Intracellular calcium variation in heparin-capacitated bovine sperm.
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 [Ca2+]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 (R1 = 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%). 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.
Córdoba
M
M
Facultad de Ciencias Veterinarias, Universidad de Buenos Aires, Argentina.
Santa-Coloma
T A
TA
Beorlegui
N B
NB
Beconi
M T
MT
D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology; D002417:Cattle; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005711:Gallopamil / Q000494:pharmacology; D006493:Heparin / Q000494:pharmacology*; D007211:Indoles / Q000494:pharmacology; D008297:Male; D008301:Maleimides / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology; D015398:Signal Transduction; D013075:Sperm Capacitation / Q000187:drug effects*; D013094:Spermatozoa / Q000378:metabolism*; D019311:Staurosporine / Q000494:pharmacology
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D004791:Enzyme Inhibitors; D007211:Indoles; D008301:Maleimides; D005711:Gallopamil; D006493:Heparin; D011493:Protein Kinase C; D019311:Staurosporine; C070515:bisindolylmaleimide I; D002118:Calcium