Endothelial NO Synthase (eNOS) phosphorylation regulates coronary diameter during ischemia-reperfusion in association with oxidative stress.

Abstract

The link between endothelial nitric oxide synthase (eNOS) activation and vascular diameter during ischemia-reperfusion was investigated in the rat heart. After short (<30 min) and long (>45 min) time of ischemia conferred by coronary artery occlusion of the rats, reperfusion caused dilatation and constriction of arterioles, respectively. Partial oxygen pressure (pO2) measurement of the heart by the electrode confirmed the hyper-perfusion and no-reflow phenomena during reperfusion, as well as myocardial ischemia. The vascular diameter was correlated with phosphorylation of Akt and serine 1177 residue of eNOS, and formation of NO-bound guanylate cyclase (GC) by immuoflorescence study. Western blotting confirmed the phosphorylation of eNOS-Ser1177 depending on ischemia time. The constriction during reperfusion after 45 min of ischemia is supposedly caused by the inhibition of Akt-mediated eNOS-Ser1177 phosphorylation, which was suppressed by a PKC inhibitor chelerythrine, or ROS scavengers N-2-mercaptopropionyl glycine (MPG) and 4,5-Dihydroxy-1, 3-benzenedisulfonic acid disodium salt (Tiron). However, an endothelin receptor antagonist BQ123 alleviated the vasoconstriction by increasing NO availability but not eNOS-Ser1177 phosphorylation. Thus, vascular patency is correlated with eNOS-Ser1177 phosphorylation in association with ROS, and PKC during reperfusion. Endothelin inhibits vasodilatation by reducing NO availability during reperfusion.

• Authors: Sumihisa Hoshino, Yousuke Kikuchi, Makoto Nakajima, Hiroko Kimura, Shingo Tsuyama, Koichi Uemura, Ken-Ichi Yoshida
• Journal: Free radical research (Free Radic Res) Vol. 39 Issue 5 Pg. 481-9 (May 2005) ISSN: 1071-5762 [Print] England
• PMID: 16036323 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Endothelins
• Enzyme Inhibitors
• Reactive Oxygen Species
• Nitric Oxide Synthase
• Nitric Oxide Synthase Type III
• Nos3 protein, rat
• Protein Kinase C

Topics

• Animals
• Blotting, Western
• Coronary Vessels (enzymology)
• Endothelins (metabolism)
• Enzyme Activation (physiology)
• Enzyme Inhibitors (pharmacology)
• Fluorescent Antibody Technique
• Heart (drug effects)
• Male
• Myocardium (enzymology, pathology)
• Nitric Oxide Synthase (metabolism)
• Nitric Oxide Synthase Type III
• Oxidative Stress (physiology)
• Phosphorylation
• Protein Kinase C (metabolism)
• Rats
• Reactive Oxygen Species (metabolism)
• Reperfusion Injury (enzymology)
• Vasoconstriction (drug effects, physiology)