Ischemia-reperfusion reduces cystathionine-β-synthase-mediated hydrogen sulfide generation in the kidney

Xu Z, Prathapasinghe G, Wu N, Hwang SY, Siow YL, O K. Ischemia-reperfusion reduces cystathionine-beta-synthase-mediated hydrogen sulfide generation in the kidney. Am J Physiol Renal Physiol 297: F27-F35, 2009. First published May 13, 2009; doi: 10.1152/ajprenal. 00096.2009.-Cystathionine-beta-synthase (CBS) catalyzes the rate-limiting step in the transsulfuration pathway for the metabolism of homocysteine (Hcy) in the kidney. Our recent study demonstrates that ischemia-reperfusion reduces the activity of CBS leading to Hcy accumulation in the kidney, which in turn contributes to renal injury. CBS is also capable of catalyzing the reaction of cysteine with Hcy to produce hydrogen sulfide (H2S), a gaseous molecule that plays an important role in many physiological and pathological processes. The aim of the present study was to examine the effect of ischemia-reperfusion on CBS-mediated H2S production in the kidney and to determine whether changes in the endogenous H2S generation had any impact on renal ischemia-reperfusion injury. The left kidney of Sprague-Dawley rat was subjected to 45-min ischemia followed by 6-h reperfusion. The ischemia-reperfusion caused lipid peroxidation and cell death in the kidney. The CBS-mediated H2S production was decreased, leading to a significant reduction in the renal H2S level. The activity of cystathionine-gamma-lyase, another enzyme responsible for endogenous H2S generation, was not significantly altered in the kidney upon ischemia-reperfusion. Partial restoration of CBS activity by intraperitoneal injection of the nitric oxide scavenger, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide not only increased renal H2S levels but also alleviated ischemia-reperfusion-induced lipid peroxidation and reduced cell damage in the kidney tissue. Furthermore, administration of an exogenous H2S donor, NaHS (100 mu g/kg), improved renal function. Taken together, these results suggest that maintenance of tissue H2S level may offer a renal protective effect against ischemia-reperfusion injury.