Defective lipid metabolism in the failing heart.

The metabolism of long chain fatty acids was investigated in the failing heart of guinea pigs with chronic constriction of the ascending aorta. Homogenates prepared form failing hearts exhibited (a) a decreased capacity to oxidize palmitic acid (failure = 0.50 +/- 0.06 mumole/g of protein per 20 min; control = 1.09 +/- 0.10); (b) a reduced level of carnitine, a myocardial constituent which serves to control the oxidation rate of long chain fatty acids in the heart (failure = 0.91 +/- 0.10 mumole/g wet weight; control = 1.69 +/- 0.10); and (c) an increased rate of palmitate incorporation into triglycerides and lecithin. Exogenous carnitine effected a restoration of the defective palmitate metabolism of the homogenates towards normal. In contrast to long chain fatty acid oxidation, glucose oxidation by the failing heart was not impaired. As a consequence of this selective lesion in energy substrate utilization, the failing heart might be forced to rely on substrates other than long chain fatty acids for its major energy supply.