O-2-HYDROXY-N-(4-NITROPHENYL)-PROPANESULPHONAMIDE, A NEW CLASS OF GABA(B) RECEPTOR ANTAGONIST IN CENTRAL AND PERIPHERAL PREPARATIONS

Racemic no-2-hydroxy-N-(4-nitrophenyl)-propanesulphonamide (AHPNS), a sulphonamide analog of GABA, reversibly and competitively antagonised the concentration-dependent depression of cholinergic twitch contracti ons by baclofen, in the electrically stimulated guinea-pig isolated il eum, with a pA(2) of 4.0 +/- 0.2. In the rat neocortex, maintained in Mg2+-free medium, AHPNS (100-500 mu M) also reversibly antagonised the baclofen (10 mu M)-induced suppression of spontaneous discharges. AHP NS is a new class of GABA(B) receptor antagonist that has central and peripheral blocking actions.