title: [Characteristics of GABA-potentiating effect of harman].
abstract: Experiments on an isolated spinal cord of rats aged 9-15 days have shown that harmane (10(-7)-10(-5) M) enhances GABA-induced (1.10(-4) M) depolarization of primary afferents and hyperpolarization of motoneurones. The GABA-potentiating action of harmane on primary afferents is depicted by a bell-shaped curve with a maximum at 10(-5) M. The action is more pronounced the higher the concentration of chlorine ions in the medium. Harmane (10(-6)-10(-4) M) enhances spontaneous neuronal activity and evoked synaptic potentials (mono- and polysynaptic potentials of the ventral and dorsal roots) at the concentrations at which it exerts a direct depolarizing action on motoneurones and primary afferents. At higher concentrations the stimulant activity of harmane (10(-5)-10(-4) M) counteracts its GABA-potentiating effects.
mesh_terms: D000344:Afferent Pathways / Q000187:drug effects / Q000502:physiology*; D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D002713:Chlorine / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects; D006247:Harmine / Q000031:analogs & derivatives / Q000494:pharmacology*; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D013116:Spinal Cord / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
chemical_list: D000470:Alkaloids; D007473:Ion Channels; D006247:Harmine; D002713:Chlorine; D005680:gamma-Aminobutyric Acid; C005010:harman
vernacular_title: Osobennosti GAMK-potentsiruiushchego deĭstviia garmana.