EFFECTS OF AUTONOMIC DRUGS ON DEVELOPMENT OF TENSION INDUCED BY POTASSIUM IN ISOLATED NORMAL HUMAN UTERINE MUSCLES AND UTERINE LEIOMYOMATA

¹ Departments of Pharmacology and Pathology, Albany Medical College, Albany, New York

The response of leiomyomata of human uteri to autonomic drugs and to excess potassium has been shown to differ from that of normal uterine muscle. The failure to demonstrate a normal stimulatory effect of acetylcholine and potassium could be traced to a relative lack of labile calcium because incubation of leiomyomata in Ringer-Locke solution containing excess calcium leads to a near-normal stimulatory response to both agents. This result is interpreted to support the claim for the dominant role of calcium in the mechanism of action of some autonomic drugs on smooth muscle.

The stimulatory effect of potassium on normal muscles could be antagonized effectively by norepinephrine and by DMPP which acted through the release of endogenous norepinephrine. An equimolar quantity of isoproterenol had no effect on the usual stimulatory response to excess potassium. The presence of acetylcholine in the muscle bath resulted in an augmentation of response to excess potassium. Therefore, the two acted summatively at several concentrations of potassium.