Influence of Capacitation on SPM-Carbohydrate Binding
The effect of in vitro capacitation on sperm-carbohydrate interaction was studied using bicarbonate-enriched Tyrode media (T + BIC) either supplemented with heparin (T+BIC+Hep) or with heparin and glucose (T+BIC+Hep+Glu) and compared with Tyrode medium without bicarbonate (T—BIC). The subpopulation of sperm cells that showed signs of capacitation following incubation was quantified by the CTC-staining assay (for reference and staining patterns observed for bovine sperm).
Incubation for 4 h in capacitation media resulted in capaci-tation-specific CTC staining of approximately 75% of the cells (75% ± 2.6% for T+BIC+Hep and 75% ± 4.2% for T+BIC), whereas only 35% ± 3.4% in control medium (T—BIC) showed this CTC-labeling pattern (P < 0.001; n = 3). Higher glucose concentration (10 mM instead of 5 mM) in the capacitation media (T+BIC+Hep+Glu) partially inhibited the heparin effect, as only 56% ± 3.5% of sperm cells showed CTC capacitation staining in T+BIC+Hep+Glu (significantly different from the other capacitation media, n = 3; P < 0.05).