Effects of propranolol in chronic two-kidney Goldblatt hypertension in rats

Propranolol administered subcutaneously in a dise of 30 mg/kg twice a day for 3 weeks did not significantly lower systolic tail blood pressure (STBP) in chronic two-kidney Goldblatt hypertension in rats. Plasma renin activity (PRA) measured at the end of the treatment was not significantly different in propranolol treated and dextrose treated rats, although there was marked bradycardia in propranolol treated rats. However, 3 out of 10 propranolol treated hypertensive rats had pressures in the normotensive range during the last week of therapy. PRA values in these three rats were significantly lower than those in dextrose treated hypertensive rats. STBP on day 20 showed a positive correlation with PRA in both propranolol (r = 0.90, p less than 0.01) and dextrose (r = 0.85, p less than 0.01) treated hypertensive rats. Hypertension was associated with an increase in heart weight, which was significantly blunted but not abolished by propranolol treatment. Thus, propranolol did not decrease blood pressure in most rats with chronic two-kidney Goldblatt hypertension; when it did lower blood pressure, its antihypertensive effect appeared related to its renin suppression effect. Furthermore, propranolol mitigated hypertension induced cardiac hypertrophy, independently of its antihypertensive effect.