Angiotensin-converting enzyme inhibitors potentiate subthreshold preconditioning through NO and mitok ATP. channel

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1 Acta Physiologica Sinica, August 25, 2005, 57 (4): ATP ,* Langendorff ( ) ( ) (angiotensin-converting enzyme inhibitors, ACEI) (nitric oxide, NO) ATP (mitochondrial ATP-sensitive potassium channel, mitok ATP channel) ACEI (1) 2 min 10 min (subthreshold preconditioning, spc) ( 30 min min) (2) ACEI spc spc (left ventricular end-diastolic pressure, LVEDP) (left ventricular developed pressure, LVDP) (lactate dehydrogenase, LDH) spc (3) NOS L-NAME mitok ATP 5-HD 10 min / spc LVEDP LVDP LDH (P<0.05) (4) spc NO ACEI spc NO (P<0.05) ACEI NO mitok ATP ATP Q463 Angiotensin-converting enzyme inhibitors potentiate subthreshold preconditioning through NO and mitok ATP channel ZHANG Hong 1, ZHANG Bei 1, TANG Bo-Yu 1, CHEN Ying-Ying 2, ZHU Li 2, SHEN Yue-Liang 2,* 1 Department of Physiology, Huzhou Teachers College, Huzhou , China; 2 Department of Physiology, School of Medicine, Zhejiang University, Hangzhou , China Abstract: The aim of the present study was to determine whether angiotensin-converting enzyme inhibitors (ACEI) could contribute to the protective effects of preconditioning, and to explore its underlying mechanism. The Langendorff model of isolated rat heart was used. Cardiac contractility and lactate dehydrogenase (LDH) in the coronary effluent were measured, and infarct area of hearts after 30 min of ischemia followed by 120 min of reperfusion was analyzed. We found that: (1) The subthreshold preconditioning (2 min of ischemia and 10 min of reperfusion), captopril (an ACEI with sulfhydryl groups) or perindoprilate (an ACEI without sulfhydryl groups) alone did not protect the hearts from being injured by 30 min of ischemia and 120 min of reperfusion. (2) However, the combination of captopril or perindoprilate with subthreshold preconditioning could decrease left ventricular end-diastolic pressure (LVEDP), increase left ventricular developed pressure (LVDP) and coronary flow compared with the subthreshold preconditioned group. The combination treatments also inhibited the release of LDH from ischemia/reperfusion hearts, and reduced the infarct area in ischemic heart after 2 h of reperfusion (P<0.05). (3) By using NOS inhibitor L-NAME (100 µmol/l) before combined administration of ACEI with subthreshold preconditioning, the protection effect triggered by the combination treatment was significantly reduced. Pretreatment of the hearts with mitochondrial ATP-sensitive potassium (mitok ATP ) channel inhibitor 5-HD (100 µmol/l) also abolished the protection effect (P<0.05). (4) Subthreshold preconditioning, captopril or perindoprilate alone could enhance the NO content in coronary Received Accepted This work was supported by the Science and Technology Project of Social Development of Huzhou (No. 2004YS18) * Corresponding author. Tel: ; Shenyl@hzcnc.com

2 454 Acta Physiologica Sinica, August 25, 2005, 57(4): effluent (P<0.05), but the combination of captopril or perindoprilate with subthreshold preconditioning could further augment the NO content compared with the subthreshold preconditioned group (P<0.05). The results indicate that ACEIs with or without sulfhydryl groups may potentiate the subthreshold preconditioning to trigger cardiac protection effect against the ischemia/reperfusion injury. This protection effect in the heart is possibly mediated by the generation of NO and the activation of mitok ATP channel. Key words: angiotensin-converting enzyme inhibitors; nitric oxide; mitochondrial ATP-sensitive potassium channel; heart; preconditioning (preconditioning, PC) Murry [1] PC PC [2] [3] [4] (angiotensin-converting enzyme inhibitor, ACEI) PC ACEI ACEI PC 24 h 1,1-diphenyl-2-picryl-hydrazyl B 2 PKC [5] Susie [6] Miki [7] ( ) ACEI B 2 B 2 HOE-140 [8] [9] [10] PC (nitric oxide, NO) [9, 11] ACEI NO NO ATP (ATP-sensitive potassium channel K ATP ) K ATP ATP (mitochondrial ATP-sensitive potassium channel mitok ATP ) ATP (sarcolemmel ATP-sensitive potassium channel sarck ATP ) [12] ( [13] [3] ) mitok ATP sarck ATP [14] ACEI NO mitok ATP ( ) ( ) ACEI NOS L-NAME mitok ATP 5-HD NO mitok ATP ACEI Spague-Dawley (SD) (230~250 g) (captopril Cap) L-NAME 5-HD Sigma (perindoprilat Per) IRIS 1.2 Langendorff SD 4 Krebs-Henseleit (K-H ) Langendorff K-H (76 mmhg) K-H (mmol/l) NaCl KCl 4.7 K 2 PO MgSO NaHCO CaCl ph % O 2 5% CO 2 37 MedLab (left ventricular end-diastolic pressure, LVEDP) (left ventricular developed pressure, LVDP) (+dp/dt max ) ( dp/dt max ) 1.3 Shekher 5 min 25% [5] 1.4 1%

