The comparative hemodynamic effects of propranolol in chronically instrumented puppies and adult dogs.

To determine if there are age-related changes in response to propranolol, we studied the hemodynamic effects of this beta-adrenergic-blocking agent in 19 awake chronically instrumented puppies and compared the response to that of 9 awake chronically instrumented adult dogs. Following intravenous administration of 1 mg/kg propranolol, heart rate, cardiac output, stroke volume, systemic arterial mean blood pressure and systemic vascular resistance were reduced similarly in all age groups of animals, However, puppies were more sensitive to the beta-adrenergic-blocking effect of propranolol than adult dogs when stressed with isoproterenol.