 1 In the diabetic state the FFA concentation is the most impotant facto detemining the VLDL secetion ate. 1 Both insulin and FFA concentations ae elated to insulin esistance. The esults in the pesent study also show that the capacity fo emoval of ciculating TGs is, to a lage extent, elated to insulin esistance. The emoval capacity was tested in a diect way by use of the IVFFT, which has been validated to eflect the catabolism of endogenous TG-ich lipopoteins. 26 Only muscle but not adipose tissue LL activity contibuted to an explanation of the inteindividual vaiation in fat toleance (by 26%), and togethe with the glucose infusion ate duing the clamp test, 39% of the vaiation was explained. In the fasting state about half of the hydolysis duing the IVFTT takes place in skeletal muscle. 26 Ou data demonstating that muscle LL activity has a key ole in intavenous fat toleance ae theefoe in ageement with those findings. This suggestion is futhe suppoted by the demonstation that 35% of the inteindividual vaiation of seum TG concentation was explained by posthepain plasma LL, muscle LL, and hepatic lipase activity togethe. The vaiations in both posthepain plasma LL and muscle LL activities wee to a lage degee explained by glucose infusion ate duing the clamp test. Also, othe esults indicate that the egulation of muscle LL activity may be elated to insulin action. Fo instance, the decease in insulin concentations duing physical execise and the inceases duing diet expeiments wee associated with the evese changes Fasting p-insulin, mu/i FIGURE 4. Scatteplot showing the elation between muscle lipopotein lipase (LL) activity (mu/g) and fasting plasma (p-) insulin concentation (mull) in the study population. Symbols ae the same as in Figue 3. in muscle LL activity. 35 " 38 Use of a euglycemic hypeinsulinemic clamp test significantly deceased 39 muscle LL activity afte 4 hous of modeate hypeinsulinemia. This demonstates that insulin itself (o the inceased glucose uptake in muscle cells duing hypeinsulinemia) downegulates muscle LL activity. This may be intepeted that the egulation of muscle LL activity is not insulin esistant and theefoe, in such a state when hypeinsulinemia pevails, LL activity is downegulated. Adipose tissue LL activity was not significantly diffeent among the fou obese and the nomal-weight contol goups. Howeve, we did not measue cell size in adipose tissue. If that had been done, it may be assumed that the thee obese goups would have had lage adipose cell sizes and would have expessed highe LL activity pe 10 6 cells. This is suppoted by a finding fom a pevious study 40 in which thee wee significant coelations between hepain-eleasable acetone ethe powde LL activity expessed pe cell and diffeent indexes of obesity. This coelation did not pesist when acetone ethe powde LL activity S-ALAT, /ykat/l 1.2 T = p = Glucose infusion ate FIGURE 5. Scatteplot showing the elation between seum alanine aminotansfease (S-ALAT) activity (/dcat/l) and glucose infusion ate (adjusted fo pevailing insulin concentation; mg/kg body wt/min/muxloo). Symbols ae the same as in Figue 3.

11 1202 Ateioscleosis and Thombosis Vol 11, No 5 Septembe/Octobe 1991 Downloaded fom by on Decembe 13, 2018 was expessed pe gam. Howeve, it may be questioned that LL activity should be expessed pe 10 6 cells because we analyzed the hepain-eleasable (extacellula) pat. Thus, by analogy, muscle LL activity should have been expessed pe 10 6 muscle fibes because muscle fibe size is also elated to obesity. Howeve, we egad the significant coelations between TG concentation in seum and muscle LL activity expessed pe gam as an indication of the impotance of muscle LL and as an indication that this way of expessing the LL activity is physiologically elevant. Hepatic lipase activity is known to be egulated by sex steoids. Fo example, duing teatment with estogens, activity of this enzyme is deceased, but when estogen is combined with a gestagen with andogenic popeties, hepatic lipase activity is upegulated, being eflected pimaily in inceases and deceases, espectively, in HDL cholesteol concentations. 41 " 43 Howeve, an invese elation between the degee of physical fitness (Vo 2max ) and hepatic lipase activity has been epoted. 