The effect of temperature and chloride ions on the stimulation of [3H]flunitrazepam binding by the muscimol analogues THIP and piperidine-4-sulfonic acid.

THIP and piperidine-4-sulfonic acid (PSA) interact with [3H]GABA binding sites and have GABAmimetic efficacy in vivo, but fail to enhance benzodiazepine receptor binding performed at 0 degree C. However, when [3H]flunitrazepam binding is determined at elevated temperature (30 or 37 degrees C), THIP and PSA display potent chloride ion-dependent stimulatory effects. These results resolve apparent discrepancies between the properties of GABA receptors observed in vivo and in vitro, and they suggest that the modulation of benzodiazepine receptor binding investigated at physiological temperatures can be used as an experimental system for the characterization of GABA receptors.