The calcium-induced curvature reversal of rat sperm is potentiated by cAMP and inhibited by anti-calmodulin

Cell Motil Cytoskeleton. 1991;20(4):316-24. doi: 10.1002/cm.970200407.


Rat sperm, demembranated with 0.1% Triton X-100, were used to explore the reversal in flagellar curvature induced by calcium ion. As reported earlier (Lindemann and Goltz, Cell Motil. Cytoskeleton, 10:420-431, 1988), the radius of curvature of the flagellar midpiece of rat sperm is controlled by the free Ca2+ concentration. A reversal of the direction of curvature (judged by the asymmetric sperm head) takes place at approximately 2.5 x 10(-6) M free Ca2+. In our current study, the time course of the curvature change, after elevating free Ca2+ to 3.5 x 10(-4) M, was utilized to assess the effects of the cAMP-kinase A pathway on the calcium response. In addition, calmodulin's involvement in this response was explored using anti-calmodulin and Cd2+. The activity state of the sperm models (which could be directly influenced through cAMP) was found to control the rate of curvature change in response to increased free Ca2+. In the most extreme case, fully quiescent sperm did not respond to Ca2+ at all, and cAMP-primed sperm models completed the response to Ca2+ in two minutes or less. Anti-calmodulin demonstrated strong inhibitory effects on the curvature reversal. Cadmium ion was also extremely potent at blocking the response to Ca2+, completely eliminating the curvature reversal at 2 x 10(-10) M free Cd2+. Based on these findings, it appears that the Ca(2+)-activated curvature reversal of rat sperm is potentiated by cAMP-dependent kinase and may be mediated through calmodulin.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Calcium / physiology*
  • Calmodulin / antagonists & inhibitors
  • Calmodulin / physiology*
  • Cell Membrane / physiology
  • Cyclic AMP / physiology*
  • Cytosol / physiology
  • Epididymis / cytology
  • In Vitro Techniques
  • Male
  • Rats
  • Sperm Motility / physiology
  • Sperm Tail / physiology*
  • Videotape Recording


  • Calmodulin
  • Cyclic AMP
  • Calcium