Protective effect of ischemic preconditioning on ischemia/reperfusion-induced acute kidney injury through sympathetic nervous system in rats.

We have found that a series of brief renal ischemia and reperfusion (preconditioning), before the time of ischemia significantly attenuated the ischemia/reperfusion-induced acute kidney injury through endothelial nitric oxide synthase. In this study, we examined the effects of ischemic preconditioning on renal sympathetic nervous system and kidney function in ischemia/reperfusion-induced acute kidney injury with or without nitric oxide synthase inhibitor. Ischemia/reperfusion-induced acute kidney injury was made by clamping the left renal artery and vein for 45-min followed by reperfusion, 2 weeks after the contralateral nephrectomy. Ischemic preconditioning, consisting of three cycles of 2-min ischemia followed by 5-min reperfusion, was performed before the 45-min ischemia. Ischemic preconditioning suppressed the enhanced renal sympathetic nerve activity during ischemia and the elevated renal venous plasma norepinephrine level after reperfusion, and attenuated renal dysfunction and histological damage. The renoprotective effect of ischemic preconditioning was diminished by N(G)-nitro-L-arginine methyl ester (0.3 mg/kg, i.v.), a nonselective nitric oxide synthase inhibitor, 5 min before the start of ischemic preconditioning. Thus, ischemic preconditioning decreased renal sympathetic nerve activity and norepinephrine release probably through activating nitric oxide production, thereby improving ischemia/reperfusion-induced acute kidney injury.