Effects of a Selective Protein Kinase C beta II Peptide Inhibitor on Real-Time Blood Nitric Oxide and Hydrogen Peroxide Release in Femoral Artery/Vein Ischemia and Meperfusion

摘要

Vascular endothelial dysfunction is a key component initiating oxidative stress in ischemia/reperfusion (I/R). Endothelial dysfunction is characterized by an increase in hydrogen peroxide (H2O2) and a decrease in the bioavailability of endothelial-derived nitric oxide (NO). When activated, protein kinase C (PKC) stimulates superoxide (SO) and subsequent H2O2 release from NADPH oxidase in both leukocytes/endothelial cells and inhibits endothelial nitric oxide synthase (eNOS) causing an increase in oxidative stress (Figure 1). Previous studies using a broad-spectrum PKC inhibitor Go 6983 (mol. wt. 442) or selective PKC Beta (p) II peptide inhibitor (N-Myr-SLNPEWNET mol. wt. 1300) improved cardiac function in myocardial I/R (ex vivo), decreased leukocyte-endothelial interactions (in vivo)/leukocyte superoxide (SO) release (in vitro) and increased endothelial-derived NO release (in vitro) [1,2]. PKC βII peptide inhibitor works by binding to the receptor for activated kinase (RACK-1) and attenuates the translocation of PKC βII to the cell membrane. By contrast. Go 6983 inhibits the ATP binding site of PKC. The attenuation of PKC activity by these mechanisms in turn decreases PKC phosphorylation of substrates (i.e. NADPH oxidase and eNOS). Collectively, this results in attenuating SO thereby inhibiting SO release from NADPH oxidase and increasing eNOS activity to enhance NO release, both of which reduces oxidative stress in I/R injury.