The ventromedullary hypotensive effect of muscimol in the anaesthetized cat.
Muscimol, a rigid analogue of GABA, was injected into the CNS of urethane-anaesthetized, normotensive cats. Bilateral microinjections of a small dose of muscimol (100 ng/kg, 0.5 microliter on each side) in the nucleus reticularis lateralis (NRL) induced hypotension. The marked fall in blood pressure obtained by injecting 1 microgram/kg of muscimol unilaterally into the NRL is completely reversed by subsequent local administration of bicuculline (5 microgram/kg, 0.5 microliter), a specific GABA antagonist. These data confirm that a GABAergic inhibitory system modulates the pressor tonic structures localized in the region of the NRL and that the anteroventral part of the medulla oblongata includes a trigger zone for the hypotensive action of muscimol.
D000758:Anesthesia; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D001933:Brain Stem / Q000187:drug effects*; D002415:Cats; D007022:Hypotension / Q000139:chemically induced*; D009118:Muscimol / Q000008:administration & dosage / Q000494:pharmacology*; D010080:Oxazoles / Q000494:pharmacology*; D013238:Stereotaxic Techniques
D010080:Oxazoles; D009118:Muscimol; D001640:Bicuculline