[The cholinolytic activity of the new anti-arrhythmia preparation Nibentan]

In the rabbit isolated right atrium and the rat atrial cells, a new class III antiarrhythmic drug Nibentan was shown to exert an anticholinergic effect contrary to Carbachol: the latter decreased the AP duration to 42 +/- 2% of the control whereas Nibentan restored it to 65 +/- 2%. The anticholinergic effect of the drug was found to be due to inhibition of the acetylcholine-activated potassium current: it was decreased by 79 +/- 3% in the rat isolated single atrial cells. In the rabbit isolated sino-atrial node, Nibentan prevented arrhythmogenic effects of vagal stimulation. The new drug may be quite efficient in treatment of flutter and atrial fibrillation.