receptor blockade prevents left ventricular remodeling and deterioration of cardiac function in experimental heart failure

Transcription

1 Crdiovsculr Reserch 39 (1998) Selective ET receptor blockde prevents left ventriculr remodeling nd deteriortion of crdic function in experimentl hert filure b c d Pul Mulder, Vincent Richrd, Frnçois Bouchrt, Genevieve Derumeux, Klus Munter, bstrct Christin Thuillez, * VCOMED, Deprtment of Phrmcology, (IFRMP no. 23),Rouen University Medicl School, Rouen, Frnce b VCOMED, Deprtment of Crdiology, Rouen University Medicl School, Rouen, Frnce c VCOMED, Deprtment of Crdic Surgery, Rouen University Medicl School, Rouen, Frnce d Knoll G, Ludwigshfen, Germny Received 19 Februry 1998; ccepted 26 My 1998 Bckground: Left ventriculr (LV) diltion, which is predictor of survivl in humns with chronic hert filure (CHF), is limited by mixed endothelin ET ntgonist. Whether selective ET receptor blockde influences LV diltion is unknown. We determined, in rt model of CHF, the effects of the ET receptor blocker LU on LV remodeling. Methods nd Results: Rts were subjected to coronry rtery ligtion nd treted for ten weeks with plcebo or LU (LU), t dose of 10 or 30 mg kg dy. Systolic blood pressure nd hert rte (plethysmogrphy) were determined in conscious nimls before nd fter four nd ten weeks of tretment. t these time points, crdic output nd LV dimensions were mesured in nesthetized rts by trnsthorcic echocrdiogrphy. LV hemodynmics were determined in nesthetized rts fter ten weeks. Pressor responses to ET-1 (1 nmol/ kg, i.v.) nd srfotoxin S6c (0.3 ng/ kg, i.v.) were mesured, to ssess the efficcy of ET receptor ntgonism nd the lck of blockde of ETB receptor blockde, respectively. The pressor response to ET-1 ws significntly reduced by LU (% chnge in systolic blood pressure: shm: 961; CHF: 561; CHF LU: 063 nd 2462% for the low nd high dose, respectively). LU did not ffect the response to srfotoxin (CHF: 23763; CHF LU: nd 22862% for the low nd high dose, respectively). Both doses of LU decresed systolic blood pressure, but only the high dose of LU reduced hert rte. Furthermore, LU restored crdic output dose-dependently throughout the study. Both doses of LU limited LV dilttion nd deteriortion of LV frctionl shortening to the sme extent. fter ten weeks, LU normlized LV end-distolicnd centrl venous pressures, but did not ffect LV dp/dtmx or dp/dt min. LU did not prevent the development of crdic hypertrophy, but reduced LV collgen density. Conclusions: In this rt model, the selective ET receptor blocker LU, t the dose of 30 mg kg dy, reduced blood pressure nd hert rte, limited progressive left ventriculr remodeling nd improved crdic hemodynmics nd function. These effects of LU might hve importnt clinicl relevnce in the tretment of hert filure Elsevier Science B.V. ll rights reserved. Keywords: Hert filure; ET blockde; Crdic remodeling; Rt; Echocrdiogrphy 1. Introduction sttus. Moreover, LV dilttion is inversely correlted with survivl in humns [4], nd prevention/ limittion of LV Congestive hert filure (CHF) is chrcterized, in remodeling is beneficil in CHF. Indeed, long-term therpy humns nd in experimentl niml models [1 3], by with ngiotensin converting enzyme (CE) inhibitor progressive left ventriculr (LV) diltion, which plys provokes, besides n improvement of systemic nd crdic key role in the deteriortion of the pthophysiologicl hemodynmics, limittion of crdic remodeling in humns with CHF [5 7] nd niml models [8,9] nd * these effects re ssocited with reduced mortlity rte. Corresponding uthor. Service de Phrmcologie, Hopitl ˆ de Bois Guillume, CHU de Rouen, Rouen Cedex, Frnce. Tel.: Incresed endothelin (ET) plsm concentrtions [ ; Fx: ; E-mil: christin.thuillez@churouen.fr Time for primry review 33 dys. ` / 98/ $ Elsevier Science B.V. ll rights reserved. PII: S (98)00159-X

2 P. Mulder et l. / Crdiovsculr Reserch 39 (1998) ] reflect nother min feture of CHF, i.e. neuro-humorl model of CHF, the effects of chronic tretment with the ctivtion, nd is lso mjor predictor of mortlity fter selective ET blocker LU on LV hemodynmics myocrdil infrction [15]. Using the rt myocrdil nd remodeling. infrction model, which predicted the beneficil effects of CE inhibitors [8,9], we recently demonstrted tht long term tretment with mixed ET ntgonist reduced 2. Methods blood pressure nd hert rte, limited crdic remodeling nd improved long term survivl [16]. Beneficil hemo- The investigtion conforms with the Guide for the Cre dynmic effects hve lso been reported in the sme model nd Use of Lbortory nimls published by the US fter cute dministrtion of mixed ET ntgonist Ntionl Institutes of Helth (NIH Publiction No , [17]. However, whether or not selective ET receptor revised 1996). ntgonists induce similr effects to those of mixed ET ETB receptor ntgonists is unknown. In theory, selective 2.1. nimls nd tretment ET receptor ntgonists would hve the dvntge of mintining ETB-medited, endothelium-dependent vso- Myocrdil infrction ws produced in ten-week-old dilttion, nd possibly of reducing the increse in plsm mle Wistr rts by left coronry rtery ligtion [8,16,24]. levels of ET. However, it is importnt to note tht ETB For this purpose, nimls were nesthetized with sodium receptors re lso present on smooth