As demonstrated previously, glucose must be metabolized to exert its positive effect on fusion. Although glycolysis is important for sperm functions such as hyperactivated motility, this metabolic pathway does not appear to be responsible for successful gamete fusion since its inhibition by phloretin or by iodoacetate (inhibitor of the glycolytic enzyme glyceraldehyde phosphate dehydrogenase ) in capacitated spermatozoa before insemination of zona-free oocytes and during gamete interaction did not prevent fusion. proventil inhaler
The reduced penetration into zona-free oocytes observed when spermatozoa were pretreated for 1 h with cytochalasin B, which was shown to diminish the PPP activity, suggests that this pathway is necessary to render the sperm fusogenic. In contrast, the lack of inhibition when 1) the oocytes were pretreated with cytochalasin B and 2) this inhibitor was present during gamete interaction indicates that the PPP activity is not essential either for the fusibility of the oocyte nor for the fusion step per se. Nie-mierko and Komar have also shown that pretreatment of sperm with cytochalasin B before insemination drastically decreased the fertilization rate (73.3% vs. 15.6%) when using cumulus-enclosed zona intact mouse eggs.