R-(-)-beta-phenyl-GABA is a full agonist at GABAB receptors in brain slices but a partial agonist in the ileum.

R-(-)-beta-phenyl-GABA has been compared at GABAB receptors using cortical and ileal preparations. R-(-)-beta-phenyl-GABA (EC50 = 25 microM) was a less potent full agonist than R,S-(+/-)-baclofen (EC50 = 2.5 microM), in depressing CA1 population spikes of rat hippocampal slices, and 5 times less potent in attenuating the spontaneous discharges of rat neocortex. However, R-(-)-beta-phenyl-GABA (100-400 microM) was only a weak partial agonist in the ileum. All these actions were sensitive to CGP 35348 (3-aminopropyl-(P-diethoxymethyl)-phosphinic acid) and therefore mediated by GABAB receptors.