Pharmacological characterization of the excitatory innervation to the guinea-pig urinary bladder in vitro: evidence for both cholinergic and non-adrenergic-non-cholinergic neurotransmission.
1 Field stimulation of strips of guinea-pig isolated urinary bladder with 5 s trains at 0.1 to 15 Hz resulted in frequency-dependent, reproducible contractions. 2 At concentrations of 1 and 4 x 10(-7) M and 1 x 10(-6) M, atropine produced a variable, partial inhibition of contractions at all frequencies but was most effective at frequencies of 3 Hz or more. 3 Tetrodotoxin (TTX), 5 x 10(-7) M, inhibited contractions at all frequencies by 80 to 90%. 4 Physostigmine, 2 x 10(-6) M, significantly enhanced the contractile response to frequencies of less than 10 Hz but did not enhance responses resistant to inhibition by atropine. Hexamethonium, 1 x 10(-4) M, slightly enhanced the contractile response to frequencies of 4 Hz or greater. 5 (+/-)-Propranolol (5 x 10(-6)M), guanethidine (1 x 10(-6)M), phentolamine (5 x 10(-6)M) and clonidine (3 x 10(-8)M) each enhanced the contractile response to field stimulation. 6 Contractile responses obtained in the presence of atropine (4 x 10(-7) M) and guanethidine (1 x 10(-6) M) increased with time and were inhibited 60 to 80% by TTX (5 x 10(-7)M. 7 It is concluded that the cholinergic nervous system contributes, in part, to electrically-induced excitatory contractions of the isolated urinary bladder of the guinea-pig. Concomitant sympathetic stimulation appears to serve an inhibitory role. In addition, a major portion of the contractile response appears to be due to a non-cholinergic non-adrenergic, as yet unidentified, substance.
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D004347:Drug Interactions; D004558:Electric Stimulation; D006168:Guinea Pigs; D006584:Hexamethonium Compounds / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D010275:Parasympathetic Nervous System / Q000187:drug effects / Q000502:physiology*; D010830:Physostigmine / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects*; D013779:Tetrodotoxin / Q000494:pharmacology; D001743:Urinary Bladder / Q000294:innervation*
D006584:Hexamethonium Compounds; D013779:Tetrodotoxin; D001285:Atropine; D010830:Physostigmine