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Mouse sperm membrane potential: changes induced by Ca 2+
Author(s) -
Espinosa Felipe,
Darszon Alberto
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)00962-9
Subject(s) - chemistry , hyperpolarization (physics) , extracellular , depolarization , membrane potential , ouabain , valinomycin , biophysics , niflumic acid , sperm , calcium , trifluoperazine , ruthenium red , thapsigargin , amiloride , sodium , calmodulin , biochemistry , stereochemistry , biology , nuclear magnetic resonance spectroscopy , botany , organic chemistry
Mouse sperm resting membrane potential ( E r ) (−42±8.8 mV), determined with a potential sensitive dye, depended on extracellular K + and, in the absence of extracellular Ca 2+ ([Ca 2+ ] e ), on external Na + ([Na + ] e ). Ca 2+ addition (>5 μM) to sperm in Ca‐free media induced a transient hyperpolarization (Ca‐ith) which strongly depended on [Na + ] e and less on external Cl − ([Cl − ] e ). Cd 2+ and Mn 2+ (μM) mimicked the Ca 2+ effect, but not Ba 2+ . The Ca‐ith was partially inhibited by ouabain (74%, IC 50 = 5.8 μ M) and niflumic acid (38%, IC 50 = 240 μ M), indicating the participation of the Na‐K ATPase and Cl − channels. In Ca‐free low‐Na + media, Ca 2+ addition caused a depolarization sensitive to: nimodipine (25 μM), trifluoperazine (12.5 μM) and Mg 2+ (1.2 mM), suggesting the participation of Ca 2+ channels. Since some inhibitors of the sperm Ca‐ith block the acrosome reaction (AR), both processes may share transport systems.