Effect of urapidil on β-adrenoceptors of rat atria

Abstract

The effects of the antihypertensive drug urapidil were studied on chronotropic responses to isoprenaline in rat isolated atria. Urapidil (1-30 μM) antagonized the responses to isoprenaline competitively, and the pA2 value was 6.05. Thus, in addition to its α1-adrenoceptor blocking action for which the pA2 value is about 7, urapidil has β-adrenoceptor blocking activity. © 1985.