[Effects of methylflavonolamine hydrochloride on physiologic properties of isolated guinea pig atrium].

The effects of methylflavonolamine hydrochloride (MFA) on the contractility, excitability, automaticity and functional refractory period (FRP) were studied in isolated guinea pig atrium. MFA (5 and 75 mumol/L) decreased the contractility, increased the threshold concentration of adrenaline to evoke automaticity of the left atria, depressed the spontaneously beating right atria and lengthened FRP. MFA, at 75 mumol/L but not at 5 mumol/L, and shifted the intensity duration curve to the right. Our results suggest that suppression of the spontaneous and the evoked automaticity and prolongation of FRP may be related to its antiarrhythmic action.