Carnitine palmitoyltransferase in patients with cardiac ischemia due to atherosclerotic coronary artery disease and in patients with idiopathic dilated cardiomyopathy.

Cardiac ischemia is associated with an impairment in long-chain fatty acid metabolism. We studied carnitine palmitoyltransferase (CPT) in left ventricular biopsies of 6 transplant recipients with ischemia due to atherosclerosis, 4 patients with dilated cardiomyopathy, and 5 donor hearts. Total CPT activity was not significantly different between the three groups (7.9 +/- 3; 6.7 +/- 2, and 8 +/- 3 nmol/min/mg noncollagenous protein). Residual CPT activity after inhibition by malonyl-CoA (0.4 mM) was 38 +/- 11, 36 +/- 5 and 38 +/- 7%. There were no difference in IC50 values. Residual CPT activity after the addition of the detergent Triton X-100 (0.5%) was 58 +/- 17, 54 +/- 2 and 50 +/- 8% (nonsignificant). Our results suggest that (i) total CPT activity and (ii) the sensitivity of the interaction of CPT I with its regulator malonyl-CoA are not affected by cardiac ischemia, and (iii) the ratio of CPT I to CPT II is not altered in cardiac ischemia.