muscle cells nd methohexitl (50 mg kg, i.p.). The trche ws intubted induce vsoconstriction [18]. ETB receptors my lso nd the nimls were mechniclly ventilted with ir from medite hypertrophic signls nd be involved in the ET- the room. fter left thorcotomy, the proximl left induced synthesis of collgen by crdic fibroblsts [19]. coronry rtery ws occluded by suture in order to Moreover, it hs been suggested tht ETB vsoconstriction induce myocrdil infrction. Shm-operted rts were my become cliniclly relevnt only under subjected to the sme protocol, except tht the snre ws pthophysiologicl conditions, through n enhnced not tied. Fifteen min fter occlusion, the chest ws closed smooth musculr ETB receptor expression/ sensitivity nd/ nd the nimls were llowed to recover from nesthesi. or reduced ET -medited relese of endothelium-derived The 24-h mortlity rte ws bout 20% for the infrction B vsodilting fctor(s) [20]. Thus, bsed on these opposite group. Fifteen shm-operted rts were used s controls. theoreticl rguments, it is not possible to predict whether Rts were rndomly ssigned to three groups (n520 selective ET ntgonists will show better or similr ech), i.e. untreted, or treted with LU t dose of either efficcy compred to mixed ET ET ntgonists. 10 mg kg dy or 30 mg kg dy. These doses B In rbbits with pcing-induced CHF, three-week were chosen on the bsis of preliminry short term tretment with the non-peptide selective ET blocker, PD experiments which showed tht they were ssocited with [], hs been shown to improve LV function, in significnt decreses in blood pressure, nd tht dministhe bsence of n effect on systemic blood pressure. trtion of doses higher thn 30 mg/ kg ws ssocited with However, whether or not similr functionl chnges occur decresed response to the ETB gonist srfotoxin S6C, fter longer periods of tretment is unknown. Moreover, suggesting blockde of ET receptors (K Munter, personl whether or not specific ET ntgonists lso ffect LV communiction). function in models of ischemi-induced hert filure is Tretment with LU ws strted seven dys fter ligtion, unknown. In ddition, lthough Ski et l. [22] reported in greement with previous studies [8,9,16], in order to tht the selective peptide ET ntgonist, BQ-123, limited void interference with the heling process nd/ or the LV remodeling, this evidence ws bsed only on qulittive erly distention of the infrct zone. histologic estimtion, nd no estimte of LV function ws ll tretments, provided by Knoll G (Ludwigshfen, performed. Thus, to our knowledge, no dt re vilble Germny), were given s food dditive for ten weeks. Rts on the long term effects of selective ET blockde on were weighed every week nd their food intke ws crdic function nd structure. mesured in order to llow djustment of the drug con- LU (LU) is non-peptide ET receptor centrtions in chow. ntgonist, hving 130-fold higher ffinity for the humn ET receptor thn for the ETB receptor. In rts with CHF, 2.2. Hemodynmic mesurements LU dose-dependently reduces systolic blood pressure nd hert rte [23]. Furthermore, in this model, LU reduces LV Systolic blood pressure (plethysmogrphy) nd hert end-distolic pressure, without hving ny inotropic ef- rte were determined in conscious rts before the strt of fects. However, whether or not these beneficil hemo- the tretment (i.e. one week fter the surgicl procedure; dynmic effects re ssocited with limittion of the W 0) nd fter four (W 4) nd ten weeks (W 10) of tretment. progressive deteriortion of LV remodeling in CHF is t the end of the study, the surviving rts were unknown. nesthetized with pentobrbitl (50 mg kg, i.p.). The Thus, the gol of our study ws to determine, in rt right crotid rtery nd the right externl jugulr vein were B

3 602 P. Mulder et l. / Crdiovsculr Reserch 39 (1998) cnnulted with micromnometer-tipped ctheter (SPR of Echocrdiology leding-edge method from t lest three 407, Millr Instruments, US) nd dvnced into the ort consecutive crdic cycles [26]. Mesurements were pernd thorcic ven cv, respectively, for the recording of formed by single observer (P.M.) who ws blinded to rteril nd centrl venous pressures. The ortic ctheter prior results nd tretment groups. ws then dvnced into the left ventricle (LV) for the Exmples of M-mode recordings, obtined t the end of recording of LV pressure nd its mximl rte of rise the ten week protocol, in shm nd untreted myocrdil (dp/dt mx) nd decrese (dp/dt min). ll trcings were infrcted rts re shown in Fig. 1. The dimeter of the LV recorded on physiologic recorder (Windowgrph, cvity nd the thickness of the nterior nd posterior wlls Gould). were determined t the level of the ppillry muscle [25]. LV posterior wll thickening ws clculted s (posterior 2.3. Echocrdiogrphic studies end-distolic wll thickness2posterior end2systolic wll thickness)/ posterior end-distolic wll thickness, nd ws Trnsthorcic Doppler echocrdiogrphic studies were expressed s percentge. Frctionl shortening ws performed in rts just before the strt of the tretment (i.e. clculted s (LV end-distolic cvity dimeter2lv endseven dys fter the surgicl procedure) nd fter four nd systolic cvity dimeter)/ LV end-distolic cvity dimeter, ten weeks of tretment. For this purpose, rts were nd ws expressed s percentge. In ddition, LV outflow nesthetized with methohexitl (50 mg kg, i.p.), the velocity ws mesured by pulsed-wve Doppler, nd chest ws shved nd echocrdiogrms were performed crdic output ws clculted s CO5ortic VTI3[P(LV with n echocrdiogrphic system equipped with 7-MHz 2 outflow dimeter/ 2) ]3hert rte, where VTI is the vetrnsducer (cuson 128 XP/ 10C), s described previously locity time integrl. [16,25]. Briefly, two-dimensionl short xis view of the left ventricle ws obtined t the level of the ppillry 2.4. Efficcy of ET receptor ntgonism nd selectivity muscle, in order to record M-mode trcings. nterior nd of ET receptor blockde posterior end-distolic nd end-systolic wll thickness nd LV dimeters were mesured using the mericn Society In order to ssess the efficcy of ET receptor ntgonism Fig. 1. Exmples of M-mode recordings in shm-operted rt nd n untreted rt with myocrdil infrction, t the end of the ten week protocol. In these typicl exmples, there is symmetric thickening of the nterior nd posterior wlls in the shm-operted rt. In contrst, the nterior wll is thinned nd kinetic, while the posterior wll is hypokinetic, in the untreted myocrdil infrcted rt. Moreover, the left ventricle cvity is significntly dilted.

4 P. Mulder et l. / Crdiovsculr Reserch 39 (1998) nd the selectivity of ET receptor blockde, vritions in treted CHF control group (3362%). During the tretment systolic blood pressure, induced by n intrvenous bolus period, four untreted CHF rts, four CHF rts treted with injection of ET1 (1 nmol kg ) nd srfotoxin S6c (0.3 LU t 10 mg kg dy nd three CHF rts treted with ng kg ), were determined. LU t 30 mg kg dy died Crdic morphometry 3.2. Systemic hemodynmic mesurements in conscious rts Morphometric nlyses were performed s described previously [27,28]. The tri, left nd right ventricles were One week fter coronry rtery ligtion, systolic blood weighed seprtely, nd the left ventricle ws immersed in pressure in untreted CHF rts ws significntly lower thn Bouin s fixtive solution. fter fixtion, the hert ws cut tht of shm-operted rts, wheres hert rte ws sigperpendiculr to the pex to bse xis into three sections of nificntly ugmented (Fig. 2). t this time (i.e. immedipproximtely identicl thickness. Sections were dehy- tely before the onset of tretment), both systolic blood drted nd embedded in prffin. From these sections, 3 pressure nd hert rte in the low nd high dose LU treted mm thick histologic slices were obtined nd were stined groups were not different from those of the untreted CHF with Sirius Red. rts. Compred to untreted CHF rts, both the low nd For the mesurement of infrct size, slices were plced high dose of the ET ntgonist LU induced decrese in under video microscope (Microwtcher VS-30H, Mit- systolic blood pressure fter four weeks (W 4: 3 nd subishi Ksei Coopertion) with 20-fold enlrgement 8 mmhg, both p,0.05 vs. time-mtched untreted lens. The endocrdil nd epicrdil circumferences of the CHF). While this effect remined significnt throughout infrcted tissue nd of the left ventricle were determined the study for the high dose of LU (2 mmhg t W 10, using imge nlysis softwre (CYBERVIEW, Cervus Intern- p,0.05 vs. time-mtched untreted CHF rts), it did not tionl). Infrct size ws clculted s (endocrdil1 rech sttisticl significnce for the low dose (26 mmhg epicrdil circumference of the infrcted tissue)/(endo- t W 10). Simultneously, only LU t the dose of 30 mg crdil1epicrdil circumference of the left ventricle) nd kg dy, reduced hert rte throughout the study (226 the result ws expressed s percentge. nd 4 bets min t W4 nd W 10, p,0.05 vs. time- For the determintion of crdic collgen density, mtched untreted CHF rts). imges (500-fold enlrgement) were obtined in the noninfrcted subepicrdil region of the left ventricle on Sirius 3.3. Echogrphic mesurements in nesthetized rts Red-stined slides. The volume of the collgen frction ws clculted s the sum of the surfce of ll connective One week fter surgery, LV end-distolic nd endtissue res divided by the totl surfce of the imge. systolic dimeters were significntly incresed in infrcted Perivsculr collgen ws excluded from this mesure- nimls (Fig. 3). While both left ventriculr end-distolic ment. It hs been shown tht the totl volume frction, s nd end-systolic dimeters remined stble throughout the determined by this morphometric pproch, is closely study in shm nimls, they significntly incresed over relted to the hydroxyproline concentrtion of the ventricle [29,30] Sttisticl nlysis ll results re given s the men6sem. Intergroup differences were evluted by NOV nd were followed by Tukey test for multiple comprisons, using BMDP softwre, if NOV reveled significnt differences. Differences were considered to be significnt t the level of p, Results 3.1. Infrct size nd mortlity Fig. 2. Systolic blood pressure (left) nd hert rte (right) mesured in Infrct sizes in the surviving nimls tht were scrificed conscious shm-operted rts (open circles) or rts with CHF, either untreted (solid circles) or treted using LU t doses of 10 mg kg dy fter ten weeks were identicl in the groups treted with (solid tringles) or 30 mg kg dy (open tringles). n per LU t both low nd high doses (3063 nd 3362%, group. * p,0.05 vs. untreted CHF; p,0.05 vs. CHF rts treted with respectively) nd were comprble to those of the un- LU t 10 mg kg dy.

