Effect of noncoronary blood flow upon myocardial mitochondrial function during hypothermic anoxic arrest

Mongrel dogs (23) were subjected to the experimental study characterizing the effect of noncoronary blood flow upon myocardial mitochondrial respiration. Anoxic arrest for 60 minutes was obtained by cross-clamping of the aorta under hypothermic cardiopulmonary bypass, and heart was reperfused for 10 minutes, then heart was excised to obtain the endocardium, epicardium of the left ventricle and ventricular septum for study of mitochondrial function and myocardial blood flow. Myocardial blood flow was measured with carbonized plastic tracer 46Sc during cross-clamping of the aorta. Noncoronary blood flow showed equal distribution in the left ventricle and septum with flow of 0.16 +/- 0.23 ml/ min/100g (endocardium). Mitochondrial respiratory function following 60 minutes of hypothermic anoxic arrest at 20 degrees C recovered to normal level, and also no correlation was demonstrated between noncoronary blood flow during cross-clamping of the aorta and mitochondrial respiratory function. It was concluded that noncoronary blood flow was negligible with respect to the oxygen demand at 20 degrees C of myocardial temperature, and that noncoronary blood flow during cross-clamping of the aorta was not correlated to mitochondrial protection from ischemia.