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RELAXATION OF GUINEA‐PIG FUNDIC STRIP BY ADENOSINE, ADENOSINE TRIPHOSPHATE AND ELECTRICAL STIMULATION: LACK OF ANTAGONISM BY THEOPHYLLINE OR ATP TREATMENT
Author(s) -
BAER HANS P.,
FREW ROBERT
Publication year - 1979
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.1476-5381.1979.tb08679.x
Subject(s) - theophylline , adenosine , stimulation , inhibitory postsynaptic potential , medicine , endocrinology , adenosine triphosphate , adrenergic , chemistry , adenosine receptor , biology , receptor , agonist
1 Theophylline relaxed isolated strips of guinea‐pig stomach fundus in a dose‐dependent manner; above 50 to 100 μ m responses showed no fade for up to 90 min. 2 Relaxant responses to adenosine, adenosine triphosphate (ATP), noradrenaline, and to electric field stimulation of non‐adrenergic inhibitory nerves were not affected in a significant manner in the presence of 50 μ m theophylline. 3 In tissues which showed complete fade of initial responses in the continued presence of 50 μ m ATP, the effects of stimulation of non‐adrenergic inhibitory nerves remained unaltered, suggesting that the ATP receptor has no function in non‐adrenergic inhibitory transmission in this tissue. 4 These findings are opposite to those of Okwuasaba, Hamilton & Cook (1977), who claimed that 50 μ m theophylline almost fully inhibited relaxation induced by adenosine, ATP and nerve stimulation and that ATP‐induced fade also abolished sensitivity to inhibitory nerve stimulation.