[Action of acetylcholine on the mammalian auricle influenced by verapamil].
The action of acetylcholine (ACh) and verapamil (VePa) on the action potential (V(t)), phase plane trajectories of V(t) (dV/dt--V(t) -- plot) and isotonic contractions were investigated using an isolated vegal innervated preparation from rabbit atrium (method I) and investigating action potentials from atrial trabeculae by means a modified sucrose gap technique (method II). If the VePa-concentration increases to 4 mg/1 the duration of the action potential decreases at 20 and 90% repolarization (driving frequencies 2 s-1). In the VePa-solutions phase plane trajectories of the action potential did not change significantly. ACh application favours the disappearance of a region in the repolarization phase plane plot showing anomalous rectification (d(--dV/dt)/dV less than 0) both by control conditions and verapamil. The electrotropic ACh-and vagal effects will be unchanged by verapamil. The inotropic ACh-and vegal action (method I) increases by VePa (2 mg/1). The action of ACh and verapamil will be analysed using a mathematical model for reconstructing the repolarization phase of mammalian atrial myocardium action potentials.
D000109:Acetylcholine / Q000494:pharmacology*; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D016275:Atrial Function; D006321:Heart / Q000502:physiology*; D006325:Heart Atria / Q000187:drug effects; D008433:Mathematics; D009200:Myocardial Contraction / Q000187:drug effects*; D011817:Rabbits; D014630:Vagus Nerve / Q000502:physiology; D014700:Verapamil / Q000494:pharmacology*
D014700:Verapamil; D000109:Acetylcholine
Azetylcholinwirkungen auf das Vorhofmyokard unter dem Einfluss von Verapamil.