44 Moe physically fit men have lowe insulin concentations than do less fit ones These obsevations ae compatible with the pesent finding of a positive coelation between the aea unde the cuve of insulin concentations and hepatic lipase activity. It is thus possible that insulin (o insulinelated cellula functions) may also be involved in the egulation of hepatic lipase activity. It may be suggested that the inceases in hepatic lipase activity may have been patly due to oveexposue of the live to FFAs. This could induce hepatic insulin esistance, futhe diminish hepatic insulin extaction, and educe the hepatic catabolism of sex steoids. 47 In conclusion, this study has demonstated that muscle LL activity is coelated with the seum TG concentation in the fasting state and intavenous fat toleance, indicating a ole fo impaied hydolysis of ciculating TGs in the hypetiglyceidemia of obesity and diabetes. Futhemoe, muscle LL activity was elated to glucose infusion ate, suggesting that the hypeinsulinemia associated with insulin esistance may have a downegulating effect on muscle LL activity. The pesent esults demonstate that seveal isk factos fo coonay heat disease, such as seum TG and HDL cholesteol concentations and blood pessue, ae coelated with insulin esistance, suppoting the concept that insulin esistance is an impotant undelying pathogenic condition. Refeences 1. Reaven GM: Role of insulin esistance in human disease. Diabetes 1988;3: Modan M, Halkin H, Almog S, Lusky A, Eshkol A, Shefi M, Shitit A, Fuchs Z: Hypeinsulinemia: A link between hypetension, obesity and glucose intoleance. / Clin Invest 1985;75: Reaven GM, Genfield S: Diabetic hypetiglyceidaemia: Evidence fo thee clinical syndomes. Diabetes 1982;30(suppl 2): Taskinen MR, Beltz WF, Hape I, Fields RM, Schonfeld G, Gundy SM, Howad BV: Effects of NIDDM on vey-lowdensity lipopotein tiglyceide and lipopotein B metabolism: Studies befoe and afte sulfonyluea theapy. Diabetes 1986; 35: Robinson DS: The function of the plasma tiglyceides in fatty acid tanspot, in Flokin M, Stotz EH (eds): Compehensive Biochemisty. Amstedam, Elsevie Science ublishing Co, Inc, 1970, vol 18, pp Bolinde J, Lithell H, Skafos E, Ane : Effects of obesity, hypeinsulinemia, and glucose intoleance on insulin action in adipose tissue of sixty-yea-old men. Diabetes 1986;35: Lithell H, Lindgade F, Hellsing K, Lundqvist G, Nygaad E, Vessby B, Saltin B: Body weight, skeletal muscle mophology, and enzyme activities in elation to fasting seum insulin concentation and glucose toleance in 48-yea-old men. Diabetes 1981;30: Lithell H, Kotkiewski M, Kiens B, Woblewski Z, Holm G, Stdmblad G, Gimby G, Bjontop : Non-esponse of muscle capillay density and lipopotein-lipase activity to egula taining in diabetic patients. Diabetes Res 1985;2: Gimby G, Wilhelmsen L, Bjontop, Saltin B, Tibblin G: Habitual physical activity, aeobic powe and blood lipids, in enow B, Saltin B (eds): Muscle Metabolism Duing Execise. New Yok, lenum ublishing Cop, 1971, pp ollae T, Lithell H, Selinus I, Bene C: Application of pazosin is associated with an incease of insulin sensitivity in obese patients with hypetension. Diabetologia 1988;31: Ikkos D, Luft R: On the intavenous glucose toleance test. Ada Endocinol (Copenh) 1957;25: Jeppsson J-O, Jentop, Sundkvist G, Englund H, Nylund V: Measuement of hemoglobin A]C by a new liquid-chomatogaphy assay: Methodology, clinical utility, and elation to glucose toleance evaluated. Clin Chem 1986;32: DeFonzo RA, Tobin JD, Andes R: Glucose clamp technique: A method fo quantifying insulin secetion and esistance. Am Jhysiol 1979;237:E214-E Altszule N, Bakai A, Bjeknes C, Gottlieb B, Steele R: Glucose tunove values in the dog obtained with vaious species of labeled glucose. Am J hysiol 1975;229: Siegle L, Wu TW: Sepaation of seum high-density lipopotein fo cholesteol detemination: Ultacentifugation vs pecipitation with sodium phosphotungstate and magnesium chloide. Clin Chem 1981;27: Hisch J, Goldick RB: Seial studies on the metabolism of human adipose tissue: I. Lipogenesis and fee fatty acid uptake and elease in small aspiated samples of subcutaneous fat. / Clin Invest 1964;43: Begstom J: Muscle electolytes in man. Scand J Clin Lab Invest 1962;14(suppl):l Nilsson-Ehle, Schotz MC: A stable adioactive substate emulsion fo assay of lipopotein lipase. / Lipid Res 1976;17: Lithell H, Bobeg J: A method of detemining lipopoteinlipase activity in human adipose tissue. Scand J Clin Lab Invest 1977;37: Lithell H, Bobeg J: Detemination of lipopotein-lipase activity in human skeletal muscle tissue. Biochim Biophys Ada 1978;528: Ane, Engfeldt, Lithell H: Site diffeences in the basal metabolism of subcutaneous fat in obese women. / Clin Endocinol Metab 1981;53: Bobeg J, Calson LA: Detemination of hepain-induced lipopotein lipase activity in human plasma. Clin Chim Ada 1964;10: Nilsson-Ehle, Ekman R: Rapid, simple and specific assays fo lipopotein lipase and hepatic lipase. Atey 1977;3: Nilsson-Ehle, Gafinkel AS, Schotz MC: Lipolytic enzymes and plasma lipopotein metabolism. Annu Rev Biochem 1980; 49: Calson LA, Rossne S: A methodological study of an intavenous fat toleance test with Intalipid emulsion. Scand J Clin Lab Invest 1972;29:

