Effects of Adenosine Triphosphate and Its Related Compounds on the Phasic Contraction of the Guinea-pig Vas Deferens and Ureter Smooth Muscle

1. The effects of ATP and its related nucleotides on the phasic contraction of vas deferens and ureter smooth muscle were examined. 2. ATP and related compounds increased the tension of phasic contraction in vas deferens while inhibited in ureter. 3. The potentiatory and inhibitory action of ATP was observed in tetrodotoxin. ATP potentiated the spontaneous mechanical activity of vas deferens prosuced by Ba++. 4. Quinidine prevented the effects of ATP on both preparations and cysteine changed the effects of ATP and ADP. 5. It is concluded that extracellularly applied ATP and its related nucleotides act to smooth muscle directly. Quinidine prevents the ATP action at the cell membrane.