Linked Life Data

2090953

Source:http://linkedlifedata.com/resource/pubmed/id/2090953

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
1991-6-3
pubmed:abstractText
The patch-clamp technique was used to examine the tolbutamide-sensitivity of the adenosine 5'-triphosphate (ATP)-dependent K+ channel in mouse pancreatic B-cells. When studied at 37 degrees C in cell-attached membrane patches, this channel had a single-channel conductance of 88 pS and was half-maximally inhibited by 2.2 mumol/l tolbutamide in the presence of 3 mmol/l D-glucose and 10 mumol/l nifedipine. The tolbutamide-induced decrease in the amplitude of the single-channel currents indicated that the membrane potential was sufficiently depolarized for initiation of insulin release by 30 but not by 10 mumol/l of tolbutamide. Using 300 mumol/l diazoxide to open the ATP-dependent K+ channels already closed by 3 mmol/l D-glucose alone, it was demonstrated that initiation of insulin release requires closure of more than 98% of all ATP-dependent K+ channels. In excised inside-out membrane patches, the K+ channel-blocking potency of tolbutamide was maximally enhanced by 0.3 mmol/l adenosine 5'-diphosphate (ADP) at the cytoplasmic side. This ADP effect required the presence of Mg2+. Inhibition of K+ channel activity by ATP, ADP (Mg2(+)-free) or their non-hydrolyzable analogues adenylyl-imidodiphosphate (AMP-PNP) and alpha, beta methylene adenosine 5'-diphosphate (AMP-CP) was not accompanied by enhancement of tolbutamide-sensitivity. The results suggest that cytosolic MgADP controls tolbutamide-sensitivity by interaction with a receptor site not identical with the site mediating channel closure and that this control plays a role in the intact B-cell.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0028-1298
pubmed:author
pubmed:issnType
Print
pubmed:volume
342
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
566-74
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
1990
pubmed:articleTitle
Tolbutamide-sensitivity of the adenosine 5'-triphosphate-dependent K+ channel in mouse pancreatic B-cells.
pubmed:affiliation
Institut für Pharmakologie und Toxikologie, Universität Göttingen, Federal Republic of Germany.
pubmed:publicationType
Journal Article, In Vitro, Research Support, Non-U.S. Gov't