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Effects of endothelin‐1 antagonist BQ610 on hypoxia‐induced injury and [Ca 2+ ] i changes in cultured neonatal rat cardiomyocytes
Author(s) -
Lin Li,
Yuan WenJun
Publication year - 2003
Publication title -
drug development research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.582
H-Index - 60
eISSN - 1098-2299
pISSN - 0272-4391
DOI - 10.1002/ddr.10134
Subject(s) - hypoxia (environmental) , lactate dehydrogenase , endocrinology , medicine , chemistry , endothelin 1 , antagonist , endogeny , endothelin receptor , calcium , superoxide dismutase , ischemia , receptor , biology , biochemistry , oxygen , enzyme , organic chemistry
Hypoxia is a strong stimulus for endothelin‐1 (ET‐1) synthesis, which is involved in myocardial ischemia. To shed light on the role and calcium mechanism of endogenous ET‐1 in myocardial ischemia, the effects of the ET‐1 antagonist BQ610 on hypoxia‐induced injury and [Ca 2+ ] i changes were observed in cultured neonatal rat cardiomyocytes. Hypoxia‐induced injury was assessed by determining supernatant activity of lactate dehydrogenase (LDH) and superoxide dismutase (SOD) in cardiomyocytes exposed to hypoxia produced by a 3% O 2 , 5% CO 2 atmosphere. [Ca 2+ ] i was measured with the Ca 2+ ‐sensitive dye Fluo‐3 under a confocal microscope. The hypoxia model used for [Ca 2+ ] i measurement was prepared by perfusing cells with 95% N 2 , 5% CO 2 saturated DMEM solution containing 1 mM Na 2 S 2 O 4 . The results showed that: 1) Hypoxia significantly increased ET‐1 content in culture supernatant. 2) The supernatant LDH was significantly increased after 12‐ or 24‐h hypoxia. On the other hand, SOD activity was decreased significantly. BQ610 0.2–5 µM dose‐dependently reduced LDH release and enhanced SOD activity. 3) [Ca 2+ ] i transient was observed in the normal cultured beating cardiomyocytes. Exposure to hypoxia caused termination of [Ca 2+ ] i transient in 3–5 min and a continuous rapid increase in [Ca 2+ ] i after about 20 min. In the presence of BQ610, the termination of [Ca 2+ ] i transient was postponed to 15–20 min into hypoxia; the [Ca 2+ ] i increase was rather slow until approximately 45 min into hypoxia. These results indicate that endogenous ET‐1 contributed to hypoxia‐induced injury in the cultured neonatal rat cardiomyocytes and that the injury was associated with a [Ca 2+ ] i mechanism partially mediated by ET‐1. Drug Dev. Res. 58:74–78, 2003. © 2003 Wiley‐Liss, Inc.