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PHARMACOLOGICAL CHARACTERIZATION OF THE EXCITATORY INNERVATION TO THE GUINEA‐PIG URINARY BLADDER in vitro: EVIDENCE FOR BOTH CHOLINERGIC AND NON‐ADRENERGIC‐NON‐CHOLINERGIC NEUROTRANSMISSION
Author(s) -
KRELL ROBERT D.,
McCOY JEAN L.,
RIDLEY PETER T.
Publication year - 1981
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.1476-5381.1981.tb09950.x
Subject(s) - guanethidine , hexamethonium , phentolamine , cholinergic , tetrodotoxin , endocrinology , medicine , atropine , excitatory postsynaptic potential , stimulation , bethanechol , inhibitory postsynaptic potential , prazosin , chemistry , adrenergic , biology , muscarinic acetylcholine receptor , antagonist , receptor
1 Field stimulation of strips of guinea‐pig isolated urinary bladder with 5 s trains at 0.1 to 15 H z resulted in frequency‐dependent, reproducible contractions. 2 At concentrations of 1 and 4× 10 −7 M and 1 × 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 × 10 −7 M, inhibited contractions at all frequencies by 80 to 90%. 4 Physostigmine, 2 × 10 −6 M, significantly enhanced the contractile response to frequencies of less than 10 H z but did not enhance responses resistant to inhibition by atropine. Hexamethonium, 1 × 10 −4 M, slightly enhanced the contractile response to frequencies of 4 H z or greater. 5 (±)‐Propranolol (5 × 10 −6 m), guanethidine (1 × 10 −6 m), phentolamine (5 × 10 −6 m) and clonidine (3 × 10 −8 m) each enhanced the contractile response to field stimulation. 6 Contractile responses obtained in the presence of atropine (4×10 −7 m) and guanethidine (1 × 10 −6 M) increased with time and were inhibited 60 to 80% by TTX (5 × 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.