Linked Life Data

9033963

Source:http://linkedlifedata.com/resource/pubmed/id/9033963

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1997-6-4
pubmed:abstractText
The prolonged exposure of pancreatic islets and isolated beta cells to elevated glucose concentrations induces a state of unresponsiveness to glucose (desensitization). However, an increased sensitivity to glucose (detected by a shift to the left of the dose-response curve of glucose-induced insulin release) has been also reported after chronic exposure to glucose, making the overall response less comprehensible. In vitro models have many theoretical and practical advantages in better understanding the effects of the prolonged glucose stimulation; moreover, they are also suitable for studying the mechanisms responsible of the observed alterations. We have performed a time-course study of the effect of the exposure to glucose at high concentration on the secretory behaviour of beta cells. Rat pancreatic islets exposed for 30 min to high glucose (300 mg/dl) showed increased basal insulin secretion (175 +/- 29 vs 44 +/- 8 pg/islet (per 30 min; n = 5, P < 0.002) was the only difference from control islets (exposed to 100 mg/dl). After 3 h exposure to high glucose, also increased sensitivity to glucose was observed, as indicated by a shift to the left of the glucose dose-response curve (EC50 123 +/- 10 and 177 +/- 11 mg/dl, respectively; n = 5, P < 0.05). After 6 h exposure to high glucose, besides the two alterations already described, also a decrease in glucose-induced insulin release was observed (688 +/- 104 vs 1184 +/- 34 pg/islet per 30 min; n = 5, P < 0.01). We studied the mechanism responsible for these alterations and we found that the "supersensitivity" to glucose may be related to alterations in the "glucose-sensing" mechanism of beta cells, in particular in glucose phosphorylation. In contrast, in islets desensitized to glucose our data suggest that ion flux and consequent membrane potential changes play a key role in determining the secretory defect. Since a normal response to glyburide was observed, a proximal signal defect for closure of potassium channels is more likely than an intrinsic defect in the channel. In conclusion, our data show what the prolonged stimulation of beta cells with glucose at high concentration induces a series of distinct secretory abnormalities, with a pattern of response that leads first to increased sensitivity and then to decreased responsiveness to glucose.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0940-5429
pubmed:author
pubmed:issnType
Print
pubmed:volume
33
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
253-6
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
Effects of prolonged glucose stimulation on pancreatic beta cells: from increased sensitivity to desensitization.
pubmed:affiliation
Institute of Internal Medicine, Endocrinology and Metabolism, University of Catania, Ospedale Garibaldi, Italy.
pubmed:publicationType
Journal Article, Review