U 89843A were administered at doses of 10 mg/kg intravenously and 25 mg/kg orally as 5-10 mg/mL solutions in propylene glycol USP. Doses were administered to fasted Male Sprague-Dawley Rat (N = 3/compound) in a crossover design with a 1 week washout period between treatments.

The whole cell configuration of the patch clamp technique was used to record the GABA mediated Cl- currents in human embryonic kidney cells (A293), expressing various combinations of GABAA receptor subunit. Patch pipettes were prepared from borosilicate glass tubes and were fire-polished to a tip resistance of 0.5 to 2 megaohms when filled with a solution containrng (millimolar): CsC1, 140; ethylene glycol bis(ı-aminoethyl ether)-N,N’-tetraacetic acid, 11; MgC12, 4; AlP, 2; and 4-(2-hydroxyethyl)-1-piperazineethanesulfothc acid, 10, pH 7.3. Cells were bathed in an external solution containing (millimolar): NaC1, 135; KC1, 5; MgCl2, 1; CaCl2, 1.8; and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, 5, pH 7.2 (normal saline). GABA and U 89843A were dissolved in the external solution to a final concentration of 5 mkM, unless medicated otherwise, and was applied through a U-tube placed within 100 mkL of the target cell. The current was recorded with an Axopatch 1D amplifier and a CV-4 headstage (Axon Instrument Co., Burlingame, CA). A Bh-1 bath headatage was used to compensate for changes in bath potentials. The currents were recorded with a Gould (Cleveland, OH) Recorder 220. GABA currents were measured at the holding potential of -60 mV at room temperature (21-24OC)