Susceptibility to Experimental Pyelonephritis When Hormonal Hypertension Is Prevented by Hypotensive Drugs *

Abstract

Rats with desoxycorticosterone (DCA) -saline induced hypertension have been shown to exhibit increased susceptibility to experimental pyelonephritis (1, 2). These studies lend support to the hypothesis that various injuries, including nephrosclerosis, predispose to human pyelonephritis and that pyelonephritis is superimposed upon hypertensive disease more frequently than is usually suspected. Others (3-5) have shown that reserpine and/or hydralazine, when given to rats with DCA-saline hypertension, will reduce blood pressure, delay or prevent renal and vascular pathological changes, and increase the average survival time. Masson, McCormack, Dustan and Corcoran (6) demonstrated a close association between blood pressure levels and the presence and character of the vascular lesions in rats with hydralazine-treated renal hypertension. The previously demonstrated susceptibility of rats with DCA-saline hypertension might have been due either to an effect of the hypertension and vascular disease or to some other effect of the administered steroid and saline. The present investigation was therefore designed to separate these possibilities. MATERIALS AND METHODSWhite, female Sprague-Dawley strain rats, weighing 100 to 150 g, were used. The experimental animals of Groups A and B were subjected to left nephrectomy and 3 fortnightly injections of a long-acting derivative of DCA 1 in 25 mg doses. Drinking water contained 1 per cent NaCl and 0.49 per cent KCI. The latter had been previously found (1) to prevent potassium depletion which otherwise results from the DCA-saline regimen.In addition, 40 mg of hydralazine' was added to each liter of the drinking solution of Group A animals and they received 1 mg per kg (later reduced to 0.5 mg per