GABA-mediated inhibition of pacemaker neurons of rostral ventrolateral medulla by clonidine in vitro.
In vitro, clonidine (1, 10, or 30 microM) dose-dependently and reversibly inhibited tonically active pacemaker neurons that correspond to the relatively fast-conducting reticulospinal vasomotor neurons of the rostral ventrolateral reticular nucleus of the medulla oblongata in rats. The clonidine-induced membrane-hyperpolarizing response of these neurons was abolished by either tetrodotoxin, bicuculline, a GABAA receptor antagonist, or 4,4'-diisothiocyano-1,2'-disulphonic stilbene acid, a Cl- channel blocker. We conclude that the clonidine-induced inhibition of the pacemaker neurons of the rostral ventrolateral reticular nucleus is indirect, mediated by synaptic release of gamma-aminobutyric acid (GABA) or GABA-like substances, which activate Cl- channels of the pacemaker neurons of the rostral ventrolateral reticular nucleus.
Sun
M K
MK
Department of Neurology and Neuroscience, Cornell University Medical College, New York, NY 10021, USA.
Reis
D J
DJ
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D001683:Biological Clocks; D003000:Clonidine / Q000494:pharmacology*; D058787:GABA-A Receptor Antagonists; D006321:Heart / Q000294:innervation*; D066298:In Vitro Techniques; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology / Q000187:drug effects*; D008564:Membrane Potentials / Q000187:drug effects; D008839:Microelectrodes; D009474:Neurons / Q000187:drug effects*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D012154:Reticular Formation / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D013779:Tetrodotoxin / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
D058787:GABA-A Receptor Antagonists; D013779:Tetrodotoxin; D005680:gamma-Aminobutyric Acid; C018564:dihydro-DIDS; D003000:Clonidine; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D001640:Bicuculline