20-Hydroxyeicosatetraenoic Acid Induces Apoptosis in Neonatal Rat Cardiomyocytes Through Mitochondrial-Dependent Pathways

Objective: 20-Hydroxyeicosatetraenoic acid (20-HETE), a omega-hydroxylation product of arachidonic acid catalyzed by cytochrome P450 4A, may play a role in the cardiovascular system. It is well known that cytochrome P450 omega-hydroxylase inhibitors markedly reduced the cardiac ischemia reperfusion injury. However, the direct effect of 20-HETE on cardiomyocytes is still poorly investigated. Here, we studied the effect of 20-HETE on cardiomyocyte apoptosis and the apoptosis-associated signaling pathways. Methods and Results: The cardiomyocyte apoptosis was measured by fluorescein isothiocyanate conjugated annexin V/propidium iodide double staining cytometry, indicating that the percentage of early apoptotic cells increased from 15.6% +/- 2.6% to 25.5% +/- 2.5% in control and 20-HETE-treated cells, respectively. The mitochondrial membrane potential (Delta Psi m) was measured by detecting the ratio of JC-1 green/red emission intensity. A significant decrease in the ratio was observed after treatment with 20-HETE for 24 hours in comparison with control group, suggesting the disruptive effect of 20-HETE on mitochondrial Delta Psi m. In addition, 20-HETE stimulated caspase-3 activity and Bax mRNA expression in cardiomyocytes. In contrast, the Bcl-2 mRNA levels were significantly decreased by 20-HETE treatment. Conclusion: These results demonstrate that 20-HETE induces cardiomyocyte apoptosis by activation of several intrinsic apoptotic pathways. The 20-HETE-induced apoptosis could contribute to the cytochrome P450 omega-hydroxylase-dependent cardiac injure during cardiac ischemia-reperfusion.