The effects of tertiapin-Q on responses of the sinoatrial pacemaker of the guinea-pig heart to vagal nerve stimulation and muscarinic agonists.

Using Langendorff preparations of the guinea-pig heart, we have examined the participation of the acetylcholine (ACh)-activated potassium channel, IK,ACh, in the bradycardia produced by electrical stimulation of the vagus (parasympathetic) nerve and muscarinic agonists (ACh and bethanecol, bolus i.a.).