3 : ATP % (TTC) (TTC ph7.8 Na 2 HPO 4 /NaHPO 4 ) 15 min ImageJ ( ) ( + ) [6] 1.5 ( Beckman, CX-4 ) (lactate dehydrogenase, LDH) 1.6 NO NO Griess NO (NO ) (NO ) NO NO NO Griess 546 nm 1.7 SD 12 ( n=7) Langendorff 20 min 30 min 120 min ( 1): A (IS): B (spc): 2 min 10 min C~D (Cap/Per): (200 µmol/l) (100 µmol/l) 20 min E~F (Cap/Per + spc): (200 µmol/l) (100 µmol/l) 8 min ( ) G~H (L-NAME/5-HD + spc): L-NAME (100 µmol/l) 5-HD (100 µmol/l) 10 min K-H 8 min I~L (L-NAME/5-HD + Cap/Per + spc): L-NAME 5-HD 10 min 8 min 1.8 mean SD 1. Fig. 1. Schematic diagram illustrating expermetal protocol.

4 456 Acta Physiologica Sinica, August 25, 2005, 57(4): ONE-way ANOVA SNK min 10 min LDH (P>0.05)( 2~3 2) 2.2 ( 2~4 1~2) spc 120 min LVEDP (P<0.01)( 2) LVDP dp/dt max (P<0.05) ( 3~4 1) LDH spc (P<0.01)( 2) spc LVEDP 90 min (P<0.05)( 2) LVDP (P<0.05)( 3 1) LDH IS (P<0.01)( 2) dp/dt max 2. LVEDP Fig. 2. Alterations of left ventricular end-diastolic pressure (LVEDP) during reperfusion after 30 min of ischemia. mean SD, n = 7. * P<0.05, ** P<0.01 vs spc group; # P <0.05, ## P <0.01 vs Cap + spc group; $ P <0.05 vs Per + spc group.

5 : ATP / Table 1. Recovery of heart rate and coronary flow in the isolated ischemia/reperfusion rat hearts Groups Ischemia Reperfusion HR CF HR CF IS spc Cap Cap + spc ** ** L-NAME + spc L-NAME + Cap + spc ## ## 5-HD + Cap + spc ## ## Per Per + spc * L-NAME + Per + spc $ 5-HD + spc HD + Per + spc $ Ischemia, 30 min after ischemia; Reperfusion,120 min after reperfusion. Heart rate (HR) and coronary flow (CF) are expressed as the percentage of equilibrium values. mean SD, n = 7. * P <0.05, ** P <0.01 vs spc group; ## P <0.01 vs Cap + spc group; $ P <0.05 vs Per + spc group. 2. Table 2. Effect of various interventions on release of myocardial lactate dehydrogenase and infarct size in the isolated rat hearts Groups LDH (U/L) Infarct size/risk area (%) IS spc Cap Cap + spc ** ** L-NAME + spc L-NAME + Cap + spc ## ## 5-HD + Cap + spc ## ## Per Per + spc ** ** L-NAME + Per + spc $ $$ 5-HD + spc HD + Per + spc $ $$ Release of myocardial lactate dehydrogenase (LDH) in the coronary effluent was measured during 5 min of reperfusion after 30 min of ischemia. Infarct size was calculated after 120 min of reperfusion. mean SD, n = 7. ** P <0.01 vs spc group; ## P <0.01 vs Cap + spc group; $ P <0.05, $$ P <0.01 vs Per + spc group. (P>0.05)( 4) 2.3 L-NAME 5-HD L-NAME 5-HD ( 2~4 1~2) L-NAME 5-HD 10 min LVEDP ( 2 P<0.05) LVDP dp/dt max Cap + spc ( 3~4 1 P<0.05) LDH Cap + spc ( 2 P<0.01) 2.4 NO NO IS ( ) µmol/l spc ( ) µmol/l 20 min NO (P<0.05) Cap + spc Per + spc NO (P<0.01) NO (

6 458 Acta Physiologica Sinica, August 25, 2005, 57(4): LVDP Fig. 3. Recovery of left ventricular developed pressure (LVDP) during reperfusion after 30 min of ischemia. mean SD, n=7. * P <0.05, ** P <0.01 vs spc group; # P <0.05, ## P <0.01 vs Cap + spc group; $ P <0.05 vs Per + spc group. 5 P<0.05) 3 ACEI( ) ACEI Susie [6] Miki [7] ( ) ACEI PKC PKC [10] Qiu [15] Shinmura [16] NO NO L- [17] L-NAME [18] NOS L-NAME cnos inos NO [9] NO

7 : ATP dp/dt max Fig. 4. Recovery of dp/dt max at the end of 120 min of reperfusion after 30 min of ischemia. mean SD, n = 7. ** P <0.01 vs spc group, ## P <0.01 vs Cap + spc group. 5. NO Fig. 5. Release of NO in coronary effluent before 30 min of ischemia. mean SD, n = 6. * P <0.05, ** P <0.01 vs IS group. [19] L-NAME [10, 20] 2~3 h 24 h 72 h 24 h L-NAME [5] L-NAME ACEI NO NO ACEI NO NO NO mitok ATP 5-HD Sargent ACE zofenopril n-acetyl cysteine K ATP K ATP cromakalin zofenopril [21]

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Activation of mitochondrial ATP-sensitive potassium channels delays ischemia-induced cellular uncoupling in rat heart 1

22 2004, Acta Pharmacologica Sinica Chinese Pharmacological Society Shanghai Institute of Materia Medica Chinese Academy of Sciences http://www.chinaphar.com Activation of mitochondrial ATP-sensitive potassium