Linked Life Data

1967144

Source:http://linkedlifedata.com/resource/pubmed/id/1967144

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1990-1-19
pubmed:abstractText
In AtT-20 cells somatostatin inhibits the secretion of adrenocorticotropic hormone (ACTH) through the activation of GTP binding proteins (G proteins) linked to second messengers such as calcium and cyclic AMP (cAMP). Recently, it has been proposed that there may be G proteins that regulate directly the exocytotic machinery. We have investigated whether somatostatin could inhibit secretion at a step distal to second messengers through a GTP binding protein. For these studies two experimental paradigms were used: (1) intact cells stimulated by calcium ionophores and (2) digitonin-permeabilized cells exposed to buffers of increasing Ca2+ concentrations. Somatostatin inhibited by 70% the ACTH release caused by the calcium ionophore ionomycin without modifying the ionophore-induced elevation in cytosolic [Ca2+]. This effect was cAMP independent because (1) it was observed in the presence of high concentrations of membrane-permeant cAMP analogues, and (2) it was not accompanied by a change in cAMP levels. The effect was also independent of the levels of activators of protein kinase C because it could be produced in the presence of high concentrations of phorbol esters. The action of somatostatin was prevented by pertussis toxin. In digitonin-permeabilized AtT-20 cells somatostatin inhibited release induced by calcium buffers in a GTP-dependent manner. These two observations indicate the involvement of a G protein. It is proposed that a G protein coupled to somatostatin receptors inhibits the intracellular machinery of secretion at a step distal to second messengers, perhaps at the exocytotic site.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0022-3042
pubmed:author
pubmed:issnType
Print
pubmed:volume
54
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
30-8
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1990
pubmed:articleTitle
Evidence that receptor-linked G protein inhibits exocytosis by a post-second-messenger mechanism in AtT-20 cells.
pubmed:affiliation
Istituto di Ricerche Farmacologiche Mario Negri, Consorzio Mario Negri Sud, Santa Maria Imbaro, Chieti, Italy.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't