Influence of acetylcholine, isoproterenol, quinidine and ouabain on effective refractory periods of atrial and ventricular myocardium in the dog.
Acetylcholine-, isoproterenol-, quinidine- and ouabain-induced variations of the effective refractory periods (E.R.P.) of the non-specialized atrial and ventricular tissue have been explored in the dog by the extra-stimulus method during total cardiopulmonary by-pass. Acetylcholine significantly shortens the E.R.P. of atrial fibers, but does not provoke any change in the ventricular tissue, whereas a parallel decrease of atrial and ventricular E.R.P. is noted with isoproterenol. Quinidine induces a larger increase of the E.R.P. in the atrium than in the ventricle. The ouabain-induced shortening of the E.R.P. in the atrium is more marked than in the ventricle but is followed by a secondary increase which depends on both time after injection and dose. Hypotheses about the mechanisms of these effects, their importance in fibrillation and their relation to clinical uses are discussed.
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D004285:Dogs; D004558:Electric Stimulation; D006325:Heart Atria / Q000187:drug effects; D006352:Heart Ventricles / Q000187:drug effects; D007545:Isoproterenol / Q000494:pharmacology*; D009200:Myocardial Contraction / Q000187:drug effects*; D009431:Neural Conduction / Q000187:drug effects*; D010042:Ouabain / Q000494:pharmacology*; D011802:Quinidine / Q000494:pharmacology*; D012032:Refractory Period, Electrophysiological / Q000187:drug effects*; D013997:Time Factors
D010042:Ouabain; D011802:Quinidine; D007545:Isoproterenol; D000109:Acetylcholine