Nonplatelet effects of aspirin during acute coronary occlusion: electrophysiologic and cation alterations in ischemic myocardium.
BACKGROUND
Mortality after acute myocardial ischemia has been reduced by aspirin (ASA) but mechanisms other than the antiplatelet effect have not been established. This article evaluates an antiarrhythmic action during sympathetic stimulation in the intact anesthetized dog with and without ischemia.


RESULTS
The ventricular fibrillation threshold (VFT) was examined before and after epinephrine (E) in normals (group I). A VFT reduction during E was normalized after 1 week of ASA (P<.01). Regional myocardial ischemia for 1 hour resulted in similar hypoperfusion in controls of group II and after ASA. Action potential responses in isolated superfused ischemic tissue showed prolonged repolarization (APD90) in response to E, which was normalized after ASA (P<.01). To assess the antiarrhythmic role of the anion in group III, Na salicylate was given. During 1 hour of ischemia, the VF incidence was reduced and cation abnormalities diminished in ischemic myocardium compared with untreated ischemia.


CONCLUSIONS
ASA antagonizes the reduction of the VFT induced by catecholamine in normals as well as the repolarization abnormality elicited by E during acute ischemia. The salicylate anion appears to be the active component in view of the efficacy in preventing VF during the early ischemic period.
Shehadeh
A A
AA
Department of Medicine, Division of Cardiology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, New Jersey, USA.
Arena
J
J
Moschos
C B
CB
Regan
T J
TJ
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001241:Aspirin / Q000494:pharmacology*; D003327:Coronary Disease / Q000150:complications*; D004285:Dogs; D004837:Epinephrine / Q000494:pharmacology; D008297:Male; D017202:Myocardial Ischemia / Q000150:complications*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D014693:Ventricular Fibrillation / Q000503:physiopathology / Q000517:prevention & control*
D010975:Platelet Aggregation Inhibitors; D001241:Aspirin; D004837:Epinephrine