[Comparative study of the effect of some psychotropic substancces on the activity of brain Na+, K+-ATPase in vitro]

The activity of Na+, K+-ATPase from bovine brain in vitro was studied as affected by some neuroleptics (levomepromazine, chlorpromazine, perphenazine and haloperidol), antidepressants (imipramine and iproniazid) and psychostimulants (amphetamine) as well as by benactyzine and procaine. The degree of the enzyme inhibition by these drugs estimated by means of I 50 and apparent inhibitor constants (Ki) or rate constants (k) was different. Sensitivity of the brain Na+, K+-ATPase to the drugs decreased in the following order: levomepromazine, chlorpromazine, perphenazine, haloperidol, imipramine, iproniazid, benactyzine, procaine and amphetamine. Competition for the enzyme was revealed between sodium and some of the drugs investigated (levomepromazine, chlorpromazine, perphenazine and impramine) as well as between potassium and other drugs (haloperidol, genactyzine and amphetamine). It is suggested that the inhibition of the brain Na+, K+-ATPase by psychotropic drugs may be a part in the biochemical mechanism of their sedative-tranquilizing activity.