Effects of Modulating eNOS Activity on Leukocyte-Endothelial Interactions in Rat Mesenteric Postcapillary Venules

摘要

Inflammation following vascular endothelial dysfunction is a common feature for the pathogenesis of various vascular diseases, such as ischemia/reperfusion injury, hypertension and atherosclerosis. Normally, vascular endothelium maintains an anti-thrombotic and antiinflammatory surface to facilitate blood flow principally by producing endothelial-derived nitric oxide (NO). Endothelial NO synthase (eNOS) produces NO from L-arginine in the presence of the essential cofactor tetrahydrobiopterin (BH4). Under oxidative stress, BH4 is oxidized to dihydrobiopterin (BH2), and the ratio of BH2/BH4 is increased," eNOS is enzymatically uncoupled, producing superoxide (SO) instead of NO because molecular oxygen, rather than L-arginine, accepts the electron [1]. Our previous studies have shown that administration of BH2 promotes leukocyte-endothelial interactions in the mesenteric circulation in vivo [2]. To better understand the roles of coupled/uncoupled eNOS activity in inflammation, eNOS modulators, protein kinase C epsilon (PKC 8) peptide activator (+) or inhibitor (-) was administered with BH4 or BH2 to evaluate leukocyte-endothelial interactions in vivo. PKC e increases eNOS activity via nhosohorvlation of eNOS serine 1177 [3]. We hypothesized that PKC g+ (N-Myr-HDAPIGYD, MW=1097 g/mol, Genemed Synthesis Inc., San Antonio, TX) combined with BH2 would result in increased uncoupled eNOS activity and thus augment or sustain the BH2-induced leukocyte-endothelial interactions, while PKC s+ combined with BH4 would attenuate BH2-induced inflammation. In contrast, PKC s-(N-Myr-EAVSLKPT, MW=1054 g/mol), Genemed Synthesis Inc.) will attenuate BH2 induced inflamma-tion in the presence or absence of Fig. I. The hypothesis diagram. BH4 (Figure 1).