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EFFECTS OF HARMINE ON TRANSMEMBRANE POTENTIALS OF GUINEA‐PIG ATRIAL MUSCLE
Author(s) -
CARPENTIER ROBERT G.
Publication year - 1980
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.1476-5381.1980.tb07904.x
Subject(s) - harmaline , harmine , chemistry , guinea pig , electrophysiology , membrane potential , pharmacology , biophysics , resting potential , medicine , endocrinology , biochemistry , biology
1 The effects of harmine 8.3 × 10 −5 m on membrane potentials of guinea‐pig atrial muscle were analyzed and compared with those of harmaline. Transmembrane potentials of contractile fibres were measured during exposure to the drug at 30°C. 2 In preparations superfused with 5.4 mmol K + ‐Tyrode, harmine produced a progressive reduction in the amplitude of the action potential (AP), in the absence of any change in resting potential (RP) and a prolongation of the duration of the action potential (APD). 3 Harmaline produced an enhancement of AP; RP was not affected and APD was prolonged. 4 The amplitude of slow responses elicited by noradrenaline in 16.2 mmol K + ‐Tyrode was enhanced by harmine. 5 It is proposed that dehydrogenation of harmaline to harmine reverses the initial stimulatory action of harmaline on AP because the depressant action on the fast component of the upstroke prevails over the stimulatory effect on the slow component.