The role of calcium in maintaining motility in mouse spermatozoa

✍ Scribed by Heffner, Linda J. ;Storey, Bayard T.

• Publisher: John Wiley and Sons
• Year: 1981
• Tongue: English
• Weight: 623 KB
• Volume: 218
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402180314

✦ Synopsis

Abstract

Maintenance of mouse sperm motility requires exogenous Ca^+2^ in most, but not all, samples of epididymal spermatozoa. In these samples, the loss of motility with time is the same in Tris/NaCl buffer containing 1.7 mM Ca^+2^ (medium TNC) as it is in complete culture medium used for in vitro fertilization (medium CM) over the first 2 hours; spermatozoa in medium TNC lose motility at more rapid rate thereafter. The cation specificity for maintenance of motility is unusual in that both Sr^+2^ and Mg^+2^ substitute for Ca^+2^, with Mg^+2^ being the more effective. In the absence of Ca^+2^, these samples of mouse epididymal spermatozoa in Tris/NaCl buffer (medium TN) lose motility in about 30 minutes. If Ca^+2^ is added after incubation in TN for 15 minutes, motility is maintained as well as it is in medium TNC. If Ca^+2^ is added at 30 minutes, motility is partially restored. But if Ca^+2^ is added after 60 minutes, there is no restoration of motility. Spermatozoa suspended in medium TNC lose motility rapidly on addition of EGTA in excess of the Ca^+2^ present. Attempts to show uptake of Ca^+2^ by spectrophotometric assay, by effects of Ca^+2^ on oxidative metabolism, and by electron probe X‐ray microanalysis were unsucessful; motility is not maintained by entry of Ca^+2^ into the cells. Our results are consistent with a Ca^+2^ site on the plasma membrane and suggest that these sites function as oligomers of ordered subunits whose structure requires Ca^+2^. In the absence of Ca^+2^, the ability to form the oligomer is lost with time, possibly due to an irreversible conformational change.