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Preventive effect of endothelia 1 pretreatment on hypoxix induced injury in cultured neonatal rat cardiomyoc尹e

PAN Yan Xia, Lin Li, YUAN Weir Jun, WU Guo-Hong, TANG CHAO-SHU

'Department of Physiology, Second Military Medical University, Shanghai 200433；Department of Physiology, Fujian Medical University, Fuzhou 350004；Department of Physiology and Pathophysiology，Health Sciences Center，Peking University，Beijing 100083

Abstract

This study was designed to observe the effects of endothelixrl(ET-1)pretreatment on hypoxia7induced injury and changes in[Ca~(2+)]，in cultured neonatal rat cardiomyocytes .The activity of lactate dehydrogenase(LDH) and superoxide dis mutase(S OD)，and the content of malondialdehyde
(MDA) in the supernatant were determined in the cultured cardiomyocytes su匀ected to a 12-h hypoxia induced by a 3q一5 % Cq atmosphere at 37℃with or without ET-1 pretreatment.[Ca~(2+)]，was measured with Ca~(2+)sensitive fluorescent probe fluo-3/ AM under a laser scanning confocal microscope .Fluo-
rescence intensity emitted from fluo-3/ AM-loaded cells reflected the concentration of[Ca~(2+)]，.The hypoxia model used in[Ca~(2+)]，measurement was established by continously perfusing cardiomyocytes for 30 min with 95%NZ 5%CO2 saturated D ME M solution containing 1 m mol/ L Na2S2 04.Pretreatment with ET-1 consisted of three cycles of ET-1 perfusion(5 min for each) followed by E T-1一free DME M solution (1 0 min for each) prior to hypoxia .The results showed that(1)after incubation in a 3%02 -5%C02 hypoxic atmosphere for 1 2 h，the activity of LDH and the content of MDA in the supernatant significant-
1y increase dfrom 19.33士1.03 U/ L to 43. 33士1.21 U/ L and from 0. 91士0. 03 nmol/ L to 1.71士0. 02nmol/ L，respectively，whereas the activity of SOD decreased from 33.48士1.15 U/ ml to 16. 93士1.11U/ ml(P<0. 01)·In hypoxic cardiomyocytes pretreated with 0. 01一1 nmol/ L ET-1，LDH release and
supernatant MDA content were decreased，while SOD activity was enhanced dose-dependently(P<0. 01).(2) The spontaneous calcium transient in cultured cardiomyocytes terminated at 29士1.5 s and [Cat十]，increased by 107士13.2 % during perfusion of hypoxic solution(P<0. 001)at the end of 30 min .ET-1(0. 01一1 nmol/ L) increased the frequency of[Ca~(2+)]，transient in cultured cardiomyocytes in a dose-dependent manner(P<0.01).The termination of[Ca~(2+)]，transient and the elevation of[Cat十]1caused by hypoxia were postponed by pretreatment with 0. 01一1 nmol/ L ET -I(P<0. 01).These results show that pretreatment with 0. 01一1 nmol/ L ET-1 attenuates hypoxia7induced injury and[Cat十]1changes in cultured neonatal cardiomyocytes，indicating a cytoprotective role of ET-1 pretreatment.

Key words: hypoxia;cardiomyocytes;intracellular calcium ;

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Citing This Article：

PAN Yan Xia, Lin Li, YUAN Weir Jun, WU Guo-Hong, TANG CHAO-SHU. Preventive effect of endothelia 1 pretreatment on hypoxix induced injury in cultured neonatal rat cardiomyoc尹e. Acta Physiol Sin 2003; 55 (2): (in Chinese with English abstract).