Effect of Nitrendipine on Blood Pressure, Plasma Renin, and Exchangeable Sodium in DOC-Salt Hypertension in the Rat

Abstract

Desoxycorticosterone-salt (DOC-salt) hypertension in the rat can be prevented by administration of nitrendipine. We have studied the effect of nitrendipine on exchangeable body sodium (NaE) in this model. Eighteen male Sprague-Dawley rats had a left nephrectomy and after 14 days received subcutaneous injections of deoxycorticosterone (Percorten, CIBA) 12.5 mg three times weekly for 4 weeks and were given 22Na-labeled 1% saline plus 0.2% KCl to drink. They were fed a sodium-free diet. NaE, systolic blood pressure, and body weight were measured weekly. The animals were divided into two groups of nine, one group being given subcutaneous nitrendipine 5 mg/kg twice daily, while the control group was given vehicle only. Blood samples from conscious animals were drawn at the start and at the end of the study for measurement of plasma renin concentration (PRC) and haematocrit, and at the end for atrial natriuretic peptide (ANP) measurement. Twenty-four hour urine was collected at the end of the study from eight rats of each group, and urine and blood samples were taken for biochemical analysis. In the control rats, blood pressure rose from an initial mean of 140.6 +/- 1.7 (SEM) mm Hg to 187.2 +/- 6.5 (p less than 0.001) at week 4. In the nitrendipine-treated rats, blood pressure fell from 143.9 +/- 2 at week 0 to 127.2 +/- 3.3 mm Hg at week 4 (p less than 0.001). However, body weight rose similarly in both groups and there was no difference in NaE between the groups throughout the study.(ABSTRACT TRUNCATED AT 250 WORDS)