Strontium supports human sperm capacitation but not follicular fluid-induced acrosome reaction

MARÍN BRIGGILER CI; VAZQUEZ-LEVIN MH; GONZALEZ ECHEVERRÍA MF; BLAQUIER JA; TEZON JG; MIRANDA PV

BIOLOGY OF REPRODUCTION

Año: 1999 vol. 61 p. 673 - 680

0006-3363

The ability of strontium (Sr++) to replace calcium (Ca++) in maintaining human sperm function has still not been completely characterized. In the present study, acrosome reaction (AR) inducibility in response to human follicular fluid (hFF) was compared in spermatozoa incubated in either Ca++ or Sr++ containing media. Other events related to sperm capacitation, such as protein tyrosine phosphorylation and hyperactivation, as well as zona pellucida (ZP) recognition in both conditions were also analyzed. Spermatozoa incubated overnight in the presence of Sr++ were unable to undergo the AR when exposed to hFF. Nevertheless, when incubated in this condition and then transferred to medium with Ca++, spermatozoa responded to hFF similarly to cells incubated throughout in the presence of Ca++. The sperm protein tyrosine phosphorylation pattern, the percentage of sperm motility and hyperactivation were similar after incubation in Ca++ or Sr++ containing media. In both conditions, the same binding capacity to homologous ZP was observed.  Similar results were obtained when EGTA was added in order to chelate traces of Ca++ present in Sr++ medium. From these results it can be concluded that Sr++ can substitute Ca++ in supporting capacitation related events and ZP binding, but not hFF- induced AR of human spermatozoa.