[Action of adenosine 5'-triphosphate and effects of various purinergic receptor blocking agents on the movements of an isolated guinea pig gallbladder].

Exogenously applied adenosine 5'-triphosphate (ATP) caused a biphasic response; a quick relaxation followed by a slow contraction. This response was not affected by atropine, phentolamine, propranolol and tetrodotoxin. Theophylline, quinidine and IBMX reduced ATP-induced contraction and had no effect on ATP-induced relaxation. On the other hand, apamin reduced ATP-induced relaxation and had no effect on ATP-induced contraction. Indomethacin remarkedly reduced ATP-induced contraction without affecting the relaxation. It was suggested that there were two types of receptors (apamin sensitive and apamin resistant) in the guinea-pig gallbladder.