Purinoceptor desensitization impairs but does not abolish the non-cholinergic motor transmission in rat isolated urinary bladder.
In order to determine the effectiveness of purinoceptor desensitization in blocking the non-cholinergic motor transmission in rat detrusor, isolated preparations of urinary bladder, pretreated with atropine 3 microM + indomethacin 10 microM were contracted by alpha, beta-methylene-ATP, a stable analogue of ATP and by electrical stimulation at frequencies of 1, 2, 4, 8 and 16 Hz. The mean maximum tension generated by alpha, beta-methylene-ATP was 43% of that by electrical field stimulation. Desensitization to the contractile action of alpha, beta-methylene-ATP was achieved by administration of alpha, beta-methylene-ATP 10 microM, three times at 10 min intervals. Responses to electrical field stimulation were reduced following induction of alpha, beta-methylene-ATP desensitization but a sizeable proportion of the response persisted (51% at 1 Hz; 29% at 8 Hz). Tetrodotoxin 0.5 microM abolished the responses to electrical field stimulation, persisting after alpha, beta-methylene-ATP desensitization. It is concluded that ATP is unlikely to be the sole non-cholinergic motor transmitter in the rat detrusor.
Luheshi
G
G
Department of Pharmacological Sciences, Medical School, Newcastle Upon Tyne, U.K.
Zar
A
A
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001341:Autonomic Nervous System / Q000502:physiology*; D004558:Electric Stimulation; D004566:Electrodes; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D009046:Motor Neurons / Q000187:drug effects*; D009119:Muscle Contraction / Q000187:drug effects; D051381:Rats; D011983:Receptors, Purinergic / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology; D013779:Tetrodotoxin / Q000494:pharmacology; D001743:Urinary Bladder / Q000294:innervation*
D011983:Receptors, Purinergic; D013779:Tetrodotoxin; D001285:Atropine; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D007213:Indomethacin