Effects of cibenzoline on cardiac function and metabolism in the rat heart-lung preparation

Background and objective Although there is concern that cibenzoline, an ant idysrhythmic drug for the treatment of Ventricular and supraventricular dys rhythmias, may be associated with dose-dependent inhibition of myocardial c ontractility there are few reports about the relationship between myocardia l metabolism and cardiac function when it is used. The present study was de signed to investigate the effects of cibenzoline on cardiac function and me tabolism. The effects of cibenzoline on cardiac function and myocardial met abolism were assessed in the isolated rat heart-lung preparation. Methods Thirty-two male Wistar-ST rats were divided into four groups: contr ol, and those to receive cibenzoline, either 300, 900 or 3000 ng mL(-1). Th e cibenzoline was administered into the perfusate 5 min after the start of perfusion. Heart rates in the 3000 ng mL(-1) group were significantly lower than those in the control group. Cardiac output in the 3000 ng mL(-1) grou p at 15 and 30 min was significantly lower than in the control group. In al l groups, values for %LV dP/dt max (the ratio of values at each time to tho se at 5 min) at 20, 25, 30 min were significantly higher than at 5 min. Myo cardial adenosine triphosphate concentration in the 3000 ng mL(-1) group wa s significantly lower than in controls. There was no difference between gro ups in the lactate/pyruvate ratio. Conclusion The therapeutic range of cibenzoline has few effects on cardiac function and metabolism, although concentrations 10 times greater may cause a deterioration in myocardial metabolism.