title: Changes in the myocardial area at risk, infarct size, and collateral flow following nicardipine infusion in dogs.
abstract: The area at risk of infarction after an acute occlusion of the left anterior descending coronary artery was defined in anesthetized dogs using the distribution of 99mTc-labelled albumin microaggregates and Monastral blue dye. In thirteen dogs, it was determined that these two particulate labels identified identical areas of unperfused myocardium. In a second group of dogs (n = 12), the risk areas determined at 10 (99mTc-labelled macroaggregates) and at 180 min (Monastral blue dye) were found to be identical, with no change in collateral blood flow, indicating the absence of a spontaneous change in underperfused myocardium over this time. In a third group of dogs (n = 17) nicardipine was infused (10 micrograms.kg-1.min-1 for 5 min, followed by 8 micrograms.kg-1.min-1 for 165 min). This resulted in a significant and sustained fall (32 +/- 4 mmHg; 1 mmHg = 133.32 Pa) in mean arterial blood pressure but no significant change in collateral blood flow was found, except for a marginal increase in the center of the ischemic zone. Area at risk and infarct sizes were also not significantly different between the latter two groups (18.2 +/- 4.1 vs. 21.6 +/- 4.0% of left ventricle). In this model, the magnitude of the area at risk appears to be determined early after a coronary occlusion and appears to be unmodified by treatment with nicardipine begun after the occlusion.
authors.affiliation: Department of Physiology, Faculty of Medicine, University of Ottawa, Ont., Canada.
authors.forename: R
authors.initials: R
authors.lastname: Sandhu
authors.forename: G P
authors.initials: GP
authors.lastname: Biro
mesh_terms: D000818:Animals; D001157:Arterial Occlusive Diseases / Q000150:complications; D001783:Blood Flow Velocity / Q000187:drug effects; D003097:Collateral Circulation / Q000187:drug effects; D003326:Coronary Circulation / Q000187:drug effects; D003331:Coronary Vessels; D004285:Dogs; D005260:Female; D007262:Infusions, Intravenous; D008297:Male; D009203:Myocardial Infarction / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D009529:Nicardipine / Q000008:administration & dosage*
chemical_list: D009529:Nicardipine