Effects of action potential prolongation via different cellular mechanisms on the electrophysiological properties of rat and guinea-pig ventricular myocardium.
The effects of d-sotalol and the sea anemone toxin ATXII on the electrophysiological properties of rat and guinea-pig ventricular myocardium in vitro and on arrhythmias following coronary artery ligation in rat hearts in vivo were studied. ATXII (1-5 nM) prolonged the cardiac action potential of isolated papillary muscles and the effective refractory period of perfused hearts from both rats and guinea-pigs. In rat hearts, ATXII induced gross action potential prolongation and early afterdepolarizations at concentrations above 1 nM. In contrast, d-sotalol prolonged the action potential and effective refractory period of guinea-pig, but not of rat myocardium. Neither drug prevented arrhythmias in anaesthetized rats following coronary ligation.
Pfizer Central Research, Sandwich, Kent, U.K.
M
M
Gwilt
R C
RC
Williams
A J
AJ
Higgins
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000517:prevention & control; D002316:Cardiotonic Agents / Q000494:pharmacology*; D003064:Cnidarian Venoms / Q000494:pharmacology*; D004562:Electrocardiography; D005260:Female; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013015:Sotalol / Q000008:administration & dosage / Q000494:pharmacology*
D002316:Cardiotonic Agents; D003064:Cnidarian Venoms; C028800:toxin II (Anemonia sulcata); D013015:Sotalol