Linked Life Data

1327724

Source:http://linkedlifedata.com/resource/pubmed/id/1327724

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1992-11-13
pubmed:abstractText
Cobalt (Co), nickel (Ni), manganese (Mn), cadmium (Cd), and lanthanum (La) are commonly used as calcium (Ca) channel blockers, but some of them, besides reducing Ca entry, also traverse Ca channels and can exert effects intracellularly that confound interpretation of functional responses. Because of this and our need to use Ca channel blockers in an ongoing analysis of Ca channel activity in the regulation of the cytosolic free Ca concentration ([Ca2+]i) and secretion in melanotrophs, we assessed whether the cations mentioned enter these cells. This was done by incorporating the fluorescence for changes that would signal the presence of the cations in the cytosol. In cell-free solution, where the probe and cations can interact freely, Mn, Co, and Ni all quench fluorescence, whereas Cd and La act in a Ca-like manner. When tested on fura-2-loaded melanotrophs in basal (unstimulated) conditions, Mn, Co, and Cd each yielded corresponding signals, thereby showing that they had penetrated the cells. By contrast, Ni caused no quenching of fluorescence even in melanotrophs exposed to 100 mM K+ to recruit additional Ca channels. Ni, therefore, did not penetrate the cells. However, as expected, Ni quenched fluorescence when given artificial access to the cytoplasm by ionomycin. Ni blocked spontaneous entry of Mn, Co, and Cd. It also lowered [Ca2+]i in unstimulated melanotrophs, consistent with blockade of spontaneous Ca entry. Like Ni, La lowered basal [Ca2+]i in unstimulated melanotrophs without penetrating the cells; however, unlike Ni, it penetrated when the melanotrophs were exposed to high potassium. We conclude that Ni is the most specific of the Ca channel blockers tested and that results obtained with Mn, Co, Cd, and La must be interpreted with reserve.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0013-7227
pubmed:author
pubmed:issnType
Print
pubmed:volume
131
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1936-41
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Calcium channels in rat melanotrophs are permeable to manganese, cobalt, cadmium, and lanthanum, but not to nickel: evidence provided by fluorescence changes in fura-2-loaded cells.
pubmed:affiliation
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06510.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.