Abstract
Recently we have demonstrated that in HeLa cells staurosporine (STS) rapidly exhibits the apoptotic volume decrease by activation of volume-sensitive outwardly rectifying Cl− channels in a manner dependent on reactive oxygen species (ROS) and that STS-induced apoptosis of the cells is rescued by a Cl− channel blocker or a ROS scavenger (PNAS 101, 6770, 2004). In the present study, thus, we examined whether apoptosis of cardiomyocytes induced by ischemia/reperfusion (I/R) is also dependent on the Cl− channel and ROS. Neonatal mouse cardiomyocytes in primary culture were subjected to the I/R stress by incubating for 6 h under the hypoxic and glucose-free conditions followed by culturing for 96 h in the presence of oxygen and glucose. By this I/R stress, reduction of cell viability, DNA laddering and caspase-3 activation were induced. When a Cl− channel blocker (DIDS or NPPB) was applied for the R period (but not the I period), cardiomyocyte apoptosis was largely prevented. A ROS scavenger (Tiron, N-acetylcysteine or catalase) was also effective in rescuing the cells from apoptosis when applied during reperfusion. In addition, a large amount of ROS was found to be produced upon reperfusion. These results suggest that I/R-induced cardiomyocyte apoptosis involves the Cl− channel activity and the action of ROS produced upon reperfusion. [Jpn J Physiol 55 Suppl:S75 (2005)]
