Abstract
The relation of the chemical structure of thiamine alkyldisulfides to the positive inotropic action was studied by using isolated guinea pig atria. From the results obtained, it was suggested that the S-S bond of thiamine alkyldisulfides is indispensable for the production of the positive inotropic action. The antagonistic action of thiamine tetrahydrofurfuryldisulfide (TTFD) against metabolic inhibitors was also studied and it was confirmed that TTFD antagonizes the depression of atrial contraction induced by meralluride and pentobarbital. Depression of atrial contraction due to dinitrophenol or cyanide was antagonized by TTFD to some extent. However, TTFD was incapable of antagonizing the depression caused by monoiodoacetic acid. As a result of perfusion experiments on the isolated guinea pig heart, it was shown that the ventricle increased its contractile force by TTFD only when a perfusion fluid containing blood cells was used. In the case of a perfusion fluid lacking blood, a negative inotropic action was induced by TTFD. Thus, it was suggested that thiamine alkyldisulfides show different patterns of cardiac action with metabolic changes in heart muscles.
