Myocardial removal of free fatty acids under normal and pathological conditions

Myocardial arteriovenous difference in free fatty acids (FFA) and coronary flow was determined in dogs under morphine-chloralose anesthesia. Fifteen minutes after the administration of insulin the A-V difference decreased. FFA uptake did not change significantly. Alloxan diabetes decreased the utilization per cent of FFA. Norepinephrine elevated myocardial uptake and arterial FFA. Hypoxia did not change FFA uptake. Hypothyroidism lowered myocardial uptake. Left ventricular O 2 consumption increased after administration of atropine in both normal and hypothyroid animals, whereas hypothyroidism was associated with a decreased value. A significant correlation was found in normal dogs between arterial FFA concentration and myocardial uptake. A different relationship suggested itself in hypothyroid animals. A correlation was also shown between the per cent of myocardial O 2 consumption calculated for complete oxidation of FFA and the myocardial R.Q.