These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Calcium-dependent increase in adenosine 3',5'-monophosphate and induction of the acrosome reaction in guinea pig spermatozoa.
    Author: Hyne RV, Garbers DL.
    Journal: Proc Natl Acad Sci U S A; 1979 Nov; 76(11):5699-703. PubMed ID: 93280.
    Abstract:
    Experiments were designed to determine the interrelationship between cyclic AMP and Ca(2+) during the processes of sperm capacitation and the acrosome reaction. In minimal culture media containing pyruvate and lactate as substrates, guinea pig spermatozoa required a minimum of 1.0-1.5 hr to capacitate in the presence of 1.7 mM Ca(2+) and a minimum of 0.5-1.0 hr to capacitate in the absence of added Ca(2+). Sperm cyclic AMP concentrations were increased by as much as 30-fold within 0.5 min after addition of cells to various media containing Ca(2+), and the concentrations then remained increased for up to 4 hr. When the cells were added to several Ca(2+)-deficient media, however, cyclic AMP concentrations increased only about 3-fold within 0.5 min and then returned to basal concentrations within 2 min. D-600, a calcium transport antagonist, completely blocked the Ca(2+)-induced increase in sperm cyclic AMP concentrations. In contrast to capacitation, the acrosome reaction failed to occur in the absence of extracellular Ca(2+). After capacitation of spermatozoa in a Ca(2+)-free medium, addition of Ca(2+) caused an increase in sperm cyclic AMP concentrations within 1 min and a maximal number of spermatozoa showing an acrosome reaction within 10 min. The addition of 1-methyl-3-isobutylxanthine along with Ca(2+) had a synergistic effect on the increase in cyclic AMP. Neither 1-methyl-3-isobutylxanthine nor 8-Br cyclic AMP induced an acrosome reaction in capacitated spermatozoa in the absence of Ca(2+), but both significantly decreased the time required for maximal expression of the acrosome reaction in the presence of Ca(2+). These results suggest that the sperm acrosome reaction is associated with both a primary transport of Ca(2+) and a Ca(2+)-dependent increase in sperm cyclic AMP concentrations. Because a cyclic AMP analogue did not induce an acrosome reaction in the absence of added Ca(2+), the increase in sperm cyclic AMP concentrations induced by Ca(2+) probably reflects one of a number of Ca(2+)-dependent events associated with the acrosome reaction.
    [Abstract] [Full Text] [Related] [New Search]