20-Hydroxyeicosatetraenoic acid induces apoptosis in neonatal rat cardiomyocytes through mitochondrial-dependent...

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.

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.

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.