Hydrogen peroxide derived from Nox‐2 mediates protein kinase C‐induced contraction of bovine coronary artery and mouse aorta

Abstract

Activation of protein kinase C (PKC) is known to stimulate NAD(P)H oxidase-derived superoxide and hydrogen peroxide (H2O2). In this study, we investigated which oxidase participates in increasing H2O2 levels and force generation by PKC activation. Stimulation of PKC by phorbol-12,13-dibutyrate (PDBu: 10 uM) increased superoxide levels by 4-fold and force generation to levels generated by 30 mM KCl in endothelium-removed bovine coronary arteries (BCA). Force generation elicited by PDBu was partially Ca2+-dependent, because PDBu-induced contraction was suppressed by 45.6% in Ca2+ free Krebs solution. In contrast, superoxide generation by PKC activation was Ca2+-independent. However, PKC-elicited BCA contraction was partially inhibited (42%) by a NADPH oxidase inhibitor, gp91dstat (50 uM). Moreover, gp91dstat inhibited PDBu-elicited contraction of Wild-type aorta by 85%; whereas PDBu did not induce contraction in gp91phox knockout mice aorta. Therefore, our data indicate that H2O2 derived from Nox-2 mediates PKC-induced contraction of bovine coronary artery and mouse aorta. (Supported by NIH grants HL 31069, HL43023, HL66331).