5 604 P. Mulder et l. / Crdiovsculr Reserch 39 (1998) Fig. 3. LV end-distolic (left) nd LV systolic (right) inner cvity Fig. 5. Crdic output (left) nd stroke volume (right) mesured in dimeters, mesured in nesthetized shm-operted rts (open circles) or nesthetized shm-operted rts (open circles) or rts with CHF, either rts with CHF, either untreted (solid circles) or treted with LU t dose untreted (solid circles) or treted using LU t doses of 10 mg kg dy of 10 mg kg dy (solid tringles) or 30 mg kg dy (open (solid tringles) or 30 mg kg dy (open tringles). n per tringles). n per group. * p,0.05 vs. untreted CHF. group. * p,0.05 vs. untreted CHF; p,0.05 vs. LU t 10 mg kg dy. time in untreted infrcted nimls. Immeditely before the onset of tretment, left ventriculr dimensions in the low One week fter surgery, crdic output ws significntly nd high dose LU groups were similr nd were not diminished in infrcted nimls compred to shm-operdifferent from those of the untreted CHF rts. Both the ted rts nd remined lower throughout the study (Fig. 5). low nd high doses of LU limited, but did not completely Immeditely before the strt of tretments, crdic output prevent, the subsequent increse in LV end-distolic nd in the low nd high dose LU groups were not different end-systolic dimeters. from tht of the untreted CHF rts. Throughout the One week fter surgery, LV frctionl shortening ws tretment period, crdic output ws incresed by both the significntly diminished in infrcted nimls compred to low nd high doses of LU, however, this effect ws more shm-operted rts nd continued to decrese fterwrds, mrked with the high dose. Finlly, one week fter reching plteu fter four weeks (Fig. 4). LU t the surgery, stroke volume ws significntly decresed in doses of 10 nd 30 mg kg dy prevented the decrese infrcted nimls compred to shm-operted rts. Comin LV frctionl shortening. Furthermore, seven dys fter pred to untreted CHF nimls, LU improved stroke surgery, ligtion induced depression of LV posterior wll volume, nd even normlized it in the group treted with thickening nd this slightly worsened over time. LU the high dose. prevented this worsening, however, compred to timemtched CHF control rts, this effect reched sttisticl 3.4. Crdic hemodynmic mesurements in nesthetized significnce only for the high dose. rts fter ten weeks nd s compred to shm-operted nimls, CHF decresed LV systolic pressure, LV dp/dt mx nd LV dp/dt min, nd cused significnt increse in LV end-distolic pressure (LVEDP) nd centrl venous pressure (Tble 1). Compred to untreted CHF rts, both the low nd the high dose of LU reduced LV systolic pressure, nd normlized both LVEDP nd centrl venous pressure, without ffecting LV dp/dtmx or LV dp/dt min Efficcy of ET receptor ntgonism nd selectivity of ET receptor blockde The ETB gonist srfotoxin S6c induced trnsient decrese in systolic blood pressure in ll groups (shm: Fig. 4. LV frctionl shortening (left) nd LV posterior wll thickening 23164; CHF control: 23763; CHF LU: nd (right) mesured in nesthetized shm-operted rts (open circles) or rts with CHF, either untreted (solid circles) or treted using LU t doses of 22862% for doses of 10 nd 30 mg kg dy, 10 mg kg dy (solid tringles) or 30 mg kg dy (open tringles). respectively). The vritions mong the different groups n per group. * p,0.05 vs. untreted CHF rts. did not rech sttisticl significnce.

