抄録
It is very important to know the pharmacodynamic effects of a new thiamine derivatives, because the so-called "mass therapy" of thiamine derivative is being carried out without proven action mechanisms. As O, S-dicarbethoxythiamine (DCET) had an quinidine-like antiar-rhythmic effects on myocardium as well as striated muscle, it was studied whether DCET had an quinidine-like antiarrhythmic effects in situ preparations or not. Methacholine induced A-V block in cats was effectively antagonized by the DCET administration as quinidine. These effects, however, were not specific to DCET, for the similar antiarrhythmic effects were observed by the thiamine administration. Only slight antiarrhythmic effects were observed by the DCET administration in the epinephrine or epinephrine-petroleum ether induced ventricular arrhythmia in cats, while quinidine effectively antagonized to the arrhythmias at the same dose range as in the methacholine arrhythmias. In ouabain arrhythmias, β-adrenergic blocker propranolol was the only compound which markedly increased the ouabain doses required for various arrhythmias. Threshold voltages in the ventricular fibrillation of rabbit were elevated in the following order : quinidine>procaine amide>DCET. It may be concluded that vagotonic atrial arrhythmias are effectively suppressed by the DCET administration.
