Source:http://linkedlifedata.com/resource/pubmed/id/10520128
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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
10
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| pubmed:dateCreated |
1999-12-1
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| pubmed:abstractText |
The objective of the present study was to further investigate the ionic mechanism of the action of GHRP-6 on male rat pituitary cells in culture. A synthetic hexapeptide, GHRP-6 stimulates the secretion of growth hormone both in vivo and in vitro. It is generally accepted that Ca2+ and protein kinase C but not cAMP are involved in the signal transduction pathway of the action of GHRP-6. Ca2+-influx through voltage-gated Ca2+ channels and mobilization of internal stored Ca2+ are thought to be responsible for an increase in cytosolic Ca2+ concentration. For activation of the voltage-gated Ca2+ channels, however, it is not determined whether the membrane Na+ permeability plays a role. To answer this question, we measured intracellular Na+ concentration of the pituitary cells with ion imaging technique. We found that GHRP-6 increased [Na+]i; the Na+ response depended on the presence of extracellular Na+ and was blocked by Gd3+, known as a blocker of nonselective cation channels but not by tetrodotoxin, a blocker of the voltage-gated Na+ channel; thapsigargin, an inhibitor of endoplasmic reticulum Ca2+ ATPase, had no effect on the response; Ca2+ chelating agent, BAPTA had no inhibitory effect on the response; ouabain, an inhibitor of Na+-K+ ATPase, did not block the rise in [Na+]i induced by GHRP-6; somatostatin, which hyperpolarizes the cells by activating K+ channels, suppressed the response. These data clearly showed that GHRP-6 increased [Na+]i in the rat pituitary cells including somatotrophs. The rise in [Na+]i is likely to be due to an increase in the membrane Na+ permeability which should depolarize the cells, thereby activating the voltage-gated Ca2+ channels. This process leads to an influx of Ca2+ and subsequent increase in [Ca2+]i which results in an exocytotic release of GH.
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| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:citationSubset |
IM
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| pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/1,2-bis(2-aminophenoxy)ethane...,
http://linkedlifedata.com/resource/pubmed/chemical/Anti-Inflammatory Agents,
http://linkedlifedata.com/resource/pubmed/chemical/Chelating Agents,
http://linkedlifedata.com/resource/pubmed/chemical/Egtazic Acid,
http://linkedlifedata.com/resource/pubmed/chemical/Enzyme Inhibitors,
http://linkedlifedata.com/resource/pubmed/chemical/Gadolinium,
http://linkedlifedata.com/resource/pubmed/chemical/Hormones,
http://linkedlifedata.com/resource/pubmed/chemical/Oligopeptides,
http://linkedlifedata.com/resource/pubmed/chemical/Ouabain,
http://linkedlifedata.com/resource/pubmed/chemical/Sodium,
http://linkedlifedata.com/resource/pubmed/chemical/Somatostatin,
http://linkedlifedata.com/resource/pubmed/chemical/Tetrodotoxin,
http://linkedlifedata.com/resource/pubmed/chemical/Thapsigargin,
http://linkedlifedata.com/resource/pubmed/chemical/gadolinium chloride,
http://linkedlifedata.com/resource/pubmed/chemical/growth hormone releasing hexapeptide
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| pubmed:status |
MEDLINE
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| pubmed:month |
Oct
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| pubmed:issn |
0953-8194
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| pubmed:author | |
| pubmed:issnType |
Print
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| pubmed:volume |
11
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| pubmed:owner |
NLM
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| pubmed:authorsComplete |
Y
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| pubmed:pagination |
795-800
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| pubmed:dateRevised |
2003-11-14
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| pubmed:meshHeading |
pubmed-meshheading:10520128-Animals,
pubmed-meshheading:10520128-Anti-Inflammatory Agents,
pubmed-meshheading:10520128-Cells, Cultured,
pubmed-meshheading:10520128-Chelating Agents,
pubmed-meshheading:10520128-Egtazic Acid,
pubmed-meshheading:10520128-Enzyme Inhibitors,
pubmed-meshheading:10520128-Extracellular Space,
pubmed-meshheading:10520128-Gadolinium,
pubmed-meshheading:10520128-Hormones,
pubmed-meshheading:10520128-Intracellular Fluid,
pubmed-meshheading:10520128-Male,
pubmed-meshheading:10520128-Oligopeptides,
pubmed-meshheading:10520128-Ouabain,
pubmed-meshheading:10520128-Pituitary Gland, Anterior,
pubmed-meshheading:10520128-Rats,
pubmed-meshheading:10520128-Rats, Wistar,
pubmed-meshheading:10520128-Sodium,
pubmed-meshheading:10520128-Somatostatin,
pubmed-meshheading:10520128-Tetrodotoxin,
pubmed-meshheading:10520128-Thapsigargin
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| pubmed:year |
1999
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| pubmed:articleTitle |
The effect of GHRP-6 on the intracellular Na+ concentration of rat pituitary cells in primary culture.
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| pubmed:affiliation |
Department of Physiology and Nippon Medical School, Tokyo, Japan. mkato@nms.ac.jp
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| pubmed:publicationType |
Journal Article
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