alpha 2-Adrenoceptor agonistic effect of B-HT 920 in isolated perfused hindquarters of rats

In isolated perfused hindquarters of rats pretreated with reserpine the alpha 2-adrenoceptor selective agonist B-HT 920 decreased the flow dose-dependently. This effect was strongly antagonized by yohimbine and less by prazosin, and the reverse potency was demonstrated for methoxamine. With increasing concentrations of B-HT 920, a half maximal effect was achieved with 10(-6.64) M. This value is discussed wih respect to the antagonistic potency of B-HT 920 at alpha 1-adrenoceptors with a pA2 of 4.9.