Relationship between hypoxia-induced apoptosis and caspases-3 activation, intracellular calcium overload in cardiomyocytes / 中国应用生理学杂志

ABSTRACT

<p><b>AIM</b>To explore the effects of hypoxia on Caspases activation in cardiomyocyte and role of intracellular calcium in this event in cardiomyocytes.</p><p><b>METHODS</b>After hypoxia 0 min, 30 min, 1 h, 3 h, 6 h, 12 h, 24 h, apoptotic cell percentage was determined with Hoechst 33342 straining. Expressions of Caspases-3 mRNA and release of mitochondrial cytochrome c in primary culture of cardiomyocytes were determined by using RT-PCR and Western blotting respectively.</p><p><b>RESULTS</b>Elevation of Cyt c in cytosol was in accordance with the decline in mitochondrial Cyt c content. Significant increase in Cyt c in cytosol appeared at 12 h post hypoxia and peaked at 24 h while Cyt c in mitochondria could not be detected at 24 h post hypoxia. Hypoxia up-regulated Caspases-3 mRNA expressions beginning at 3 h post hypoxia. Intracellular calcium overload occurred earlier than release of mitochondrial Cyt c and the activation of Caspase-3 during the hypoxic insult. Inhibition of Caspase-3 activation and pretreatment with calcium chelator BAPTA/AM offered a marked protective effect on hypoxia induced cardiomyocyte apoptosis.</p><p><b>CONCLUSION</b>Hypoxia can induce mitochondrion-dependent Caspase-3 activation in cardiomyocytes and therefore leads to cell apoptosis. Increase of intracellular Ca2+ plays an important role in the activation of Caspase-3 and the induction of apoptosis in cardiomyocytes.</p>