[Prevention of adrenaline-induced arrhythmia by a calmodulin blocker, trifluoroperazine]

Adrenergic arrhythmias were induced in isolated rat hearts with epinephrine in a concentration of 5.10(-5) M in the perfusing solution. The rhythm disturbance was accompanied by a pronounced depression of contractility. It was found that the preliminary administration of the calmodulin blocker trifluoperazine (10(-6) M) decreased the duration of arrhythmias and the latency of their development, the contractility remaining at a higher level than in control. Verapamil administered into the perfusing solution did not significantly affect the latency of arrhythmias and reduced the duration of arrhythmias and the cardiotonic effect of epinephrine to a lesser extent than trifluoperazine. The mechanism is under discussion, by which the calmodulin blocker has a more pronounced cardioprotective antiarrhythmic effect than the Ca-channel blocker.