Factors Determining the Size of an Experimental Infarct
The left anterior descending coronary artery was occluded for 22.5, 45, 90, 180, and 360 min in anesthetized open-chest dogs and pigs and thereafter reperfused for 30 min. Myocardial oxygen consumption (MVO2) was varied in dogs by cholinergic stimulation (bradycardia) and by cutting of the right and left vagus nerves (tachycardia). Regional myocardial blood flow was measured with radioactive tracer microspheres at the end of the occlusion period and 5 and 30 min after reflow. Tissue content of adenine nucleotides and of phosphocreatine were determined in the subendo- and subepicardium of transmural biopsies at the end of reflow. Infarct size was determined with nitro blue tetrazolium and compared with risk region size.