Ventricular electrical instability in the conscious dog: effects of psychologic stress and beta adrenergic blockade.
The effect of psychologic stress on cardiac vulnerability was examined in 10 conscious dogs. The repetitive extrasystole threshold was employed as a measure of susceptibility to ventricular fibrillation. Instrumental aversive conditioning constituted a stressful environment. The repetitive extrasystole threshold decreased by nearly 50 percent during 3 days in which the animals were exposed to the stressful environment. When Tolamolol hydrochloride, a cardioselective beta adrenoceptor blocking agent, was administered before a stress session, the repetitive extrasystole threshold was unaltered from the control value. Thus, stress-evoked changes in cardiac vulnerability are mediated through the sympathetic nervous system.
D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D004285:Dogs; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects; D006329:Heart Conduction System / Q000187:drug effects / Q000503:physiopathology*; D006339:Heart Rate / Q000187:drug effects; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D009200:Myocardial Contraction / Q000187:drug effects; D011292:Premedication; D011412:Propanolamines / Q000008:administration & dosage / Q000494:pharmacology*; D012032:Refractory Period, Electrophysiological / Q000187:drug effects; D013315:Stress, Psychological; D014693:Ventricular Fibrillation / Q000503:physiopathology
D011412:Propanolamines; D007545:Isoproterenol