Prevention of renal injury after induction of ozone tolerance in rats submitted to warm ischaemia

ON the basis that ozone (O-3) can upregulate cellular antioxidant enzymes, a morphological, biochemical and functional renal study was performed in ra ts undergoing a prolonged treatment with O-3 before renal ischaemia, Rats w ere divided into four groups: (1) control, a medial abdominal incision was performed to expose the kidneys; (2) ischaemia, in animals undergoing a bil ateral renal ischaemia (30 min), with subsequent reperfusion (3 h); (3) O-3 + ischaemia, as group 2, but with previous treatment with O-3 (0.5 mg/kg p er day given in 2.5 ml O-2) via rectal administration for 15 treatments; (4 ) O-2 + ischaemia, as group 3, but using oxygen (O-2) alone. Biochemical pa rameters as fructosamine level, phospholipase A, and superoxide dismutases (SOD) activities, as well as renal plasma flow (RPF) and glomerular filtrat ion rate (GFR), were measured by means of plasma clearance of p-amino-hippu rate and inulin, respectively. In comparison with groups 1 and 3, the RPF a nd GFR were significantly decreased in groups 2 and 4, Interestingly, renal homogenates of the latter groups yielded significantly higher values of ph ospholipase A activity and fructosamine level in comparison with either the control (1) and the O-3 (3) treated groups. Moreover renal SOD activity sh owed a significant increase in group 3 without significant differences amon g groups 1, 2 and 4, Morphological alterations of the kidney were present i n 100%, 88% and 30% of the animals in groups 2, 4 and 3, respectively, It i s proposed that the O-3 protective effect can be ascribed to the substantia l possibility of upregulating the antioxidant defence system capable of cou nteracting the damaging effect of ischaemia, These findings suggest that, w henever possible, ozone preconditioning may represent a prophylactic approa ch for minimizing renal damage before transplantation.