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ATP induced‐relaxation in the mouse bladder smooth muscle
Author(s) -
Boland B.,
Himpens B.,
Paques C.,
Casteels R.,
Gillis J.M.
Publication year - 1993
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1993.tb12872.x
Subject(s) - purinergic receptor , carbachol , contraction (grammar) , adenosine triphosphate , chemistry , muscle contraction , stimulation , biophysics , muscle relaxation , medicine , detrusor muscle , endocrinology , adenosine , adenosine diphosphate , urinary bladder , biology , biochemistry , platelet , platelet aggregation
1 The effect of adenosine 5′‐triphosphate (ATP) on the free cytosolic Ca 2+ concentration ([Ca 2+ ] i ) as measured with the fluorescent Ca 2+ ‐indicator fura‐2, and on force was investigated in the intact smooth muscle strips of the mouse urinary bladder. 2 ATP elicited, when exogenously applied, a large increase of [Ca 2+ ] i with limited force development resulting in a marked Ca 2+ ‐force dissociation. 3 Release of endogenous neurotransmitters by transmural electrical stimulation (TES) for 30 s induced a steady increase of [Ca 2+ ] i and a peak contraction, followed within 15 s by a relaxation. 4 In carbachol‐prestimulated preparations, ATP elicited an initial rise of [Ca 2+ ] i followed by a return to the initial precontraction Ca 2+ ‐level. Force in contrast presented a biphasic pattern, i.e. an initial contraction was followed by a sustained relaxation. 5 In the K + ‐depolarized precontracted preparation, ATP elicited a slight initial rise of [Ca 2+ ] i . The partial relaxation of the force during depolarization was not preceded by a transient contraction. 6 The ATP‐induced relaxation of the K + ‐prestimulated preparations was not inhibited by 8‐phenyltheophylline, a potent P 1 ‐purinoceptor antagonist. 7 The order of potency for relaxation of the ATP analogues was 2‐MeSATP>ATP>βγMe‐ATP, which is characteristic for P 2y ‐purinoceptors. 8 These results indicate that, besides its activating effect, ATP also relaxes the mouse urinary bladder. It is suggested that the relaxant effect, mediated through P 2y ‐purinoceptors, is mainly responsible for the low contractile potency of ATP in the bladder.