Linked Life Data

7628375

Source:http://linkedlifedata.com/resource/pubmed/id/7628375

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
1995-9-1
pubmed:abstractText
Agonist-induced increases in cytoplasmic calcium concentration ([Ca2+]i) play a pivotal role in regulated exocytosis by promoting the fusion of secretory vesicles with the plasma membrane. In permeabilized and ATP-primed pituitary cells, increases in ambient [Ca2+]i stimulated the release of LH from gonadotrophs with an EC50 of 2-3 microM. In contrast, the responses of intact gonadotrophs to agonist stimulation by GnRH were characterized by transient [Ca2+]i elevations of up to 1.5 microM, followed by a plateau of 300-400 nM. The sensitivity of the exocytotic response of permeabilized cells to [Ca2+]i was significantly increased by GnRH, which reduced the EC50 for [Ca2+]i to the submicromolar concentration range. The stimulatory action of GnRH on LH release in permeabilized cells was not a consequence of intracellular Ca2+ release, but was associated with increased cytidine diphosphate diacylglycerol production. Activation of protein kinase C by phorbol esters caused a similar increase in the Ca2+ sensitivity of LH release from permeabilized cells, and this effect was not additive to that of GnRH. Furthermore, the GnRH-induced increase in the sensitivity of the exocytotic response to Ca2+ was attenuated by inhibitors of protein kinase C. These findings indicate that although elevated [Ca2+]i per se can promote LH release from permeabilized gonadotrophs, concomitant activation of protein kinase C is necessary to support exocytosis at the physiological [Ca2+]i levels that prevail in GnRH-stimulated intact cells. Such sensitization of the Ca(2+)-dependent secretory mechanism by protein kinase C may be an important step in the agonist-induced release of LH from pituitary gonadotrophs.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0013-7227
pubmed:author
pubmed:issnType
Print
pubmed:volume
136
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3398-405
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
Gonadotropin-releasing hormone-induced sensitization of calcium-dependent exocytosis in pituitary gonadotrophs.
pubmed:affiliation
Endocrinology and Reproduction Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
pubmed:publicationType
Journal Article