VEGF Regulation of eNOS Phosphorylation Is Involved in Isoflurane Cardiac Preconditioning.

Aims: Previous studies indicate that nitric oxide derived from endothelial nitric oxide synthase (eNOS) serves as both trigger and mediator in anesthetic cardiac preconditioning. The mechanisms underlying regulation of eNOS by volatile anesthetics have not been fully understood. Therefore, this study examined the role of vascular endothelial growth factor (VEGF) in isoflurane cardiac preconditioning.

Methods and results: Wistar rats underwent 30 min of coronary artery occlusion followed by 2 h of reperfusion. Isoflurane given prior to ischemia/reperfusion significantly decreased myocardial infarct size from 60 ± 1% in control to 40 ± 3% (n = 8 rats/group, P < 0.05). The beneficial effects of isoflurane was blocked by neutralizing antibody against VEGF. Coronary arterial endothelial cells alone or together with cardiomyocytes were subjected to hypoxia/reoxygenation injury. The expression of VEGF and eNOS was analyzed by Western blot, and nitric oxide was measured by ozone-based chemiluminescence. In co-cultured cardiomyocytes and endothelial cells, isoflurane administered before hypoxia/reoxygenation attenuated lactate dehydrogenase activity and increased the ratio of phosphorylated eNOS/eNOS and nitric oxide production. The protective effect of isoflurane on cardiomyocytes was compromised by neutralizing antibody against VEGF and after VEGF in endothelial cells was inhibited with hypoxia inducible factor-1α shRNA. The negative effect of hypoxia inducible factor-1α shRNA was restored by recombinant VEGF.

Conclusion: Isoflurane cardiac preconditioning is associated with VEGF regulation of phosphorylation of eNOS and nitric oxide production.