Isoflurane preconditioning protects cardiomyocytes against hypoxia/reoxygenation injury via a vascular endothelial growth factor-dependent mechanism

Abstract

Isoflurane preconditioning (IsoPC) has been demonstrated to exert a cardioprotective effect. We aimed to examine the role of vascular endothelial growth factor (VEGF) during cardiomyocyte protection produced by IsoPC. Human coronary endothelial cells(ECs) were co-cultured with cardiomyocytes isolated from neonatal rats. The co-culture underwent 2 hours of hypoxia followed by 2 hours of reoxygenation in the presence or absence of isoflurane administered 60 mins prior to hypoxia. IsoPC significantly increased the production of nitric oxide from ECs and decreased the levels of lactate dehydrogenase release. The beneficial effect of IsoPC on cardiomyocytes was blocked by VEGF neutralizing antibody applied prior to IsoPC. To examine whether VEGF is a downstream target of hypoxia-induced factor 1α (HIF1α), ECs were infected with lentivirus containing shRNA against HIF1α for 72 hours prior to co-culture. The expression of total VEGF and VEGF receptor 2 proteins was significantly decreased by HIF1α knockdown. IsoPC failed to protect cardiomyocyte against hypoxia/reoxygenation (H/R) injury in HIF1α knockdown ECs. The detrimental effect of HIF1α silencing on IsoPC was restored by administration of recombinant VEGF during the period of co-culturing. These results demonstrate that VEGF plays a critical role in cardiomyocyte protection against H/R injury. During IsoPC, VEGF may be a downstream mediator of HIF1α.