Contraction of the @entity35 detrusor muscle is mediated by cholinergic and purinergic mechanisms. The present study was carried out to look at the influence of cromakalim, compared with @entity3897 , @entity5747 and @entity594 on the contractile response evoked by single shock and exogenous agonists ( @entity5402 and @entity855 ) in @entity35 urinary bladder. Cromakalim was able to inhibit only partially the response to @entity5402 and profoundly affected the response to exogenous @entity855 . @entity3897 suppressed the response to @entity5402 and was inactive versus @entity855 . @entity5747 was inactive versus @entity5402 and was able to antagonize the response to @entity855 . @entity594 proved to be a non-competitive antagonist versus @entity5402 (pD2 = 7.66 +/- 0.05) and deeply affected the response to @entity855 . Cromakalim inhibited only partially the first, purinergic, phase of the electrically evoked response but was able to inhibit in a concentration-dependent manner the second, cholinergic, phase (logIC50 = 6.87 +/- 0.05). @entity594 blocked both the phases. @entity3897 blocked partially only the second phase. @entity5747 inhibited the first phase but, at least partially, also the second one. The combination of @entity3897 and @entity5747 enhanced the inhibition of the second phase. The antagonistic effect of @entity5747 on the second phase could indicate an overlap of the purinergic and cholinergic components. The comparison between pre- and postjunctional effects indicates that cromakalim acts on purinergic transmission predominantly postjunctionally. On the contrary, the action on cholinergic transmission seems to occur mainly at prejunctional level. This conclusion can be relevant in view of the claimed importance of K+ channel openers in the treatment of @entity1494 .

Effect of cromakalim on the purinergic and cholinergic transmission in the XXXX detrusor muscle.

@entity1494 :: ('MESH:D001745', 'Disease') :: ['urinary disorders'] @entity3897 :: ('MESH:D001285', 'Chemical') :: ['Atropine', 'atropine'] @entity594 :: ('MESH:D009543', 'Chemical') :: ['nifedipine', 'Nifedipine'] @entity35 :: ('10116', 'Species') :: ['rat'] @entity5747 :: ('MESH:D013498', 'Chemical') :: ['suramin', 'Suramin'] @entity5402 :: ('MESH:D002217', 'Chemical') :: ['carbachol'] @entity855 :: ('MESH:D000255', 'Chemical') :: ['ATP']
@entity35 :: (10116,Species) :: ['rat']
