Comparative effects of propranolol and nadolol on renal blood flow in normal rats and rats with congestive heart failure.

Mean arterial blood pressure (MAP), heart rate (HR), renal blood flow (RBF), and renal vascular resistance (RVR) were determined before and during an infusion of propranolol (18 mg/kg/hr) or nadolol (30 mg/kg/hr) in anesthetized Munich-Wistar rats with normal cardiac function. Eight rats treated with propranolol had significant reductions in MAP (110 to 98 mm Hg; p less than 0.05) and HR (316 to 242 bpm; p less than 0.01), accompanied by a 24% decrease in RBF (5.9 to 4.5 ml/min; p less than 0.05) and a 22% increase in RVR (19.4 to 23.7 mm Hg/ml/min; p less than 0.05). Although nadolol also reduced MAP (104 to 93 mm Hg; p less than 0.01) and HR (315 to 268 bpm; p less than 0.05) in eight other rats, RBF and RVR remained unchanged from baseline levels. Thus, despite similar decrements in MAP and HR, propranolol decreased renal perfusion, whereas nadolol maintained it in animals with noninfarcted myocardium. These parameters were also evaluated in rats with congestive heart failure induced by myocardial infarction at least 3 weeks prior to their receiving either propranolol (18 mg/kg/hr; n = 6) or nadolol (30 mg/kg/hr; n = 6). In the basal state, rats with congestive heart failure had significantly (p less than 0.05) lower MAP, HR, and RBF and higher (p less than 0.01) RVR compared with control rats. Propranolol and nadolol induced comparable falls (p less than 0.05) in MAP and HR. Whereas RBF tended to fall with propranolol (3.3 to 2.4 ml/min), renal perfusion was well maintained with nadolol (3.4 to 3.8 ml/min).(ABSTRACT TRUNCATED AT 250 WORDS)