6 P. Mulder et l. / Crdiovsculr Reserch 39 (1998) Tble 1 Crdic hemodynmics fter ten weeks of tretment Chronic hert filure Shm Control LU 10 mg/kg/dy LU 30 mg/kg/dy LVSP LVEDP (mmhg) CVP (mmhg) LV dp/dt mx (10 mmhg s ) LV dp/dt (10 mmhg s ) min bc b b b b 3 3 LVSP, left ventriculr systolic pressure (mmhg); LVEDP, left ventriculr end distolic pressure (mmhg); CVP, centrl venous pressure (mmhg). b c vs. shm; p,0.05 vs. CHF control; p,0.05 vs. CHF LU t 10 mg kg dy. The non-selective ET gonist ET-1 induced n increse throughout the study. However, it should be stressed tht in systolic blood pressure in the shm nd CHF control 75% of this dilttion fter the heling phse occurred group (961 nd 561%, respectively, NS). Compred to during the first four weeks, fter which, the progression of the CHF control vlue, LU, t doses of 10 nd 30 mg kg LV dilttion slowed down. dy, reduced the increse in systolic blood pressure LV diltion ws ccompnied by progressive depresinduced by ET-1 (062 nd 2462%, respectively), but this sion of LV frctionl shortening nd LV posterior wll effect reched sttisticl significnce ( p,0.05) only for function, indicting n impired LV systolic function. s the dose of 30 mg kg dy. lredy reported [16,25], LV frctionl shortening nd LV posterior wll thickening worsened further over time, 3.6. Crdic morphology suggesting further deteriortion of LV function. Crdic output nd stroke volume were significntly Hert weight, LV nd right ventriculr (RV) weights s reduced throughout the study in untreted CHF rts. Thus, well s LV collgen density were significntly incresed in LV diltion ws unble to mintin stroke volume, leding, untreted CHF rts. LU never ffected hert weight, LV despite the increse in hert rte, to reduced crdic nd RV weights, but it significntly reduced LV collgen output. density (Tble 2). LU dose-dependently reduced rteril blood pressure nd hert rte. Similr systemic hemodynmic results hve been reported with mixed ET receptor blockers in 4. Discussion humns [31] s well s in experimentl niml models [16,17]. This is in greement with the results of Ski et l. In this study, the effects of the ET receptor ntgonist [22] who used the peptide ET ntgonist, BQ-123, in the LU on systemic nd crdic hemodynmics in rt model, but does not concord with those obtined in rt model of CHF, s well s its impct on the progression model of pcing-induced hert filure with the selective of post-infrction left ventriculr remodeling, using seril ET ntgonist PD [], which reduced hert rte echogrphic mesurements, were investigted. without ny modifiction of rteril blood pressure. How- Coronry rtery ligtion in the rt hs provided exten- ever, this could be due to differences on the model of CHF sive informtion bout the progression from LV dysfunc- used in the two studies (i.e. coronry rtery ligtion in the tion to the pthophysiologicl stte of overt hert filure. present study vs. pcing in the previous study), or to Seven dys fter coronry rtery ligtion, in ddition to the differences in the phrmcologicl profiles of these two clssicl hemodynmic signs of CHF, i.e. decrese in ntgonists or to the doses dministered. systolic blood pressure nd n increse in hert rte, LV Our experimentl design does not llow us to determine end-distolic- nd end-systolic dimeters were significntly whether the reduction of hert rte is the consequence of incresed [3,16,25], nd the LV continued to dilte blockde of the positive chronotropic properties of ET [32] p,0.05 Tble 2 Crdic weight nd collgen density fter ten weeks of tretment Chronic hert filure Shm Control LU (10 mg kg dy ) LU 30 (mg kg dy ) Hert weight (g) LV weight (g) RV weight (g) LV collgen (%) LV, left ventricle; RV, right ventricle. p,0.05 vs. CHF control.

