Intracellular Ca2+ in capacitated sperm

What is it about?

This report investigates the mechanisms by which heparin induces capacitation of sperm. Capacitation was determined with chlortetracycline and intracellular calcium concentration, [Ca2+]i, with FURA 2-AM After 15 minutes incubation with heparin, [CaZ+]i was increased 60% over basal, reaching a plateau thereafter. Sixty percent of calcium entry was inhibited by methoxy-verapamil, suggesting that activation, of voltage dependent calcium channels (VDCC) may be involved in the process. A significant correlation (R2 = 0.88, p<0.006) was found between the percentage of capacitated spermatozoa and the [Ca2+]i increase. The effects of heparin on both processes were blocked by the protein kinase C (PKC) inhibitors staurosporine (100%) and GF-109203X (90%).

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Why is it important?

It is concluded that heparin may induce sperm capacitation and calcium influx mainly through VDCC (approx. 60%), and also through other membrane systems (40%). Both systems of calcium entry as well as the capacitation process appear to involve on PKC activity.