Mitochondrial dysfunction reduces aerobic energy production and results in symptoms from various tissues, depending on metabolic demands. Mitochondrial adenosine triphosphate (ATP) is essential for sperm motility. Sperm motility was investigated in a patient with a mitochondrial disease caused by reduced activity of the mitochondrial enzyme complexes I and IV, and in two control subjects. Spermatozoa were cultured in media containing various energy substrates. Motility was judged by light microscopy, and ultrastructure by transmission electron microscopy. In the patient with mitochondrial disease, 12% of the spermatozoa were motile in the medium containing only glucose. There was a three-fold increase in motile spermatozoa when pyruvate and succinate were present together with glucose. In contrast, the spermatozoa of both control subjects had best motility in the presence of substrates for complex I, and no further increase was observed when succinate was added. Glucose and pyruvate enter the respiratory chain at complex I, and succinate at complex II. Electron microscopy of spermatozoa from the patient with mitochondrial disease revealed mitochondria with increased matrix, thickening of membranes, parallelization of cristae and lipid inclusions, which are characteristic findings in mitochondrial disorders. Abnormal mitochondria were also found in a spermatid, suggesting that the ultrastructural changes of mitochondria are primary rather than secondary to degeneration of the spermatozoa. The results indicate that mitochondrial dysfunction causes reduced sperm motility in some men.

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A mutation at base pair (bp) 3243 in mitochondrial DNA has been associated with mitochondrial myopathy, encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS). A mutation at bp 8344 has been described as the cause of myoclonic epilepsy and ragged-red fiber disease (MERRF). Mitochondrial DNA was analyzed in a family with symptoms and signs consistent with MERRF. The DNA regions flanking bp 3243 and bp 8344 were amplified using the polymerase chain reaction, and the products were digested with restriction enzymes. The MELAS mutation at bp 3243 was found, but not the mutation at bp 8344. This illustrates the diverse clinical manifestations of the MELAS mutation.

The aim of this study was to assess by quantitative methods whether the assumed metabolic disturbance underlying preeclampsia would be reflected in muscle cell composition of lipid, mitochondria, or glycogen. We have reported mitochondrial dysfunction in preeclampsia, and since accumulation of lipid in skeletal muscle is a feature in mitochondrial disorders, our hypothesis was that preeclamptic women would have an increased content of triglyceride droplets. Quantitative investigation of the skeletal muscle ultrastructure was performed in 10 women with severe preeclampsia and in 6 normotensive pregnant women. Biopsy specimens from musculus rectus abdominis were taken during cesarean section and prepared for electron microscopy. Random pictures were taken by transmission electron microscopy, and point-counting stereology was performed. Preeclamptic women did not have a higher lipid volume fraction than normotensive pregnant women, and we had to reject our hypothesis. On the contrary, there was a tendency towards a lower triglyceride volume fraction in preeclampsia. We did not detect differences in relative volumes of mitochondria or glycogen in skeletal muscle between the two groups.