This study was carried out to investigate the action of adenosine triphosphate (ATP) on the motility of immature pig uterine smooth muscle. ATP appeared contractile responses in a dose-dependent manner, showing the maximal contraction at the concentration of 10-3M in the uterine smooth muscle strip. The contractile responses by ATP(10-4M) were not affected by atropine (10-6M), phentolamine (10-6M), propranolol (10-6M), pyrilamine (10-6M), cimetidine (10-6M), and theophyulline (5 X 10-5M), but were inhibited uncompetitively by quinidine. The effects of these drugs on the contractile responses by prostaglandin F2α(PGF2α) were also comparable to those observed with ATP. When muscle strips were pretreated with indomethacin (5 X 10-5M) for 20 min., the contractile responses by ATP(10-4M) were completely inhibited. But the contractile responses by PGF2α were not affected by indomethacin. These results suggest that ATP elicited the contraction through noncholinergic- and nonadrenergic-receptor mediated by prostaglandin F2α in pig uterine smooth muscle.
