title: Scorpion toxins that block T-type Ca2+ channels in spermatogenic cells inhibit the sperm acrosome reaction.
abstract: The acrosome reaction (AR) is a Ca(2+)-dependent event required for sperm to fertilize the egg. The activation of T-type voltage-gated Ca(2+) channels plays a key role in the induction of this process. This report describes the actions of two toxins from the scorpion Parabuthus granulatus named kurtoxin-like I and II (KLI and KLII, respectively) on sperm Ca(2+) channels. Both toxins decrease T-type Ca(2+) channel activity in mouse spermatogenic cells and inhibit the AR in mature sperm. Saturating concentrations of the toxins inhibited at most approximately 70% of the whole-cell Ca(2+) current, suggesting the presence of a toxin-resistant component. In addition, both toxins inhibited approximately 60% of the AR, which is consistent with the participation of T-type Ca(2+) channels in the sperm AR.
authors.affiliation: Department of Development Genetics and Molecular Physiology, Institute of Biotechnology, National Autonomous University of Mexico, Avenida Universidad 2001, Col. Chamilpa, CP 62100, Cuernavaca, Mor., Mexico.
authors.forename: Ignacio
authors.initials: I
authors.lastname: López-González
authors.forename: Timoteo
authors.initials: T
authors.lastname: Olamendi-Portugal
authors.forename: José L
authors.initials: JL
authors.lastname: De la Vega-Beltrán
authors.forename: Jurg
authors.initials: J
authors.lastname: Van der Walt
authors.forename: Karin
authors.initials: K
authors.lastname: Dyason
authors.forename: Lourival D
authors.initials: LD
authors.lastname: Possani
authors.forename: Ricardo
authors.initials: R
authors.lastname: Felix
authors.forename: Alberto
authors.initials: A
authors.lastname: Darszon
mesh_terms: D020101:Acrosome Reaction / Q000187:drug effects*; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D020747:Calcium Channels, T-Type / Q000502:physiology*; D002478:Cells, Cultured; D004553:Electric Conductivity; D007700:Kinetics; D008297:Male; D051379:Mice; D009498:Neurotoxins / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D012604:Scorpion Venoms / Q000494:pharmacology*; D013093:Spermatogonia / Q000187:drug effects / Q000502:physiology; D013094:Spermatozoa / Q000187:drug effects* / Q000502:physiology
chemical_list: D002121:Calcium Channel Blockers; D020747:Calcium Channels, T-Type; D009498:Neurotoxins; D012604:Scorpion Venoms; C118444:kurtoxin