7 606 P. Mulder et l. / Crdiovsculr Reserch 39 (1998) or it is relted to reduced sympthetic tone, secondry to nd the doses used might lso not be comprble in terms the improved hemodynmic conditions. However, whttwo of the level of blockde of the receptors. Moreover, the ever the mechnism, the reduction in hert rte might hve drugs hve been evluted in two different studies, importnt consequences. Indeed, due to the non-linerity of with two different observtion periods (ten vs. eight the hert rte distolic prt of the crdic cycle, smll weeks). definitive proof for different effects of these two decrese in hert rte results in drmtic increse in the types of ntgonists would probbly require more rigorous distolic coronry perfusion time [33 35] nd improves comprisons with full dose response curves, or compri- LV filling [36]. This, together with reduced oxygen re- son of the chronic effects of n ET ntgonist with those quirements induced by the decrese in hert rte [37,38], of simultneous dministrtion of the ET ntgonist will improve the oxygen supply demnd rtio, nd this together with selective ETB ntgonist. To the best of our might be beneficil, in terms of crdic reserve. knowledge, this kind of experiment hs not been per- The decrese in blood pressure might lso contribute, formed. through decresed oxygen demnd, to the beneficil effect Frctionl shortening nd posterior wll thickening were of the ET ntgonist in CHF. However, sustined significntly improved by LU. This, together with the drmtic decrese in blood pressure might be deleterious in hemodynmic effects, s well s the decrese in hert rte CHF, through the impired regionl tissue perfusion it nd LV dilttion, my induce n improvement of LV induces. However, this is rther unlikely in the present filling nd n increse in crdic output without decresing experiments, since the hypotensive effect of the ET crdic contrctility. This is confirmed in our study, in ntgonist remins limited. Is should lso be stressed tht which LU incresed crdic output s well s stroke this hypotensive effect is less mrked thn tht induced in volume nd prevented the deteriortion of globl LV the sme model by CE inhibitors, which re clerly function, without ffecting LV dp/dt. beneficil in this setting. LU did not ffect crdic hypertrophy. This finding is s described for the selective ET receptor ntgonist not limited to selective ET receptor blockde, since PD [] or the ET ntgonist bosentn bosentn similrly does not prevent crdic hypertrophy [16,17], LU reduced crdic prelod, s illustrted by the [16]. The lck of ET blockde on crdic hypertrophy reduction of LV end-distolic pressure s well s centrl could be surprising, since ET hs been shown to induce venous pressure, which ws determined in nesthetized myocyte hypertrophy in vitro [41] nd to be implicted in nimls t the end of the tretment period, without cusing ngiotensin II-induced myocyte hypertrophy [42]. More- chnges in LV contrctility. lthough cute dministrtion over, LU induced mjor chnges in crdic prelod nd of the ET ntgonist BQ-123 hs been shown to decrese decresed blood pressure, which hve been shown to be LV contrctility in rts with CHF [39], possibly through implicted in crdic hypertrophy. Thus, the lck of effect prevention of the positive inotropic properties of ET [40], of ET ntgonists on crdic hypertrophy suggests tht our results suggest tht either endogenous ET in vivo does blockde of ET receptors t the level of the crdic tissue, not exert positive inotropic effect nd/ or tht the improvenisms t the doses used, is incomplete nd/or tht other mechment in the neuro-humorl nd hemodynmic sttus by ET re involved in the development of crdic hy- ntgonists overrules the possible direct negtive inotropic pertrophy, such s locl neuro-humorl ctivtion, overrul- effects due to ET receptor blockde. ing the effects of ET receptor blockde. In this hemodynmic context, LU limited the increse in Concerning the selectivity the ET blockde, LU 135 left ventriculr cvity enlrgement. Indeed, s described 252, t dose of 10 nd 30 mg kg dy, significntly with the ET ntgonist PD , left ventriculr end- reduced the pressor response to ET-1, without ffecting the distolic, nd systolic dimeters, obtined t the level of response to srfotoxin S6c. Thus, our results suggest tht, the ppillry muscle, were smller thn those observed in fter ten weeks of tretment, blockde of ET receptors by time-mtched hert filure nimls. It must be noted tht, LU is probbly limited to ET receptors. in our previous study, the mixed ET ntgonist Recently, the existence of ETB receptors on vsculr bosentn did not significntly ffect LV dimeters, l- smooth cells nd their vsoconstrictor properties upon though there ws tendency towrds decrese, despite stimultion hve been demonstrted [43]. However, their the fct tht this drug ws mrkedly effective on LV physiologicl role remins controversil. Under norml dilttion when ssessed s pssive pressure/ volume rel- conditions, the relese of vsodiltor