Effect of chronic treatment with propranolol on blood pressure and cardiovascular reactivity in spontaneously hypertensive rats.

Young SHR were treated with propranolol (16 or 64 mg/kg per day) from 6 up to 14 weeks of age. Systolic blood pressure was significantly lower in SHR treated with propranolol (64 mg/kg) than in untreated SHR; no effect was seen in SHR treated with 16 mg/kg. The hemodynamic characteristics of the hindquarter vascular beds did not significantly differ between untreated and propranolol-treated SHR. Adult SHR were given propranolol (64 mg/kg per day) from 5 up to 8 months of age. Moderate reduction of systolic blood pressure was observed from 2 to 3 months of propranolol treatment. The cardiovascular pressor response to noradrenaline decreased in propranolol-treated SHR, while the decreased responsiveness was not found after pithing.