Mitochondrial function in heart muscle from patients with idiopathic dilated cardiomyopathy

Objective: To study the mitochondrial respiratory chain enzyme activities i n patients with idiopathic dilated cardiomyopathy (IDC). Methods: Mitochond rial respiratory chain enzyme activities were assessed spectrophotometrical ly in left ventricular tissue of 17 patients with IDC undergoing cardiac tr ansplantation, as well as in two groups of controls: a group of six patient s suffering from ischemic dilated cardiomyopathy (IC) also undergoing cardi ac transplantation, and a group of 17 organ donors considered normal from a cardiac point of view. Cytochrome b gene from three IDC patients whose com plex III activity was particularly low and from three controls was also seq uenced. Results: We found that complex III enzymatic activity was lower not only in IDC but also in IC patients when compared with normal controls. Wh en analysing cytochrome b gene we only found neutral polymorphisms previous ly described. Conclusions: In view of such results, we believe that the dec rease of respiratory chain complex III activity found in some car;es of IDC is a secondary phenomenon, and not due to a primary mitochondrial disease. (C) 2000 Elsevier Science B.V. All rights reserved.