Effect of lidoflazine on membrane currents and contraction in voltage-clamped frog atrial fibers.

The effect of lidoflazine on action potential, membrane currents and contraction of frog atrial fibers was tested using the double sucrose voltage clamp technique. Lidoflazine was found to decrease the sodium conductivity of the heart cell membrane, probably by blocking the sodium channels. The availability of the sodium system at resting potential was slightly enlarged by lidoflazine and the recovery from inactivation was prolonged in most of the preparations tested. A small decrease of the slow inward current and a reduction of phasic and tonic tension was observed. The outward current at higher depolarizations was increased by lidoflazine resulting in a shortened action potential duration. The data suggest that lidoflazine's antifibrillatory properties are less pronounced than those of classical antiarrhythmic agents; but the slight antifibrillatory and negative inotropic effect might be helpful in the treatment of angina pectoris.