Depressor effects of isoguvacine propyl ester and isoarecaidine propyl ester due to stimulation of central GABA receptors in the cat.

Upon their simultaneous administration into the left and right vertebral artery of the cat, 2 x 30 micrograms isoarecaidine propyl ester (IAPE) and 2 x 30 micrograms isoguvacine propyl ester (IGPE) induce hypotension and bradycardia. These effects were antagonized by (+)-bicuculline or picrotoxin. IAPE is rapidly hydrolyzed by cat brain tissue in vivo. It is suggested that both IAPE and IGPE are prodrugs and that the corresponding carboxylic acids are GABA agonists and responsible for the cardiovascular effects evoked.