Linked Life Data

8663919

Source:http://linkedlifedata.com/resource/pubmed/id/8663919

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1996-8-5
pubmed:abstractText
This study examined the effect of metal ions Ca2+, Mg2+, and Mn2+ and sonication on ejaculated frozen-thawed bovine sperm adenylate cyclase activity, and whether cAMP levels in sperm changed during capacitation with heparin. The sperm adenylate cyclase was almost insensitive to Ca2+ at concentrations up to 10 mM when cold-shocked homogenized spermatozoa were used. Adenylate cyclase activity, as observed by cAMP formation (pmol/mg protein/min), did not increase significantly in the presence of 5 mM Mg2+. However, a 40-fold stimulation (cAMP 400-800 pmol/mg protein/min) occurred in the presence of 5 mM Mn2+. Although Ca2+ per se had no effect, it acted synergistically with Mg2+ and Mn2+ in stimulating sperm adenylate cyclase. Adenylate cyclase activity was highest in cold-shocked, homogenized spermatozoa. Sonication of cold-shocked spermatozoa resulted in loss of adenylate cyclase activity, and a logarithmic decrease in cAMP production (1,155.5 to 109.7 pmol cAMP) occurred when sonication was increased from 2 x 5 to 2 x 25 s on ice. Cyclic AMP levels in spermatozoa incubated under non-capacitating conditions, both untreated and treated with glucose or heparin plus glucose, remained higher (P < 0.01) compared with those incubated with heparin for the first 4 h of incubation. When spermatozoa were incubated under non-capacitating conditions, cAMP levels increased (P < 0.01), especially during the first hour of incubation, and then declined gradually throughout the incubation. In contrast, cAMP levels of heparin-treated spermatozoa declined gradually for 3 h, at which time they began to rise, peaked at 4 h and then remained fairly stable until 6 h. Glucose antagonized the effect of heparin on adenylate cyclase activity but not for more than 4 h. We conclude that: i) Ca2+ stimulates adenylate cyclase in the presence of Mg2+; ii) homogenization by sonication reduces cyclase activity in frozen-thawed, cold-shocked spermatozoa; iii) adenylate cyclase activity is inhibited by heparin but rises concomitantly with the onset of capacitation (after 4 h) in spermatozoa incubated under capacitating conditions; and iv) glucose, which prevents capacitation by heparin, antagonizes heparin action on adenylate cyclase.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0926-5287
pubmed:author
pubmed:issnType
Print
pubmed:volume
36
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
221-32
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
Adenylate cyclase activity increases concomitantly with the onset of capacitation in heparin-treated bovine spermatozoa.
pubmed:affiliation
Département des sciences animales, Faculté d'agriculture, Centre de recherche du CHUL Université Laval, Quebec, Canada.
pubmed:publicationType
Journal Article