Effect of captopril on the progression of induced pyelonephritis in the rat

The effect of captopril, an angiotensin-converting enzyme inhibitor, was studied in rats subjected to Escherichia coli pyelonephritis. Eight weeks after pyelonephritis was induced in male Sprague-Dawley rats, the rats were randomly assigned to treatment groups based on urinary protein excretion. In experiment 1, rats were given captopril, 50 mg/kg of body weight, or saline solution via daily intraperitoneal injection. To eliminate complications with captopril-induced peritonitis, experiment 2 was performed in which rats were given the same treatment by daily gavage. In both experiments, 24-hour urinary protein excretion in the saline-treated rats was significantly greater than that of the captopril-treated rats after 12 weeks of treatment (P less than 0.05). Plasma urea nitrogen, plasma creatinine, and endogenous creatinine clearance did not differ between treatment groups during the course of therapy in experiment 1. There were no differences in these values in experiment 2, except at week 8 of treatment when the captopril-treated rats had significantly lower plasma creatinine and higher endogenous creatinine clearance than did the saline-treated rats (P less than 0.05). There was also no difference between treatment groups in the degree of morphologic renal damage based on light microscopic evaluation of kidneys at the end of treatment.