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Holland MK, Storey BT: Oxygen metabolism of mammalian spermatozoa. Biochem J. 1981 Aug 15;198(2):273-80.
Generation of hydrogen peroxide by rabbit epididymal spermatozoa.. Rabbit spermatozoa from the cauda epididymis produced 0.7-0.8nmol of H (2) O (2)/min per 10 (8) cells at cell concentrations below 10 (7) cells/ml with linear dependence on cell concentration. Above 2 x 10 (7) cells/ml, the rate again became linear with cell concentration but decreased to 0.1-0.2nmol/min per 10 (8) cells. Spermatozoa treated with amphotericin B, which makes the plasma membrane highly permeable to low-molecular-weight compounds, showed a similar dependence of H (2) O (2) production rate on cell concentration; below 10 (7) cells/ml the rate was 0.3-0.4nmol/min per 10 (8) cells; above 2 x 10 (7) cells/ml, the rate was 0.1-0.2nmol/min per 10 (8) cells. Hypo-osmotically treated rabbit epididymal spermatozoa, a preparation useful for studying mitochondrial function in sperm [Keyhani & Storey (1973) Biochim. Biophys. Acta305, 557-565] produced 0.1-0.2nmol/min per 10 (8) cells in the absence of added substrates. The dependence of rate on cell concentration was linear from 10 (7) to 2.2 x 10 (8) cells/ml. This endogenous rate was unaffected by rotenone, but stimulated 4-fold by antimycin A. Addition of the mitochondrial substrates lactate plus malate increased the rate of H (2) O (2) production to 0.3nmol/min per 10 (8) cells. The decreased rate of H (2) O (2) production observed with intact sperm at high cell concentrations is attributed to reaction of H (2) O (2) with the cells, possibly with the plasma membrane, which is lost after hypo-osmotic treatment. Rabbit spermatozoa have glutathione peroxidase and glutathione reductase activities, but these seem to play little role in removal of H (2) O (2) generated. The rate at low cell concentration is taken to be the unperturbed rate. The sources of H (2) O (2) production in rabbit spermatozoa have been tentatively resolved into a low-molecular-weight component, lost after amphotericin treatment, a mitochondrial component and a rotenone-insensitive component that has not been identified. |
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