Intravenous aspirin at reperfusion does not reduce infarct size in the dog with a residual critical stenosis.
Platelet-related events being associated with the increment of infarct size at reperfusion in the presence of a residual stenosis, we tested in dogs whether intravenous aspirin (ASA) could limit infarct size. The left anterior descending coronary artery was occluded for 90 min and reperfused for 6 h in the presence of a residual critical stenosis. Controls received saline, and treated groups were given 2, 6, or 12 mg/kg ASA, i.v., 5 min before reperfusion. Infarct size did not differ significantly between groups (control, 43.80+/-6.28%; ASA, 2 mg/kg: 41.07+/-7.78%; ASA, 6 mg/kg: 37.55+/-3.44%; ASA, 12 mg/kg: 29.40+/-5.41%), as well as transmural collateral blood flow and [111In]-platelet accumulation in the infarcted myocardium (2.5-3.6 x 10(5) platelets/g). However, myocardial neutrophil accumulation was significantly reduced (p < 0.05) in groups given 6 (15.0+/-2.6 x 10(6)/g tissue) and 12 mg/kg (18.4 +/-3.8) ASA, but not in the 2-mg/kg group (21.0+/-5.2), as compared with control group (32.0+/-7.2). Ex vivo platelet aggregation to collagen was abolished during reperfusion in all treated groups (p < 0.05). Transcardiac arteriovenous differences in 6-keto-PGF1alpha were reduced significantly 1 h after reperfusion in groups given 6 or 12 mg/kg ASA (94.7+/-13.1 and 71.7+/-19.2 pg/ml, respectively) but not in the 2-mg/kg group (178.3+/-78.2 pg/ml), as compared with control (405.4+/-171.6 pg/ml). ASA-insensitive platelet activation at the site of stenosis or inhibition by ASA of prostacyclin production by jeopardized myocardium may explain the observed lack of benefit of ASA.
Libersan
D
D
Laboratory of Experimental Pathology, Montreal Heart Institute, Québec, Canada.
Quan
E
E
Merhi
Y
Y
Uzan
A
A
Laperrière
L
L
Latour
J G
JG
D015121:6-Ketoprostaglandin F1 alpha / Q000097:blood; D000758:Anesthesia; D000818:Animals; D001241:Aspirin / Q000627:therapeutic use*; D001772:Blood Cell Count / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D003327:Coronary Disease / Q000473:pathology*; D004285:Dogs; D005260:Female; D007238:Infarction / Q000473:pathology*; D007262:Infusions, Intravenous; D008297:Male; D008315:Malondialdehyde / Q000032:analysis; D009504:Neutrophils / Q000378:metabolism; D010974:Platelet Aggregation / Q000187:drug effects*; D015427:Reperfusion Injury / Q000188:drug therapy*
D008315:Malondialdehyde; D015121:6-Ketoprostaglandin F1 alpha; D001241:Aspirin