Involvement of protein kinase C in angiotensin II-mediated release of 12-hydroxyeicosatetraenoic acid in bovine adrenal glomerulosa cells.

The present study was conducted to determine whether protein kinase C was involved in angiotensin II-mediated release of 12-hydroxyeicosatetraenoic acid (12-HETE) from bovine adrenal glomerulosa cells. Activators of protein kinase C, 12-O-tetradecanoylphorbol 4-acetate (TPA) and 1-oleoyl-2-acetylglycerol (OAG), significantly increased release of 12-HETE. The effect of OAG was potentiated by BAYK8644, a stimulator of calcium entry. Sphingosine, H-7 and staurosporine, which inhibited the activity of protein kinase C in vitro, almost completely blocked 12-HETE release induced by TPA. These agents also significantly reduced angiotensin II-mediated 12-HETE release. When time course of the liberation of 12-HETE was measured, angiotensin II elicited sustained release of 12-HETE, which was inhibited by staurosporine. These results indicate that angiotensin II induces sustained release of 12-HETE, a feed forward regulator of aldosterone secretion, and that protein kinase C may be involved in this process.