The effects of gamma-hydroxybutyrate on the membrane properties of guinea-pig pars compacta neurons in the substantia nigra in vitro.
The effects of gamma-hydroxybutyrate have been studied on the membrane properties of pars compacta neurons within the guinea-pig substantia nigra maintained in vitro. The effects of gamma-hydroxybutyrate are to (i) lower input resistance, (ii) hyperpolarize the cell membrane in a dose-dependent manner and (iii) facilitate calcium conductances. These effects are resistant to the blockade of sodium channels with tetrodotoxin and blockade of potassium channels with tetraethylammonium or 4-aminopyridine. Furthermore, these effects are only partially blocked by high doses of the GABA receptor antagonist bicuculline: indeed the effects of the GABA receptor agonist muscimol can be differentiated from those of gamma-hydroxybutyrate in that the latter is sensitive to application of barium ions. The results suggest that gamma-hydroxybutyrate acts to increase utilization of calcium, which in turn leads to an initiation of calcium-dependent events. The functional consequences of these effects of gamma-hydroxybutyrate are discussed with regard to its possible endogenous modulatory actions.
Harris
N C
NC
University Department of Pharmacology, Oxford, U.K.
Webb
C
C
Greenfield
S A
SA
D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D005260:Female; D006168:Guinea Pigs; D006885:Hydroxybutyrates / Q000494:pharmacology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D012978:Sodium Oxybate / Q000494:pharmacology*; D013378:Substantia Nigra / Q000187:drug effects / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
D006885:Hydroxybutyrates; D013779:Tetrodotoxin; D012978:Sodium Oxybate; D001640:Bicuculline