Abstract
The effects of riboflavin derivatives on the heart of open-chest dogs and the atrium isolated from guinea pigs were studied. FMN and DBRP did not show a marked effect on both preparations. In the dog preparation, FAD decreased the myocardial contractile force which was finally increased, prolonged PQ, QRS, QT and RR intervals, and decreased the blood pressure. The duration of the action of FAD was about five minutes. In the isolated atrium, FAD decreased the amplitude of contraction, DNRP showed the negative inatropic action on the dog heart, prolonged intervals of PQ, QRS, QT and RR, and the hypotension. DNRP, in higher doses, decreased the amplitude of contraction of the atrium. The action of TNR was similar to that of DNRP.