substnces by stimutionship. lthough this might represent true difference ltion of endothelil ETB receptors my offset the vs- between specific nd mixed ntgonists, this difference oconstrictor properties of vsculr ETB receptors. Howmust be interpreted with cution. In prticulr, we do not ever, in CHF, which is ccompnied by reduced endobelieve tht it is sfe to ssume tht differences obtined thelil NO pthwy [27], the locl vsoconstrictor response between the effects of LU nd those of bosentn do to srfotoxin S6c is enhnced t the level of the brchil represent definitive proof for differences between ET rtery [43]. The fct tht, in our study, ETB receptor nd mixed ET ntgonists. Indeed, LU nd bosen- ctivtion only induced trnsient vsodilttion without tn might differ mrkedly in terms of phrmcokinetics, sustined vsoconstriction does not exclude locl,

8 P. Mulder et l. / Crdiovsculr Reserch 39 (1998) heterogeneous vsoconstriction, since we did not deter- with left ventriculr dysfunction fter myocrdil infrction. N Engl J Med. 1995;333: mine the effect of srfotoxin S6c t the level of different [7] Gudron P, Kugler I, Hu K, Eilles C, Ertl G. Quinpril, initited vsculr territories. fter dvnced ventriculr diltion in ptients with chronic infrc- In the present study, we found tht LU incresed the tion, prevents progressive remodeling (bstrct). J m Coll Crdiol ejection frction, in contrst with our previous study with 1996;27:228. bosentn, which did not ffect the ejection frction [16]. [8] Pfeffer M, Pfeffer JM, Steinberg C, Finn P. Survivl fter n experimentl myocrdil infrction: beneficil effects of long-term However, s mentioned before, this must be interpreted therpy with cptopril. Circ Res 1985;72: with cution nd does not represent definitive proof tht [9] Pfeffer JM, Pfeffer M, Brunwld E. Influence of chronic cptopril specific ET ntgonists differ from mixed ET therpy on the infrcted left ventricle of the rt. Circ Res ntgonists in terms of crdic function in hert filure. 1985;57: [10] Cvero PG, Miller WL, Heublein DM, Mrgulies KB, Burnett Jr. In the present study, we hve not ssessed the effect of JC. Endothelin in experimentl congestive hert filure in the tretment with LU in the presence of conven- nesthetized dog. m J Physiol 1990;259:F312 F317. tionl tretment for hert filure nd, especilly, in the [11] Mrgulies KB, Hildebrnd Jr. FL, Lermn, Perrell M, Burnett presence of CE inhibitors. Clerly, given the numbers of Jr. JC. Incresed endothelin in experimentl hert filure. Circul- tion 1990;82: known interctions between the renin ngiotensin nd the [12] Cody RJ, Hs GJ, Binkley PF, Cpers Q, Kelley R. Plsm endothelin systems, it would be importnt to ssess endothelin correltes with the extent of pulmonry hypertension in whether the effects of ET ntgonists do persist or re ptients with chronic congestive hert filure. Circultion potentited in the presence of chronic tretment with CE 1992;85: inhibitors or T receptor ntgonists. Clerly, this hy- [13] Cody RJ. The potentil role of endothelin s vsoconstrictor 1 substnce in congestive hert filure. Eur Hert J 1992;13:1573 pothesis requires further investigtion In conclusion, LU , t doses of 10 nd 30 mg [14] Wei CM, Lermn, Rodeheffer RJ. Endothelin in humn conges- kg dy, dministered chroniclly for ten weeks in rts tive hert filure. Circultion 1994;89: with chronic hert filure, dose-dependently decresed [15] Omlnd T, Lie RT, kvg, rslnd T, Dickstein K. Plsm endothelin determintion s prognostic indictor of 1-yer mortlirteril blood pressure nd hert rte nd improved crdic ty fter cute myocrdil infrction. Circultion 1994;89:1573 hemodynmics. Simultneously, LU limited the progression of left ventriculr remodeling nd the deterio- [16] Mulder P, Richrd V, Derumeux G. Role of endogenous endothelin rtion of left ventriculr function. This phrmcologicl in chronic hert filure: effect of long term tretment with n profile gives new perspectives in the tretment of hert endothelin ntgonist on survivl, hemodynmics nd crdic re- modeling. Circultion 1997;96: filure. [17] Teerlink JR, Loffler BM, Hess P. Role of endothelin in the mintennce of blood pressure in conscious rts with chronic hert filure. cute effects of the endothelin receptor ntgonist. Circultion cknowledgements 1994;90: [18] Clozel M, Gry G, Breu V, Loffler BM. The endothelin ET B receptor medites both vsodilttion nd vsoconstriction in vivo. The uthors thnk Mrie-Helene ` Mulot, Jen Pul Biochem Biophys Res Commun 1992;186: Henry, Frnçoise Lllemnd, Eline bdelhoub nd [19] Gurd E, Ktw LC, Myers PR, Tygi SC, Weber KT. Effects of Houssine Boujedıni for excellent ssistnce. endothelin on collgen turnover in crdic fibroblsts. Crdiovsc Res 1993;27: [20] Rsmussen TE, Jougski M, Supporn T, et l. Crdiovsculr ctions of ET-B ctivtion in vivo nd modultion by receptor References ntgonism. m J Physiol 1998;274:R131 R138. [] Spinle FG, Wlker JD, Mukherjee R, et l. Concomitnt endothelin [1] Gudron P, Eilles C, Kugler I, Ertl G. Progressive