Calcium Channel Antagonists Inhibit the Acrosome Reaction and Bind to Plasma Membranes of Sea Urchin Sperm

As a prerequisite to fertilization, sea urchin sperm undergo an acrosome reaction that is mediated in part by increased permeability to Ca2+, with an attendant rapid, massive intracellular Ca2+accumulation. The acrosome reaction is inhibited by Ca2+channel antagonists, including verapamil, D600, and...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1985-03, Vol.82 (5), p.1460-1464
Main Authors: Kazazoglou, Theodossia, Schackmann, Robert W., Fosset, Michel, Shapiro, Bennett M.
Format: Article
Language:English
Subjects:
Acrosome - drug effects
Acrosome reaction
acrosomes
Animals
Binding sites
Biological and medical sciences
Calcium
calcium antagonists
Calcium Channel Blockers - metabolism
Calcium Channel Blockers - pharmacology
Cell Membrane - analysis
Cell Membrane - metabolism
Cell membranes
Dihydropyridines
Echinodermata
Fundamental and applied biological sciences. Psychology
Invertebrates
Male
Membrane Proteins - analysis
Ova
Paracentrotus lividus
Plasma interactions
Sea Urchins
Spermatozoa
Spermatozoa - drug effects
String theory
Strongylocentrotus purpuratus
Structure-Activity Relationship
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Summary:As a prerequisite to fertilization, sea urchin sperm undergo an acrosome reaction that is mediated in part by increased permeability to Ca2+, with an attendant rapid, massive intracellular Ca2+accumulation. The acrosome reaction is inhibited by Ca2+channel antagonists, including verapamil, D600, and dihydropyridines such as nitrendipine, nimodipine, and nisoldipine. To examine the interaction of Ca2+antagonists with sperm, a plasma membrane preparation enriched for Na+, K+-ATPase was isolated from sea urchin sperm. These plasma membranes specifically bound [3H]nitrendipine and [3H]verapamil at concentrations similar to those that inhibit the acrosome reaction. The binding of verapamil was sigmoidal and half-maximal at 1 μ M. There was a high specificity in the binding interaction, since by competition binding verapamil, (-)-D600, and (+)-D600 had different relative Kdvalues, 11, 2.5, and 0.5 μ M, respectively. These data suggest that sperm mediate the Ca2+influx required for induction of the acrosome reaction via Ca2+channels with properties similar, but not identical, to those of other excitable tissues.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.82.5.1460