Dual regulation of the T-type Ca(2+) current by serum albumin and beta-estradiol in mammalian spermatogenic cells.
This study provides evidence for a novel mechanism of voltage-gated Ca(2+) channel regulation in mammalian spermatogenic cells by two agents that affect sperm capacitation and the acrosome reaction (AR). Patch-clamp experiments demonstrated that serum albumin induced an increase in Ca(2+) T current density in a concentration-dependent manner, and significant shifts in the voltage dependence of both steady-state activation and inactivation of the channels. These actions were not related to the ability of albumin to remove cholesterol from the membrane. In contrast, beta-estradiol significantly inhibited Ca(2+) channel activity in a concentration-dependent and essentially voltage-independent fashion. In mature sperm this dual regulation may influence capacitation and/or the AR.
Espinosa
F
F
Department of Genetics and Molecular Physiology, Institute of Biotechnology, UNAM, Avenida Universidad 2001, Cuernavaca, Mexico.
López-González
I
I
Muñoz-Garay
C
C
Felix
R
R
De la Vega-Beltrán
J L
JL
Kopf
G S
GS
Visconti
P E
PE
Darszon
A
A
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020747:Calcium Channels, T-Type / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology*; D017136:Ion Transport / Q000187:drug effects; D008297:Male; D018408:Patch-Clamp Techniques; D012709:Serum Albumin / Q000494:pharmacology*; D013094:Spermatozoa / Q000378:metabolism*
D020747:Calcium Channels, T-Type; D012709:Serum Albumin; D004958:Estradiol; D002118:Calcium