, a cell-permeant SOD mimetic, reduces oxidative stress and apoptosis following renal ischemia-reperfusion. Am J Physiol Renal Physiol 296: F266 -F276, 2009. First published December 17, 2008 doi:10.1152/ajprenal.90533.2008.-Oxidative stress and apoptosis are important factors in the etiology of renal ischemia-reperfusion (I/R) injury. The present study tested the hypothesis that the cell-permeant SOD mimetic manganese(III) tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP) protects the kidney from I/R-mediated oxidative stress and apoptosis in vivo. Male Sprague-Dawley rats (175-220 g) underwent renal I/R by bilateral clamping of the renal arteries for 45 min followed by reperfusion for 24 h. To examine the role of reactive oxygen species (ROS) in renal I/R injury, a subset of animals were treated with either saline vehicle (I/R Veh) or MnTMPyP (I/R Mn) (5 mg/kg ip) 30 min before and 6 h after 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, gp 91phox , 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. acute ischemia-reperfusion; manganese(III) tetrakis(1-methyl-4-pyridyl)porphyrin; reactive oxygen species

Reactive oxygen species (ROS) contribute significantly to apoptosis in renal ischemia-reperfusion (IR) injury, however the exact mechanisms are not well understood. We used novel lentiviral vectors to over-express superoxide dismutase 1 (SOD1) in proximal tubular epithelial (LLC-PK1) cells and determined effects of SOD1 following ATP depletion-recovery, used as a model to simulate renal IR. SOD1 over-expression partially protected against cytotoxicity (P < 0.001) and decreased superoxide (O2•−) in ATP depleted cells. The ATP depletion-mediated increase in nuclear fragmentation, an index of apoptosis and activation of caspase-3 was also partially blocked by SOD1 (P < 0.05). However, SOD1 over-expression was insufficient to completely attenuate caspase-3, indicating that ROS other than cytoplasmic O2•− are involved in ATP depletion mediated injury. To test the contribution of hydrogen peroxide, a subset of enhanced green fluorescent protein (EGFP) and SOD1 (serum free and injured) cells were treated with polyethylene glycol-catalase (PEG-catalase). As expected there was 50% reduction in cytotoxicity and caspase-3 in SOD1 cells compared to EGFP cells; catalase treatment decreased both indices by an additional 28% following ATP depletion. To test the role of mitochondrial derived superoxide, we also treated a subset of LLC-PK1 cells with the mitochondrial antioxidant, Mito- TEMPO. Treatment with MitoTEMPO also decreased ATP depletion induced cytotoxicity in LLC-PK1 cells in a dose dependant manner. These studies indicate that both SOD1 dependent and independent pathways are integral in protection against ATP depletion-recovery mediated cytotoxicity and apoptosis, however more studies are needed to delineate the signaling mechanisms involved.

Background-Improved kidney preservation methods are needed to reduce ischemiareperfusion (IR) injury in kidney allografts. Lifor is an artificial preservation solution comprised of nutrients, growth factors, and a non-protein oxygen and nutrient carrier. The current study compared the effectiveness of Lifor to University of Wisconsin solution (UW) in protecting rat kidneys from warm IR and cold storage injury.

Ten hypercalcaemic members from three generations of a family with familial hypocalciuric hypercalcaemia (FHH) were compared with age and sex matched healthy subjects. Two of the former had undergone unsuccessful subtotal parathyroidectomy. Our results showed that the hypercalcaemia was mainly attributable to an increased capacity for tubular reabsorption of calcium, but in part also to an increased release of calcium from bone. The relative hypermagnesaemia had a similar dual origin. The serum phosphate concentration was low and this could be accounted for in full by a decrease in renal tubular reabsorption of phosphate, as assessed by the renal threshold phosphate concentration (TmPO4/GFR). The results of PHT measurements with two radioimmunoassays were equivocal. Most patients had normal serum PTH values, but with one assay mean serum PTH was significantly higher in the hypercalcaemic group. We conclude that the abnormalities of the divalent cation and phosphate metabolism cannot be accounted for in full by increased circulating PTH activity, and are predominantly due to an intrinsic renal abnormality.

These results show that MnTMPyP is partially effective in reducing inflammation associated with renal IR and that reactive oxygen species play a role in modulating both pro- and anti-inflammatory pathways in acute kidney injury.