12 Downloaded fom by on Decembe 13, Rossne S: Studies on an intavenous fat toleance test: Methodological, expeimental and clinical expeiences with Intalipid. Ada Med Scand 1974(suppl 564):l Steele R: Influences of glucose loading and of injected insulin on hepatic glucose output. Ann N YAcad Sci 1959;82: Cowan JS, Hetenyi G: Glucoegulatoy esponses in nomal and diabetic dogs ecoded by a new tace method. Metabolism 1971;20: Davidson MB, Hais MD, Rosenbeg CS: Invese elationship of metabolic cleaance ate of insulin to body mass index. Metabolism 1987;36: Feannini E, Haffne SM, Sten M: Essential hypetension: An insulin-esistant state. / Cadiovasc hamacol 1990; 15(suppl 5):S18-S Stomblad G, Bjontop : Reduced hepatic insulin cleaance in ats with dietay-induced obesity. Metabolism 1986;35: Bevilacqua S, Bonadonna R, Buzzigioli G, Boni C, Ciociao D, Maccai F, Gioico MA, Feannini E: Acute elevation of fee fatty acid levels leads to hepatic insulin esistance in obese subjects. Metabolism 1987;36: Feai, Weidmann : Insulin, insulin sensitivity and hypetension. / Hypetens 1990;8: Skafos ET, Lithell HO, Selinus I: Risk factos fo development of hypetension: A ten-yea longitudinal study in middleaged men. / Hypetens 1991;9: Lithell H, Bobeg J, Hellsing K, Lundqvist G, Vessby B: Lipopotein-lipase activity in human skeletal muscle and adipose tissue in the fasting and the fed states. Atheoscleosis 1978;30: Lithell H, Jacobs I, Vessby B, Hellsing K, Kalsson J: Decease of lipopotein lipase activity in skeletal muscle in man duing a shot tem cabohydate-ich dietay egime: With special efeence to HDL-cholesteol, apolipopotein and insulin concentations. Metabolism 1982;31: Lithell H, Kalstom B, Selinus I, Vessby B, Fellstom B: Is muscle lipopotein lipase inactivated by odinay amounts of dietay cabohydates? Hum Nut Clin Nut 1985;39C: ollae et al LL Activity and Insulin Sensitivity Taskinen MR, Nikkila EA, Rheumen S, Godin A: Effect of acute vigoous execise on lipopotein lipase activity of adipose tissue and skeletal muscle in physically active mm. Atey 1980;6: Kiens B, Lithell H, Mikines KJ, Richte EA: Effects of insulin and execise on muscle lipopotein lipase activity in man and its elation to insulin action. J Clin Invest 1989;84: ykalisto OJ, Smith H, Bunzell DJ: Deteminants of human adipose tissue lipopotein lipase: Effect of diabetes and obesity on basal- and diet-induced activity. / Clin Invest 1975;56: Tikkanen MJ, Kuusi T, Vatianen E, Nikkila EA: Teatment of postmenopausal hypecholesteolaemia with estadiol.y4c/a Obstet Gynecol Scand Suppl 1979;88: Tikkanen MJ, Nikkila EA, Kuusi T, Siponen S: High density lipopotein-2 and hepatic lipase: Recipocal changes poduced by estogen and nogestel. J Clin Endocinol Metab 1982;54: Tikkanen MJ, Nikkila EA, Kuusi T, Siponen S: Effects of oestadiol and levonogestel on lipopotein lipids and posthepain plasma lipase activities in nomolipopoteinaemic women. Acta Endocinol 1982;99: Stubbe I, Hansson, Gustafson A, Nilsson-Ehle : lasma lipopoteins and lipolytic enzyme activities duing enduance taining in sedentay men: Changes in high-density lipopotein subfactions and composition. Metabolism 1983;32: Rosenthal M, Haskell WL, Solomon R, Widstom A, Reaven GM: Demonstation of a elationship between level of physical taining and insulin-stimulated glucose utilization in nomal humans. Diabetes 1983;32: Heath GW, Gavin JR, Hindelite JM, Hagbeg JM, Bloomfield SA, Holloszy JO: Effects of execise and lack of execise on glucose toleance and insulin sensitivity. J Appl hysiol Envion Exec hysiol 1983;55: Haffne SM, Katz MS, Sten M, Dunn JF: The elationship of sex homones to hypeinsulinemia and hypeglycemia. Metabolism 1988;37: KEY WORDS lipopotein lipase activity insulin sensitivity insulin lipids obesity diabetes