Effect of propranolol of vascular responses to sympathetic nerve stimulation and plasma renin activity in mongrel dogs.

I.v administration of propranolol (0.2 mg/kg and 1.0 mg/kg) to pentobarbital-anesthetized dogs produced blockade of cardiac beta-receptors and a significant decrease in heart rate. However, only the higher dose of propranolol demonstrated a significant hypotensive effect. Furthermore, this hypotensive action of propranolol was not associated with either adrenergic neruron blockade or changes in plasma renin activity. These results indicate that the initial hypotensive action of propranolol in mongrel dogs is not due to the blockade of beta-receptors, alterations in peripheral sympathetic nervous transmission or plasma renin activity. On the other hand, the action that propranolol is reported to have within the central system may play an important role in accounting for the acute blood pressure lowering action of the compound in mongrel dogs.