The role of
protein kinase C epsilon (
PKC epsilon) in polymorphonuclear leukocyte (PMN)-induced
myocardial ischemia/reperfusion (MI/R) injury and novel-related mechanisms, such as regulation of vascular endothelium
nitric oxide (NO) and
hydrogen peroxide (H2O2) release from blood vessels, have not been previously evaluated. A cell-permeable
PKC epsilon peptide activator (1-10 microM) significantly increased endothelial NO release from non-ischemic rat aortic segments (p < 0.01). By contrast,
PKC epsilon peptide inhibitor (1-10 microM) dose-dependently decreased NO release (p < 0.01). Then, these corresponding doses of
PKC epsilon activator or inhibitor were examined in MI/R. The
PKC epsilon inhibitor (5 microM given during reperfusion, n=6) significantly attenuated PMN-induced postreperfused cardiac contractile dysfunction and PMN adherence/infiltration (both p < 0.01), and expression of intracellular adhesion molecule-1 (ICAM-1; p < 0.05). By contrast, only
PKC epsilon activator pretreated hearts (5 muM
PKC epsilon activator given before
ischemia (PT), n = 6), not
PKC epsilon activator given during reperfusion (5 microM, n=6) exerted significant cardioprotection (p < 0.01). Moreover, the
NO synthase inhibitor,
N(G)-nitro-L: -arginine methyl ester, did not block the cardioprotection of
PKC epsilon inhibitor, whereas it completely abolished the cardioprotective effects of
PKC epsilon activator PT. In addition,
PKC epsilon inhibitor (0.4 mg/kg) significantly decreased H(2)O(2) release during reperfusion in a femoral I/R model (p < 0.01). Therefore, the cardioprotection of
PKC epsilon inhibitor maybe related to attenuating
ICAM-1 expression and H2O2 release during reperfusion. By contrast, the cardioprotective effects of
PKC epsilon activator PT may be mediated by enhancing vascular endothelial NO release before
ischemia.