Coenzyme Q10 content in different parts of the normal human heart

Coenzyme Q10 (CoQ10) and citrate synthase (CS) activities were analysed in the myocardium of brain-dead organ donors (14-40 years). Different parts of the heart were studied: right and left auricular appendage, right and left atrium, right ventricle (septum and free wall) and left ventricle (septum, free wall, and papillary muscle). Freeze-dried, dissected myocardial samples were analysed for CoQ10 content by HPLC and CS activity by fluorometric technique. CoQ10 content in the normal human myocardium was lowest in auricular appendages and atria (0.25 +/- 0.06 mg X g-1 dry muscle), intermediate in right ventricle (0.37 +/- 0.05 mg X g-1 dm) and highest in left ventricle (0.42 +/- 0.07 mg X g-1 dm). CS activity showed the same relationship between these locations as CoQ10. The results suggest that there exist differences in CoQ10 content between different parts of the normal human myocardium. These differences were closely related to the differences in CS activity between corresponding parts. The differences between different parts of the heart may be related to divergent work demand, and the constant relationship between CS and CoQ10 may be related to their coupling to the mitochondrial oxidative metabolism.