[abstract] HBO IMPROVES OXIDANT/ANTIOXIDANT BALANCE IN ISCHEMIC KIDNEY IN RATS A POSSIBE MECHANISM FOR ENHACEMENT OF RENAL FUNCTION IN ACUTE RENAL FAILURE

Abstract

BACKGROUND: Hypoperfusion to the kidney often leads to renal dysfunction which might culminate in acute renal failure (ARF), a frequent threatening complication following severe trauma. In previous study we have shown that HBO attenuated the decline in glomerular filtration rate (GFR), following unilateral renal ischemia in rats. Oxidative stress is a major cause of free radical formation, contributing to cell damage in renal ischemia. However the effect of HBO on oxidant/antioxidant balance is controversial. Therefore the aim of our study was to explore the potential mechanisms by which HBO protects renal function in a model of acute renal ischemia in ratMATERIALS AND METHODS: To clarify the effect of HBO on the ischemic kidney, we examined the levels of 4-hydroxy-2-noneal (4-HNE), a marker of lipid peroxidation in tissues, and those of the antioxidant superoxide dismutase (Cu/Zn-SOD). After unilateral renal artery clamping (45 minutes followed by reperfusion), rats were treated by HBO, (2 treatments of 100percent oxygen at 2.5 absolute atmospheres for 90 min each, in 24 hours). Two days following ischemia, rats were killed and both kidneys (control and ischemic) were prepared for immunohistochemical examination. Immunostaining was performed with antibodies against 4-HNE and Cu/Zn-SOD, and the stained areas were analyzedRESULTS: 4-HNE was found mainly in the outer medulla of the ischemic kidney. The staining area was significantly decreased in the HBO treated group: 12.7percent+/-0.84 vs. 53.1percent+/-1.55 (pless than0.001). Staining area of Cu/Zn-SOD in the medulla of normal kidney was very small compared to untreated ischemic kidney (1.17percent+/-0.1 vs.10.2percent+/-0.8). But, it was significantly increased in the HBO treated ischemic kidney (17.3percent+/-1.1, pless than0.001)CONCLUSIONS: The reduced 4HNE and increased Cu/Zn-SOD suggests an improvement in oxidant/antioxidant balance following HBO treatment. This mechanism may contribute to the protective role of HBO against cell damage, and explain in part the improvement in renal function following renal ischemia.