Article date: 1985/1/1
PubMed ID: 2988467
Journal name: Archives internationales de pharmacodynamie et de therapie (ISSN: 0003-9780)
GABA 100 microM inhibited neurogenic vasoconstrictor responses elicited in rabbit ear artery by field stimulation at various frequencies. GABA was ineffective both on resting tone and on noradrenaline (0.05-5 microM)- and high-K+ (24-54 mM)-induced tonic contraction. GABA effectiveness against field stimulation-induced vasoconstriction was inversely related to the frequency of stimulation. This action of GABA was mimicked by a selective GABAB agonist, such as baclofen (100 microM), but not by selective GABAA agonists as muscimol (100 microM) and homotaurine (100 microM). The selective GABAB antagonists 5-aminovaleric acid (1 mM) and homotaurine (100 microM) completely suppressed the inhibitory effect of GABA on field stimulation-induced vasoconstrictions. GABA action was partially reversed also by the selective GABAA antagonist picrotoxin (100 microM); however, this drug “per se” determined an increase in amplitude of field stimulation-induced contractions which in turn could have determined the minor effect of GABA. As a whole these data suggest that GABA can inhibit sympathetic neurotransmission in rabbit ear artery through the stimulation of a prejunctional receptor of the GABAB subtype.
Author List: Manzini S, Maggi C A, Meli A
Publication Types: Journal Article
Substances mentioned in the article: Amino Acids; Amino Acids, Neutral; GABA Antagonists; Picrotoxin; Taurine; Muscimol; gamma-Aminobutyric Acid; tramiprosate; 5-aminovaleric acid; Baclofen; Potassium; Norepinephrine;
Mesh terms: Amino Acids/pharmacology; Amino Acids, Neutral; Animals; Arteries/drug effects; Baclofen/pharmacology; Ear, External/blood supply; Electric Stimulation; GABA Antagonists; In Vitro Techniques; Male; Muscimol/pharmacology; Norepinephrine/pharmacology; Picrotoxin/pharmacology; Potassium/pharmacology; Rabbits; Sympathetic Nervous System/drug effects; Synaptic Transmission/drug effects; Taurine/analogs & derivatives; Vasoconstriction/drug effects; gamma-Aminobutyric Acid/pharmacology;