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TWO ACTIONS OF γ‐AMINOBUTYRIC ACID ON THE RESPONSES OF THE ISOLATED BASILAR ARTERY FROM THE RABBIT
Author(s) -
ANWAR N.,
MASON D.F.J.
Publication year - 1982
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.1476-5381.1982.tb08770.x
Subject(s) - basilar artery , bicuculline , ed50 , stimulation , baclofen , contraction (grammar) , medicine , chemistry , endocrinology , internal carotid artery , gamma aminobutyric acid , postsynaptic potential , gabaa receptor , anesthesia , anatomy , receptor , agonist
1 In the isolated basilar artery of the rabbit, γ‐aminobutyric acid (GABA) (ED 50 ±s.e.mean, 2.4 ± 1.1 × 10 −5 m ) produced a relaxation, if the tone had been increased with 5‐hydroxytryptamine (5‐HT). 2 3‐Aminoproprane sulphonic acid (3‐APS) produced a similar, but smaller relaxation, while baclofen had no effect. The relaxation produced by GABA was inhibited by bicuculline. 3 Transmural electrical stimulation produced a reproducible contraction of the isolated basilar artery. In 9 out of 14 preparations GABA (ED 50 ± s.e.mean, 5.6 ± 2.1 × 10 −7 m ) caused a reduction of the response, with a maximum of 49.2 ±4.3%. Bicuculline did not inhibit these responses to GABA. 4 Baclofen (ED 50 ±s.e.mean, 6.8± 1.4 × 10 −7 m ) produced a similar inhibition (47.4±3.2% maximum) but 3‐APS had no effect. 5 GABA (10 −4 m ) had no effect on the tone of isolated mesenteric or internal carotid arteries from the rabbit, whether or not the tone was increased with 5‐HT. Similarly, GABA (10 −4 m ) did not produce any change in the responses to transmural stimulation in isolated mesenteric or internal carotid arteries. 6 These findings are consistent with the presence of two types of GABA receptor on the rabbit basilar artery.