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THE INHIBITORY RESPONSE OF THE RABBIT ANOCOCCYGEUS MUSCLE
Author(s) -
Wai San San,
Coupar I. M.
Publication year - 1976
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1976.tb00598.x
Subject(s) - acetylcholine , hexamethonium , stimulation , tetrodotoxin , chemistry , endocrinology , inhibitory postsynaptic potential , medicine , phenylephrine , atropine , tetraethylammonium , nicotinic agonist , acetylcholine receptor , biology , receptor , potassium , organic chemistry , blood pressure
SUMMARY 1. Strips of rabbit anococcygeus muscle were submaximally contracted by the addition of phenylephrine to the bath fluid. 2. Acetylcholine, dimethylphenylpiperazinium and electrical field stimulation caused relaxation. Relaxation induced by acetylcholine and field stimulation was blocked by tetrodotoxin but only the acetylcholine‐induced response was inhibited by lignocaine, tetraethylammonium and hexamethonium. The responses to both acetylcholine and field stimulation were resistant to atropine, practolol, and sotalol. 3. Relatively high concentrations of ATP caused relaxation. 4. Histological investigation did not show any cells resembling autonomic ganglion cells. 5. It is suggested that both acetylcholine and field stimulation release an inhibitory transmitter from nerve endings and that the release by acetylcholine is mediated through nicotinic receptor stimulation.