On the basis that ozone (O3) can upregulate cellular antioxidant enzymes, a morphological, biochemical and functional renal study was performed in rats undergoing a prolonged treatment with O3 before renal ischaemia. Rats were divided into four groups: (1) control, a medial abdominal incision was performed to expose the kidneys; (2) ischaemia, in animals undergoing a bilateral renal ischaemia (30 min), with subsequent reperfusion (3 h); (3) O3 + ischaemia, as group 2, but with previous treatment with O3 (0.5 mg/kg per day given in 2.5 ml O2) via rectal administration for 15 treatments; (4) O2 + ischaemia, as group 3, but using oxygen (O2) alone. Biochemical parameters as fructosamine level, phospholipase A, and superoxide dismutases (SOD) activities, as well as renal plasma flow (RPF) and glomerular filtration rate (GFR), were measured by means of plasma clearance of p-amino-hippurate and inulin, respectively. In comparison with groups 1 and 3, the RPF and GFR were significantly decreased in groups 2 and 4. Interestingly, renal homogenates of the latter groups yielded significantly higher values of phospholipase A activity and fructosamine level in comparison with either the control (1) and the O3 (3) treated groups. Moreover renal SOD activity showed a significant increase in group 3 without significant differences among groups 1, 2 and 4. Morphological alterations of the kidney were present in 100%, 88% and 30% of the animals in groups 2, 4 and 3, respectively. It is proposed that the O3 protective effect can be ascribed to the substantial possibility of upregulating the antioxidant defence system capable of counteracting the damaging effect of ischaemia. These findings suggest that, whenever possible, ozone preconditioning may represent a prophylactic approach for minimizing renal damage before transplantation.

Chronic renal failure (CRF) represents a world health problem. Ozone increases the endogenous antioxidant defense system, preserving the cell redox state. The aim of this study is to evaluate the effect of ozone/oxygen mixture in the renal function, morphology, and biochemical parameters, in an experimental model of CRF (subtotal nephrectomy). Ozone/oxygen mixture was applied daily, by rectal insufflation (0.5 mg/kg) for 15 sessions after the nephrectomy. Renal function was evaluated, as well as different biochemical parameters, at the beginning and at the end of the study (10 weeks). Renal plasmatic flow (RPF), glomerular filtration rate (GFR), the urine excretion index, and the sodium and potassium excretions (as a measurement of tubular function) in the ozone group were similar to those in Sham group. Nevertheless, nephrectomized rats without ozone (positive control group) showed the lowest RPF, GFR, and urine excretion figures, as well as tubular function. Animals treated with ozone showed systolic arterial pressure (SAP) figures lower than those in the positive control group, but higher values compared to Sham group. Serum creatinine values and protein excretion in 24 hours in the ozone group were decreased compared with nephrectomized rats, but were still higher than normal values. Histological study demonstrated that animals treated with ozone showed less number of lesions in comparison with nephrectomized rats. Thiobarbituric acid reactive substances were significantly increased in nephrectomized and ozone-treated nephrectomized rats in comparison with Sham group. In the positive control group, superoxide dismutase (SOD) and catalase (CAT) showed the lowest figures in comparison with the other groups. However, ozone/oxygen mixture induced a significant stimulation in the enzymatic activity of CAT, SOD, and glutathione peroxidase, as well as reduced glutathione in relation with Sham and positive control groups. In this animal model of CRF, ozone rectal administrations produced a delay in the advance of the disease, protecting the kidneys against vascular, hemorheological, and oxidative mechanisms. This behavior suggests ozone therapy has a protective effect on renal tissue by downregulation of the oxidative stress shown in CRF.

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