The effect of beta-adrenoceptor antagonists alone and in combination with a GABA-elevating agent on isoniazid-induced convulsions in rats.

A delay in the onset of isoniazid-induced convulsions was found in rats pretreated with the beta 2-adrenoceptor blocker, butoxamine and the nonspecific beta-blocker, propranolol. In these animals the convulsive responses were inhibited in a dose dependent manner. These compounds were found to be effective even after the induction of convulsions. The beta 1-blocker, acebutolol was able to protect rats only when injected prior to the challenge. The anticonvulsant effect of acebutolol and propranolol but not that of butoxamine was found to be enhanced in animals pretreated with a gamma-aminobutyric acid (GABA) elevating agent, aminooxyacetic acid (AOAA). The findings indicate that the GABA-mediated anticonvulsant action of AOAA seems to be additive with that resulting from beta 1 but not beta 2-blockade.