Reactive Oxygen Species–Induced Stimulation of 5AMP-Activated Protein Kinase Mediates

Background—5AMP-activated protein kinase (AMPK), a well-known regulator of cellular energy status, is also implicated in ischemic preconditioning leading to cardioprotection. We hypothesized that AMPK is involved in anesthetic-induced cardioprotection and that this activation is mediated by reactive oxygen species (ROS). Methods and Results—Isolated Langendorff-perfused rat hearts were subjected to 35 minutes of global ischemia (I) followed by 120 minutes of reperfusion (I/R). Hearts were assigned to a control group (Con) or a sevoflurane (Sevo) group receiving 3 times 5-minute episodes of sevoflurane (2.5vol%) before I/R. Phosphorylation of both AMPK and endothelial nitric oxide synthase (eNOS) were determined by Western blot analysis. Cardioprotection was assessed after I/R from recovery of left ventricular pressure and from infarct size (triphenyltetrazolium chloride staining). In the control group, ischemia resulted in a 2-fold increase in phosphorylation levels of AMPK (Con 0.130.01 versus Con-I 0.280.05, P0.05), which was sustained after 120 minutes of reperfusion (Con-I/R 0.260.02, P0.05). Sevoflurane preconditioning had no affect on AMPK phosphorylation before ischemia (Sevo 0.120.03, P0.05), but almost doubled the increase in AMPK phosphorylation relative to control after ischemia (Sevo-I 0.480.09, P0.05), an effect that was sustained after reperfusion (Sevo-I/R 0.490.12, P0.05). The AMPK-inhibitor compound C (10 mol/L) reduced the sevoflurane-mediated increase in phosphorylation of AMPK and its target eNOS and abolished cardioprotection. The ROS-scavenger n-(2-mercaptopropionyl)-glycine (1 mmol/L) blunted the sevoflurane-mediate