Relaxant Effect of ATP on the Mechanical Activity of the Cat Small Intestine

1. Effects of ATP and its related compounds on the contractile activity of the cat small intestine were examined. 2. ATP, ADP, AMP and adenosine exhibited the relaxant effect on the mechanical activity of atropinized segments but guanin had o inhibitory effect. 3. After TTX or hexamethonium, ATP still had an infibitory effect on the contractile activity. 4. ATP showed the relaxant action in α-adrenergic blooking drugs and in procaine, but not showed the relaxant sction in quinidine. 5. The possibility on the presence of non-adrenergic inhibitory nerves and its transmitter substance was discussed.