title: Aprotinin and a seminal plasma factor inhibit the motility of demembranated reactivated rabbit spermatozoa.
abstract: The demembranation and reactivation of ejaculated rabbit spermatozoa have been studied. ATP, Mg, glutamate, dithiothreitol (DTT), and Tris-HCl were found to be essential for a good reactivation. With this experimental model, we investigated the effects of protease inhibitors on the reinitiation of movement by ATP and on the movement of already motile spermatozoa. Soybean trypsin inhibitor (STI) prolonged the length of reactivation by 7- to 8-fold, whereas pepstatin, antithrombin III, phenylmethylsulfonyl fluoride (PMSF), and alpha-1-antitrypsin had no significant effect. Aprotinin (1.5 micrograms/ml) and leupeptin (50 micrograms/ml) completely prevented the reinitiation of movement by ATP; aprotinin at the same concentration even blocked the movement of motile spermatozoa. A tissue-specific seminal plasma factor could also prevent both the reinitiation of movement and the movement of motile spermatozoa. However, it took 2-3 times the amount of seminal plasma to stop the movement than to prevent the reinitiation of movement. The inhibitor in the seminal plasma is most probably not a protease or an aprotinin-like protease inhibitor since a partially purified preparation of the seminal plasma inhibitor does not hydrolyze a trypsin substrate, is not inhibited by protease inhibitors and has no significant capacity to inhibit trypsin. The data suggest that aprotinin and the seminal plasma inhibitor block movement through different mechanisms. Aprotinin and the seminal plasma inhibitor represent two new tools to study the regulation of sperm movement.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D007611:Aprotinin / Q000494:pharmacology*; D002462:Cell Membrane; D000242:Cyclic AMP / Q000494:pharmacology; D005260:Female; D008297:Male; D029584:Prostatic Secretory Proteins; D011480:Protease Inhibitors / Q000494:pharmacology; D011506:Proteins; D011817:Rabbits; D029589:Seminal Plasma Proteins; D013081:Sperm Motility / Q000187:drug effects*; D013094:Spermatozoa / Q000166:cytology*
chemical_list: D029584:Prostatic Secretory Proteins; D011480:Protease Inhibitors; D011506:Proteins; D029589:Seminal Plasma Proteins; C043076:beta-microseminoprotein; D000255:Adenosine Triphosphate; D007611:Aprotinin; D000242:Cyclic AMP