Association between seminal plasma carnitine and sperm mitochondrial enzymatic activities

Cellular parameters of the seminogram have been previously shown to correla te with L-carnitine concentration in the seminal fluid. Carnitine is involv ed in a variety of metabolic processes playing an important role in maintai ning an active oxidative phosphorylation (OXPHOS). Recently, we have found a significant association between the specific activities of the respirator y chain complexes and the seminogram parameters and here we have studied th e relationship between the spermatozoa OXPHOS activities and L-carnitine co ncentration in the seminal plasma. Carnitine, but not prostatic secretions, positive and significantly correlate with mitochondrial respiratory comple x activities and the citric acid cycle enzymes citrate synthase and succina te dehydrogenase. It is remarkable that the ratios of the respiratory chain complexes to citrate synthase or succinate dehydrogenase, significant but negatively correlated with L-carnitine concentration. As carnitine in semin al plasma is secreted from the epididymis our results strongly suggest that relationships between carnitine secretion, seminal quality and OXPHOS acti vities could be because of a parallel response to the same regulatory event .