[Lipid peroxidation in a kidney tissue homogenate from rats under heat-induced ischemia with and without glucocorticoid protection].

Lipid peroxidation (LPO) was investigated in cortical layer homogenates from 56 rat kidneys, intact or exposed to a 30-minute heat ischemia performed without any protection or after a preliminary administration of prednisolone alone or in combination with methypred. Prednisolone was administered i.m. in a dose of 30 mg/kg 2 hrs before and the same dosage of methypred a day before the onset of the experiment. Homogenates were studied both for the initial levels of malonic dialdehyde (MDA) and for the MDA formation in the presence of LPO which was activated in the phosphate buffer by pH 6.8 ascorbate (5.10(-4) M) 5, 10, 15, 20, 25 and 30 minutes after the incubation. The results obtained demonstrated that versus the intact kidneys, in the kidneys exposed to a 30-minute treatment with heat ischemia there were increased levels of initial MDA in the renal tissue, a dramatic increment of its formation during the incubation of homogenate with ascorbate. Shifts in the kinetic curves in homogenates from ischemic kidneys were noted as well. A more dramatic rise (versus intact kidneys) in the MDA formation levels in the presence of LPO observed at the initial stage of the incubation was suggestive of an exhaustive effect of heat ischemia on the system of endogenous antioxidants. The dramatic increment of MDA levels was recorded during a 30-minute incubation. Administration of prednisolone alone or in combination with methypred resulted in a significant inhibition of LPO in ischemic renal tissue.(ABSTRACT TRUNCATED AT 250 WORDS)