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THE EFFECTS OF 4‐AMINOPYRIDINE ON THE ISOLATED VAS DEFERENS AND ITS EFFECTS ON THE INHIBITORY PROPERTIES OF ADENOSINE, MORPHINE, NORADRENALINE AND γ‐AMINOBUTYRIC ACID
Author(s) -
STONE T.W.
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.tb16817.x
Subject(s) - adenosine , vas deferens , chemistry , phentolamine , inhibitory postsynaptic potential , 4 aminopyridine , morphine , pharmacology , tetraethylammonium , medicine , endocrinology , potassium channel , biochemistry , biology , potassium , receptor , organic chemistry
1 Adenosine, adenosine 5′‐triphosphate (ATP), morphine, noradrenaline, γ‐aminobutyric acid (GABA) phentolamine and amyl nitrite were used to inhibit electrically‐evoked contractions of the isolated superfused vas deferens of the mouse. 2 The inhibitory effects of adenosine ATP, morphine, noradrenaline and GABA, which are thought to be due to presynaptic action, were reduced by perfusion with media containing 4‐aminopyridine (4AP) or tetraethylaminonium (TEA) ions. The inhibitory effects of phentolamine and amyl nitrite were unaffected by 4AP or TEA. 3 Quinidine, which like 4AP and TEA produced some increase of twitch height, did not reduce responses to the various agonists, indicating that an increased muscle contraction was not itself responsible for the reduced responses. 4 It is concluded that antagonism between 4AP and adenosine is not a specific interaction, as had been suggested, but probably reflects an interaction with Ca 2+ requiring processes in the presynaptic terminal.