Anion channel blockers differentially affect t-type Ca2+ currents of mouse spermatogenic cells, ?1E currents expressed inXenopus oocytes and the sperm acrosome reaction

Voltage‐dependent Ca2+ channel subunit expression and immunolocalization in mouse spermatogenic cells and sperm

“…Alternatively, although a fraction of these α 1 subunits could reach the plasma membrane, they could give rise to currents that resemble the T‐type as reported for recombinant HVA Ca 2+ channel pore‐forming subunits expressed under particular conditions [25]. In addition, transcripts for at least two novel ion‐conducting α 1 subunits (α 1G , α 1H ) are present in spermatogenic cells and may encode T‐type channels [17], and interestingly enough, in a recent report Dolphin and colleagues demonstrated that HVA Ca 2+ channel auxiliary subunits including β 1 directly interact with α 1G to increase membrane localization of functional recombinant α 1G channels expressed in COS‐7 cells and Xenopus oocytes [26]. Moreover, most of what we know regarding the physiology of Ca 2+ channels in spermatozoa has been obtained in studies employing pachytene spermatocytes and round spermatids which are not the developmental stages immediately preceding mature sperm.…”

“…Patch‐clamp studies have revealed the presence of only T‐type Ca 2+ currents in spermatogenic cells [12–14]. However, transcripts for a number of VDCC α 1 subunits have been identified in these cells, including α 1A , α 1E and α 1C encoding HVA [15–17], as well as α 1G and α 1H [17] encoding T‐type channels. Evidence for expressed α 1 proteins was not provided until recently, when immunocytochemical data showed that three Ca 2+ channel α 1 subunits (A, C and E) are present and regionally localized in mammalian mature sperm [18,19].…”

Dual regulation of the T‐type Ca2+ current by serum albumin and β‐estradiol in mammalian spermatogenic cells

“…Spermatogenic cells were obtained as described previously [13]. Briefly, testes from adult CD1 mice were excised and suspended in ice‐cold dissociation solution.…”

Ca2+Entry through Store-operated Channels in Mouse Sperm Is Initiated by Egg ZP3 and Drives the Acrosome Reaction

“…The transient response mechanism had the anticipated characteristics of a lowvoltage-activated (LVA) T-type Ca 2ϩ channel, including a similar time course of activation and inhibitor sensitivity (Arnoult et al, 1999). LVA Ca 2ϩ channel genes are expressed during rodent spermatogenesis (Espinosa et al, 1999), and the associated currents were detected by whole cell patch clamp methods (Hagiwara and Kawa, 1984;Arnoult et al, 1996aArnoult et al, , 1997Arnoult et al, , 1998Liévano et al, 1996;Santi et al, 1996). Finally, channel activation was associated with acrosome reactions (Arnoult et al, 1996a).…”