title: Adenosine 5'-triphosphate release evoked by electrical nerve stimulation from the guinea-pig gallbladder.
abstract: The endogenous release of adenosine 5'-triphosphate (ATP) from strips of guinea-pig gallbladder during transmural stimulation (TS) was measured with a firefly luciferine-luciferase reaction. TS (15V, 1 ms, 0.5-5 Hz, for 1 min) caused a rapid and marked increase of ATP release in a frequency-dependent manner. Both ATP release and contractions evoked by TS (15 V, 5 Hz, 1 ms) were completely abolished in Ca-free medium. BaCl2 (3 X 10(-3) M), a direct muscle stimulant, produced almost the same degree of contractile tension as TS (15 V, 5 Hz, 1 ms) while the ATP release induced by BaCl2 was significantly reduced to about 60 percent of that induced by TS. Atropine (10(-6) M) significantly reduced TS-evoked contraction without affecting ATP release. It was suggested, therefore, that some of the ATP release induced by TS was of neural origin. Theophylline (a P1-purinoreceptor antagonist) 10(-6) M, quinidine (a non-specific P2-purinoreceptor antagonist) 10(-6) M and apamin (a potassium channel blocking agent) 10(-8) M had no effects on TS-evoked contraction and ATP release, suggesting the absence of a presynaptic autoregulatory mechanism of ATP release in the guinea-pig gallbladder.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001464:Barium / Q000494:pharmacology; D017609:Barium Compounds; D002712:Chlorides; D004558:Electric Stimulation; D005260:Female; D005704:Gallbladder / Q000187:drug effects / Q000378:metabolism; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000378:metabolism* / Q000502:physiology; D013806:Theophylline / Q000494:pharmacology
chemical_list: D017609:Barium Compounds; D002712:Chlorides; C024986:barium chloride; D001464:Barium; D000255:Adenosine Triphosphate; D013806:Theophylline