Abstract
The present study was undertaken to compare the antihypertensive effects of β-blocking agents and to clarify the relations between antihypertensive effects and β-blocking actions. In this study, blood pressure was measured by a direct cannulation of the abdominal aorta. Subcutaneous administration of carteolol and pindolol caused a significant fall in mean blood pressure in both normotensive and spontaneously hypertensive rats, whereas propranolol produced a rise in blood pressure. Maximum fall in blood pressure was observed 3 ?? 7 hr after the administration of carteolol and pindolol. In order to determine the β-blocking action, changes in heart rate and blood pressure in response to isoproterenol (3 μg/kg i.v.) were observed during the experiment. β-Blocking action was found as early as 1 hr after subcutaneous administration. Carteolol showed the most effective blocking action throughout the experiment. Although β-blocking agents lowered the blood pressure in this experiment, there was no apparent parallel between antihypertensive effects and β-blocking action on the cardiac function.
