Carey B, Whalley E T
Br J Pharmacol. 1979 Sep;67(1):13-5.
Isoprenaline produced dose-dependent reductions of responses of the isolated uterus of the rat produced by an EC(80) of acetylcholine. Propranolol acted as a competitive antagonist to isoprenaline. Labetolol also reduced the acetylcholine-induced contractions but was much less potent than isoprenaline. The greatest reduction was smaller than that produced by isoprenaline. Propranolol antagonized the lower doses of labetolol. It is suggested that labetolol possesses partial agonist activity at the beta-adrenoceptors of the rat isolated uterus.
异丙肾上腺素能使乙酰胆碱的EC(80)所引起的大鼠离体子宫反应呈剂量依赖性降低。普萘洛尔对异丙肾上腺素起竞争性拮抗作用。拉贝洛尔也能降低乙酰胆碱诱导的收缩，但效力远低于异丙肾上腺素。其最大降低幅度小于异丙肾上腺素所产生的降低幅度。普萘洛尔能拮抗较低剂量的拉贝洛尔。提示拉贝洛尔在大鼠离体子宫的β肾上腺素受体上具有部分激动剂活性。
