In our model, I/R injury significantly reduced Mn SOD and Cu/Zn SOD mRNA expression, resulting in increased superoxide, and caused oxidative stress

In our model, I/R injury significantly reduced Mn SOD and Cu/Zn SOD mRNA expression, resulting in increased superoxide, and caused oxidative stress. surgery. MnTMPyP significantly attenuated the I/R-mediated increase in serum creatinine levels and decreased tubular epithelial cell damage following I/R. MnTMPyP also decreased TNF- levels, gp91phox, and lipid peroxidation after I/R. Furthermore, MnTMPyP inhibited the I/R-mediated increase in apoptosis and caspase-3 activation. Interestingly, although MnTMPyP did not increase expression of the antiapoptotic protein Bcl-2, it decreased the expression of the proapoptotic genes Bax and FasL. These results suggest that MnTMPyP is effective in reducing apoptosis associated with renal I/R injury and that multiple signaling mechanisms are involved in ROS-mediated cell death following renal I/R injury. Keywords:acute ischemia-reperfusion, manganese(III) tetrakis(1-methyl-4-pyridyl)porphyrin, reactive oxygen species renal ischemia-reperfusion(I/R) injury continues to be a significant and persistent problem in kidney transplantation, with serious consequences (8). I/R induces some injury in the cortical proximal tubules and a more severe, generally lethal injury in the outer medullary proximal tubules (8). Apoptosis has been shown to be the major mechanism leading to tubule cell death during the early ischemic renal injury phase (14,45), and the generation of reactive oxygen species (ROS) plays an important role in this process (26,27). These free radicals can attack a wide variety of cellular components including DNA, proteins, and lipids, leading to DNA and protein oxidation, protein degradation and lipid peroxidation and thereby enhancing the destruction of the cell structure and loss of cell function (3). ROS also increase the production of proinflammatory cytokines in I/R that can further accelerate apoptotic signaling and cellular damage (51). Since multiple factors are involved in renal Rabbit polyclonal to ANKRA2 I/R injury cascades, it is important to identify the underlying mechanisms and pathways that ultimately lead to the loss of kidney function. In vivo studies have shown that resistance to renal I/R injury is partly due to a decrease in oxidative stress and preservation of antioxidant proteins (5,38). Manganese superoxide dismutase (Mn SOD) and copper/zinc superoxide dismutase (Cu/Zn SOD) both protect against global cerebral ischemia by preventing early DNA fragmentation (17,18). Furthermore, SOD mimetics have also been shown to be protective against cell injury caused by ROS in models of ischemic injury (15,43), and MnTMPyP attenuates lipopolysaccharide (LPS)-induced production of superoxide (O2) and prostaglandin E2(PGE2) in microglia (50). We showed previously (33) that MnTMPyP, a cell-permeant SOD mimetic, rescues renal proximal tubular epithelial cells from ATP depletion-mediated apoptosis. However, whether MnTMPyP Secalciferol can protect the kidney from acute renal I/R injury in vivo and whether the mechanisms are similar to the in vitro cell culture model are still unclear. The present study tested our hypothesis that MnTMPyP protects the kidney from renal I/R injury-mediated damage in vivo. We measured kidney function, markers of apoptosis, and oxidative stress following renal I/R injury. Finally, to determine the mechanism of action of MnTMPyP we examined the extrinsic and intrinsic pathways of apoptosis following renal I/R injury. == METHODS == == Animal model of renal I/R injury. == Male Sprague-Dawley rats (175220 g) were purchased from Harlan. All experiments were approved by the Animal Care and Use Committee at the Medical College of Wisconsin. The animals were anesthetized with pentobarbital sodium (50 mg/kg ip). Renal I/R was induced by bilateral clamping of the Secalciferol renal arteries for 45 Secalciferol min followed by revascularization for 24 h. A subset of animals were treated with either MnTMPyP (5 mg/kg ip, 30 min before surgery and 6 h after reperfusion) or saline vehicle. Sham-operated control animals underwent surgery without renal artery clamping. Animals were killed at the end of 24 h, and kidneys were isolated, quick frozen in liquid nitrogen, and stored at 80C until further analysis. Blood was sampled with heparinized syringes and centrifuged for 1.