Ethanol inhibition of baroreflex bradycardia: role of brainstem GABA receptors.
Ethanol administered i.v. or into the nucleus tractus solitarii (NTS) of rats anaesthetized with urethane inhibits baroreflex bradycardia elicited by phenylephrine. This effect is prevented or reduced by pretreatment of rats with 3-mercaptopropionic acid, bicuculline, or RO 15-4513. Intra-NTS injection of muscimol also inhibits baroreflex bradycardia and causes a pressor response which is potentiated by intra-NTS ethanol. It is proposed that ethanol inhibits baroreflex bradycardia, at least in part, by potentiating the action of endogenous gamma-aminobutyric acid (GABA) at GABAA receptors in the NTS or its vicinity.
Varga
K
K
Laboratory of Physiologic and Pharmacologic Studies, National Institute on Alcohol Abuse and Alcoholism, Rockville MD 20852.
Kunos
G
G
D015097:3-Mercaptopropionic Acid / Q000494:pharmacology; D000758:Anesthesia; D000818:Animals; D001386:Azides / Q000494:pharmacology; D001569:Benzodiazepines / Q000494:pharmacology; D001640:Bicuculline / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D001933:Brain Stem / Q000502:physiology*; D000431:Ethanol / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects*; D008297:Male; D008845:Microinjections; D009118:Muscimol / Q000008:administration & dosage / Q000494:pharmacology; D011311:Pressoreceptors / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D011963:Receptors, GABA-A / Q000502:physiology*; D012018:Reflex / Q000187:drug effects*
D001386:Azides; D011963:Receptors, GABA-A; D001569:Benzodiazepines; D009118:Muscimol; D000431:Ethanol; C042957:Ro 15-4513; D015097:3-Mercaptopropionic Acid; D001640:Bicuculline