Effects of α-lipoic acid on ischemia-reperfusion-induced renal dysfunction in rats

Abstract

We investigated whether α-lipoic acid (α-LA), an antioxidant, attenuates the ischemia-reperfusion (I/R)-induced dysregulation of these transporters. Both renal pedicles of male Sprague-Dawley rats were clamped for 40 min. α-LA (80 mg/kg) was administered intraperitoneally before and immediately after induction of ischemia. After 2 days, the expression of aquaporins (AQPs), sodium transporters, and nitric oxide synthases (NOS) was determined in the kidney by immunoblotting and immunohistochemistry. The expression of endothelin-1 (ET-1) mRNA was determined by real-time PCR. Activities of adenylyl cyclase and guanylyl cyclase were measured by stimulated generation of cAMP and cGMP, respectively. The expression of AQP1–3 as well as that of the α1-subunit of Na-K-ATPase, type 3 Na/H exchanger, Na-K-2Cl cotransporter, and Na-Cl cotransporter was markedly decreased in response to I/R. The expression of type VI adenylyl cyclase was decreased in I/R-injured rats, which was counteracted by the treatment of α-LA. AVP-stimulated cAMP generation was blunted in I/R rats and was then ameliorated by α-LA treatment. α-LA treatment attenuated the downregulation of AQPs and sodium transporters. The expression of endothelial NOS was decreased in I/R rats, which was prevented by α-LA. The cGMP generation in response to sodium nitroprusside was blunted in I/R rats, which was also significantly prevented by α-LA. The mRNA expression of ET-1 was increased, which was recovered to the control level by α-LA treatment. In conclusion, α-LA treatment prevents I/R-induced dysregulation of AQPs and sodium transporters in the kidney, possibly through preserving normal activities of local AVP/cAMP, nitric oxide/cGMP, and ET systems.