A STUDY ON THE CARDIAC ACTION OF THIAMINE DERIVATIVES IN ISOLATED GUINEA PIG ATRIA (I)

Abstract

During the investigation of atrial anaphylaxis, positive inotropic effects of various drugs have been compared with that of the anaphylactic manifestation in the isolated guinea pig atria, it was observed that thiamine derivatives increased the contractile force of the atrium. Thiamine propyl disulfide (TPD) and thiamine tetrahydrofurfuryl disulfide (TTFD) are allithiamine derivatives discovered by Fujiwara (1), having a marked vitamin B1 action on the process of glucose and lipid metabolism in the body because these compounds readily penetrate the living tissue. Clinically these drugs are used for the treatment, not only of vitamin B, deficiency but also, of various heart diseases, postoperative intestinal paralysis etc, and their effects have been reported (2-4). However, nothing more than effect of these drugs on energy metabolism of the cardiac muscles has been known. Very few investigation has been attempted to elucidate the nature of their clinical effectiveness. Katsura (5) has reported the increased amplitude of the isotonic contraction and prolongation of the repolarization phase of the action potential of cardiac muscle fibers in the isolated toad heart by TPD. H. Simonnet et al. (6) have made a comparative study of pharmaco-dynamic action of thiamine and TPD but they could not obtain any findings to explain the effect of TPD. In the present study, attempts were made to describe a positive inotropic action of the thiamine derivatives and to compare their influences on transmembrane action potential pattern, potassium contracture and Ca uptake with those of other drugs that act inotropically in guinea pig atria in vitro.