Linked Life Data

7823418

Source:http://linkedlifedata.com/resource/pubmed/id/7823418

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1995-2-16
pubmed:abstractText
The periodic spike-burst response of pancreatic beta-cells varies in duration with an increase of external glucose within the range 5-20 mM. To elucidate the mechanism determining the length of spike-burst, we studied the low-Na+ induced change in electrical response to glucose which is similar to the change induced by high glucose. Cytoplasmic pH (pHi) and Ca2+ concentration ([Ca2+]i) were measured by the microfluorometric method under normal and low-Na+ conditions in mouse pancreatic islets. Lowering external Na+ concentration from 135 to 25 mM by replacing Na+ with Tris+ induced progressive alkalinization in islet cells in the presence of 11.1 mM glucose. In contrast, reduction of external Na+ by replacement with Li+ caused intracellular acidification. Both manipulations described above caused a marked increase in [Ca2+]i, suggesting the presence of Na+/Ca(2+)-antiport activity. Although the change in pHi induced by decreasing external Na+ varied in direction depending on the species of cations used for replacing Na+, the pattern of electrical activity consistently changed from the spike-burst type to the continuous spike-generation type without regard for the difference in species of cations replacing Na+. These findings lead to the following hypothesis: A decrease in Na+ influx could cause a decrease in ATP-consumption by Na+/K(+)-pumps that prevents the fall of intracellular ATP concentration. The resultant continuation of high concentrations of intracellular ATP may be responsible for the abolishment of the silent phase.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0021-521X
pubmed:author
pubmed:issnType
Print
pubmed:volume
44
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
283-93
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Effects of lowering external Na+ concentration on cytoplasmic pH and Ca2+ concentration in mouse pancreatic beta-cells: mechanism of periodicity of spike-bursts.
pubmed:affiliation
Department of Physiology, Shiga University of Medical Science, Ohtsu, Japan.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't