| 11566731 |
Vernet P, Fulton N, Wallace C, Aitken RJ: Analysis of reactive oxygen species generating systems in rat epididymal spermatozoa. Biol Reprod. 2001 Oct;65(4):1102-13.
Epididymal sperm maturation culminates in the acquisition of functional competence by testicular spermatozoa. The expression of this functional state is dependent upon a redox-regulated, cAMP-mediated signal transduction cascade that controls the tyrosine phosphorylation status of the spermatozoa during capacitation. Analysis of superoxide anion (O2 (-.)) generation by rat epididymal spermatozoa has revealed a two-component process involving electron leakage from the sperm mitochondria at complexes I and II and a plasma membrane NAD (P) H oxidoreductase. Following incubation in a glucose-, lactate-, and pyruvate-free medium (-GLP), O2 (-.) generation was suppressed by 86% and 96% in caput and cauda spermatozoa, respectively. The addition of lactate, malate, or succinate to spermatozoa incubated in medium -GLP stimulated O2 (-.) generation. This increase could be blocked by rotenone and oligomycin (R/O) in the presence of malate or lactate but not succinate. Stimulation with all three substrates, as well as spontaneous O2 (-.) production in +GLP medium, was blocked by the flavoprotein inhibitor, diphenylene iodonium. Diphenylene iodonium, but not R/O, suppressed NAD (P) H-induced lucigenin-dependent chemiluminescence. This NAD (P) H-dependent enzyme resided in the sperm plasma membrane and its activity was regulated by zinc and uncharacterized cytosolic factors. Reverse transcription-polymerase chain reaction analysis indicated that the sperm NAD (P) H oxidoreductase complex is quite distinct from the equivalent leukocyte system. |
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