title: Increased calcium-ion influx is a component of capacitation of spermatozoa.
abstract: Capacitation (modifications required for gamete fusion) is produced by incubating guinea-pig spermatozoa in vitro in a chemically defined medium. It is shown that during such incubation a net uptake of Ca2+ by the sperm occurs in two distinguishable phases. An initial loose association of Ca2+, possibly to surface sites, is unaffected by agents (Mg2+, inhibitors of mitochondiral function) that prevent or delay the exocytotic spermatozoal acrosome reaction. The time course of a secondary Ca2+ uptake parallels or slightly precedes the time course of the acrosome reaction. This parallelism is maintained during a variety of treatments that either expedite (local anaesthetics, ionophore A23187, Triton X-100) or delay (Mg2+, low external Ca2+) the acrosome reaction. We conclude that the secondary Ca2+ influx described herein apparently serves to link alterations of the spermatozoal membrane to subsequent contractile and secretory components of the capacitation sequence.
mesh_terms: D000177:Acrosome / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D013075:Sperm Capacitation; D013081:Sperm Motility / Q000187:drug effects; D013094:Spermatozoa / Q000378:metabolism*; D013997:Time Factors
chemical_list: D002118:Calcium