Atropine resistant excitation of the urinary bladder: the possibility of transmission via nerves releasing a purine nucleotide

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Abstract
1 The possibility that a purine nucleotide is involved in excitatory transmission to the urinary bladder has been tested. All the purine compounds tested which contained a pyrophosphate bond produced contraction, adenosine triphosphate (ATP) being the most potent. Adenosine and adenosine monophosphate caused relaxation. 2 The response to ATP closely mimicked the nerve-mediated contraction, both being characterized by a rapid contraction which was not maintained. A lack of sensitivity to ATP was noted in some preparations of the rat urinary bladder. 3 Both nerve-mediated contractions and contractions caused by ATP were blocked by quinidine, while the response to acetylcholine persisted. 4 Nerve-mediated responses were depressed during tachyphylaxis produced by high concentrations of ATP. Tachyphylaxis did not occur when low concentrations were used. Possible explanations for these results are discussed. 5 The results are consistent with the hypothesis that non-cholinergic excitatory nerves to the guinea-pig bladder release a purine nucleotide, but do not provide critical evidence for it.