text: Carvedilol produced significant inhibition of the alpha 1 adrenoceptor mediated pressor response to cirazoline in the pithed rat, but had no effect on the alpha 2 adrenoceptor mediated pressor response to B-HT 933, suggesting that << carvedilol >> is also an [[ alpha 1 adrenoceptor ]] antagonist at antihypertensive doses.