ELECTROENCEPHALOGRAPHIC STUDIES ON THIAMINE DERIVATIVES IN THE RABBIT

Abstract

It has been demonstrated by several investigators that the cardiac effects of alkyldisulfide derivatives of thiamine are considerably different from those of thiamine HCl. Misu et al. (1) in this laboratory have observed the effects of thiamine derivatives on the spontaneous contraction and transmembrane potentials of the isolated rabbit's atria. Thiamine tetrahydrofurfuryl disulfide (TTFD) prolonged the repolarization phase of the action potential and antagonized the shortening of the same phase caused by hypoxia. Furthermore, TTFD prolonged the time length required to abolish the spontaneous contraction of the atria induced by hypoxia, but thiamine HCl did not so. The positive inotropic effect and prolongation of the repolarization time in the isolated guinea-pig's atria have been confirmed by Nakazawa and Ueno (2) and Kanno (3) in TTFD and thiamine propyldisulfide but not in thiamine HCl. The blocking effects of thiamine derivatives on the neuro-muscular junction (4-6) and the sympathetic ganglion (7, 8) have been reported. Thiamine was also described to inhibit the activity of cholinesterase (9). These findings indicate the possibility that thiamine derivatives, especially the alkyldisulfides, exert cholinergic excitement in the central nervous system. The present report deals with effects of thiamine derivatives on the spontaneous EEG of rabbits, when these drugs are administered into the ear marginal vein, common carotid artery or lateral ventricle.