left ventriculr receptor subtype- blockde during the progression of pcingdysfunction nd remodeling fter myocrdil infrction. Potentil induced congestive hert filure in rbbits. Beneficil effects on left mechnisms nd erly predictors. Circultion 1993;87: ventriculr nd myocyte function. Circultion 1997;95: [2] Gudron P, Blumrich M, Ertl G. ggrvtion of left ventriculr [22] Ski S, Miyuchi T, Kobyshi M, et l. Inhibition of myocrdil dilttion nd reduction of survivl by clcium chnnel blocker in endothelin pthwy improves long term survivl in hert filure. rts with chronic myocrdil infrction. m Hert J 1993;125:1226 Nture 1996;384: [23] Pfeffer JM, Finn PV, Pfeffer M. Endothelin- receptor ntgonism [3] Pfeffer M, Brunwld E. Ventriculr remodeling fter myocrdil in rts with myocrdil infrction nd filure (bstrct). J m Coll infrction: experimentl observtions nd clinicl implictions. Crdiol 1997;29 (suppl ):399. Circultion 1990;91: [24] Selye H, Bjusz E, Grsso S, Mendell P. Simple techniques for [4] White HD, Norris RM, Brown M. Left ventriculr end-systolic surgicl occlusion of coronry vessels in the rt. ngiology volume s mjor determinnt of survivl fter recovery from 1960;11: myocrdil infrction. Circultion 1987;76: [25] Litwin SE, Ktz SE, Morgn JP, Dougls PS. Seril echocrdiog- [5] SVE. Effect of cptopril on mortlity nd morbidity in ptients rphic ssessment of left ventriculr geometry nd function fter with left ventriculr dysfunction fter myocrdil infrction. Results lrge myocrdil infrction in the rt. Circultion 1994;89: of the survivl nd ventriculr enlrgement tril. N Engl J Med [26] Shn DJ, DeMri, Kisslo J, Weymn. Recommendtions 1992;327: regrding quntittion in M-mode echocrdiogrphy: results of [6] Trndolpril Crdic Evlution (TRCE) Study. clinicl tril of survey of echocrdiogrphic mesurements. Circultion the ngiotensin-converting enzyme inhibitor trndolpril in ptients 1978;58:

9 608 P. Mulder et l. / Crdiovsculr Reserch 39 (1998) [27] Mulder P, Elfertk L, Richrd V, et l. Peripherl rtery structure nd hemodynmic drenergic bet-blockde nd long-term effects in endothelil function in hert filure. Effect of CE inhibition. m J ptients with hert filure. study on distolic function, hert rte Physiol 1996;271:H469 H477. nd myocrdil metbolism following intrvenous metoprolol. Eur [28] Mulder P, Devux B, Richrd V, et l. Erly vs delyed ngiotensin Hert J 1993;14: converting enzyme inhibition in experimentl chronic hert filure: [37] Kjekshus J. Hert rte reduction mechnism of benefit? Eur effects on survivl, hemodynmics nd crdiovsculr remodeling. Hert J 1987;8(suppl): Circultion 1997;95: [38] Frishmn WH, Gbor R, Pepine C, Cvusoglu E. Hert rte [29] Weber KT, Jnicki JS, Schroff SG, et l. Collgen remodeling of the reduction in the tretment of chronic stble ngin pectoris: expressure-overloded, hypertrophied nonhumn primte myocrdium. perience with sinus node inhibitor. m Hert J 1996;131: Circ Res 1988;62: [39] Ski S, Miyuchi T, Skuri T, et l. Endogenous endothelin-1 [30] Nicoletti, Heudes D, Hinglis N, et l. Left ventriculr fibrosis in prticiptes in the mintennce of crdic function in rts with renovsculr hypertensive rts. Effect of losrtn nd spironolc- congestive hert filure. Mrked increse in endothelin-1 production tone. Hypertension 1995;26: in the filing hert. Circultion 1996;93: [31] Kiowski W, Sutsch G, Hunziker P, et l. Evidence for endothelin-1- [40] Kelly R, Eid H, Krmer BK, et l. Endothelin enhnces the medited vsoconstriction in severe chronic hert filure. Lncet contrctile responsiveness of dult rt ventriculr myocytes to 1995;346: clcium by pertussis-toxin sensitive pthwy. J Clin Invest [32] Ishikw T, Yngisw M, Kimur S, Goto K, Mski T. Positive 1990;86: chronotropic effects of endothelin, novel endothelium-derived [41] Shubeit HE, McDonough PM, Hrris N, et l. Endothelin vsoconstrictor peptide. Pflug rch Eur J Physiol 1988;413:108 induction of inositol phospholipid hydrolysis, srcomere ssembly, 110. nd crdic gene expression in ventriculr myocytes: prcrine [33] Boudouls H, Rittgers SE, Lewis RP, Leier VC, Weissler M. mechnism for myocrdil cell hypertrophy. J Biol Chem Chnges in distolic time with vrious phrmcologicl gents: 1990;265: implictions for myocrdil perfusion. Circultion 1979;60:164 [42] Ito H, Hirt Y, dchi S, et l. Endothelin-1 is n utocrine/ 169. prcrine fctor in the mechnism of ngiotensin II-induced hy- [34] Litwin SE, Grossmn W. Distolic dysfunction s cuse of hert pertrophy in cultured rt crdiomyocytes. J Clin Invest filure. J m Coll Crdiol 1993;22: ;92: [35] Guth BD, Heusch G, Seitelberger R, Ross Jr. J. Mechnism of [43] Love MP, Hynes WG, Webb DJ, McMurry JJV. Vsodiltor effects beneficil effect of b-drenergic blockde on exercise-induced of endothelin-converting enzyme inhibition nd endothelin T myocrdil ischemi in conscious dogs. Circ Res 1987;60: receptor blockde in chronic hert filure ptients treted with CE [36] ndersson B, Lomsky M, Wgstein F. The link between cute inhibitors. Circultion 1996;94:31 37.