Anticholinergic effects of disopyramide and quinidine on guinea pig myocardium. Mediation by direct muscarinic receptor blockade.

• DOI: 10.1161/01.res.47.6.855
• Publication Date: 2012-06-12T00:17:09Z
• Authors: M J Mirro; A S Manalan; J C Bailey; A M Watanabe
• Keywords: Disopyramide; Quinidine; Physostigmine; Procainamide

We studied the interaction of disopyramide, quinidine, and procainamide with cardiac muscarinic receptors. In electrophysiological experiments, effects procainamide, atropine were determined on spontaneously depolarizing guinea pig right atria (GPRA) both in presence absence pharmacologically induced (physostigmine) cholinergic stimulation. All four agents demonstrated a concentration-dependent antagonism negative chronotropic physostigmine. The order anticholinergic potency was greater than disopyramide quinidine procainamide. ability to antagonize physostigmine slowing stereoselective, (+)disopyramide (-)disopyramide. contrast, non-stereoselective, = quinine. parallel we compete radiolabeled receptor antagonist [3H] quinuclidinyl benzilate ([3H]QNB) for binding receptors crude homogenates GPRA membrane vesicles from canine ventricular myocardium. inhibited [3H]QNB by studies identical that physiological studies. > Quinidine only slightly more potent quinine inhibiting Interaction antiarrhythmic drugs satisfied criteria competitive interaction. data this study localize receptor.