Gamma-aminobutyric acid receptor on vascular smooth muscle of dog cerebral arteries.

Gamma-aminobutyric acid (GABA) had a relaxant effect on dog cerebral arteries which was blocked only by picrotoxin, a known antagonist of GABA receptors. Other agents, adrenoceptor and ganglion blocking agents, atropine, reserpine, tetrodotoxin and ouabain, had no effect on the inhibitory action suggesting the existence of GABA receptors in the vascular smooth muscle of dog cerebral arteries.