Article date: 1991/1/1
PubMed ID: 1646362
Journal name: Life sciences (ISSN: 0024-3205)
The modulatory actions of gamma-aminobutyric acid (GABA) receptor agonists and omega-conotoxin GVIA (CTX) on sympathetic and sensory nerves were examined on contractile responses of the perfused rat mesentery to transmural nerve stimulation (TNS). GABA and baclofen, a selective GABAB receptor agonist, significantly inhibited vasoconstrictor responses to TNS, while muscimol, a selective GABAA receptor agonist, had no effect. In the guanethidine treated and methoxamine-contracted mesentery, TNS caused a vasodilator response which was unaffected by GABA. CTX (10(-8) M) markedly suppressed the vasoconstrictor response to TNS, but did not affect vasodilator responses. These findings suggest that in the rat mesentery: (1) GABA receptors modulate the activity of sympathetic nerves via prejunctional GABAB receptors, but do not influence sensory nerves, and (2) calcium channels which participate in sympathetic nerve activation have different properties than calcium channels in capsaicin-sensitive sensory nerves.
Author List: Li Y J, Duckles S P
Publication Types: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.
Substances mentioned in the article: Calcium Channels; Peptides, Cyclic; Receptors, GABA-A; Muscimol; gamma-Aminobutyric Acid; omega-Conotoxin GVIA; Baclofen;
Mesh terms: Animals; Baclofen/pharmacology; Calcium Channels/physiology; Electric Stimulation; Male; Mesenteric Arteries/drug effects; Muscimol/pharmacology; Peptides, Cyclic/pharmacology; Rats; Rats, Inbred Strains; Receptors, GABA-A/physiology; Sympathetic Nervous System/drug effects; Vasoconstriction/drug effects; Vasodilation/drug effects; gamma-Aminobutyric Acid/pharmacology; omega-Conotoxin GVIA;