Studies on experimental myocardial infarction: dogs or baboons?

The extrapolation to humans of results obtained in experimental studies is a major problem in cardiovascular research. It is generally believed that non-human primates provide a better model for the study of experimental myocardial infarction than the canine or porcine heart. In the present study the transmural distribution of myocardial infarction and collateral flow were compared between dogs and baboons. In the open chest model, the left anterior descending coronary artery was ligated for 4 h. In the subepicardial and subendocardial portions of the left ventricle myocardial blood flow was measured with tracer microspheres, and infarct size and site were determined using triphenyl tetrazolium chloride. In baboons, mean(SD) subendocardial collateral flow was higher than subepicardial collateral flow (41.8(24.6) ml . min-1 X 100 g-1 vs 28.6(21.3) ml . min-1 X 100 g-1 (p less than 0.05)). Subendocardial infarct size (expressed as a percentage of the perfusion area) was smaller than subepicardial infarct size (50.3(8.5)% vs 61.2(9.6)% (p less than 0.001)). In dogs, subendocardial collateral flow was less than subepicardial collateral flow (10.2(6.0) ml . min-1 vs 13.6(4.6) ml . min-1 X 100 g-1 (p less than 0.05)), and subendocardial infarct size was greater than subepicardial infarct size (67.3(12.9)% vs 38.3(18.0)% (p less than 0.01)). When, irrespective of the species or transmural localisation, infarct size is related to collateral flow, expressed as a percentage of normal flow, a weak but significant correlation is obtained (r = 0.61, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)