Abstract
Summary
Spermatozoan motility of whole bull semen incubated aerobically at 37° in 0.9% NaCl saline was inhibited by 10-3 to 10-7 M ouabain, an effect opposite to that observed for testosterone. Preincubation for 30 to 45 min with ouabain blocked the effect of testosterone, while preincubation with testosterone only partly blocked the effect of ouabain. When equimolar ouabain and testosterone were incubated together motility of spermatozoa initially tended to be intermediate between the individual effects of ouabain and testosterone. However, by the second hour of incubation ouabain inhibition was similar to that observed in ouabain treatment alone. Ouabain showed a synergistic effect when testosterone was added at only one-third the molar concentration of ouabain.
The ability of ouabain and testosterone to block the action of each other suggests that their mechanisms are interrelated. However, they do not appear to have common binding sites because pretreatment of spermatozoa with ouabain (which is irreversibly bound) did not diminish the capacity of spermatozoa to bind testosterone.
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