Activation of voltage-sensitive Ca2+ currents by vasopressin in an insulin-secreting cell line

Thorn, P. and Petersen, O. H. (1991) Activation of voltage-sensitive Ca2+ currents by vasopressin in an insulin-secreting cell line. Journal of Membrane Biology, 124 1: 63-71.


Author Thorn, P.
Petersen, O. H.
Title Activation of voltage-sensitive Ca2+ currents by vasopressin in an insulin-secreting cell line
Journal name Journal of Membrane Biology
Publication date 1991-10
Sub-type Article
DOI 10.1007/BF01871365
Volume number 124
Issue number 1
ISSN 0022-2631 (Print); 1432-1424 (Online)
Start page 63
End page 71
Total pages 8
Place of publication New York
Publisher Springer
Language eng
Subject 320300 Medical Biochemistry and Clinical Chemistry
Abstract The effect of vasopressin on voltage-sensitive Ca2+ currents in the rat insulinoma cell line RINm5F has been investigated in patch-clamp whole-cell and single-channel current recording experiments. In the whole-cell recording configuration the dominant inward current in the presence of tetrodotoxin was noninactivating and had a high voltage threshold. This current was much enhanced when external Ca2+ was replaced by Ba2+ and was blocked by 1 mgrm nifedipine. It can therefore be classified as an L-current. Vasopressin enhanced the L-current without changing the voltage threshold of activation or the voltage at which the peak current was observed. Vasopressin effects were seen at concentrations as low as 0.01nm, and the maximal effect was observed at about 1nm. In higher concentrations the vasopressin effects were weaker, with effects at 50nm of about the same magnitude as at 0.01nm. In single-channel current recording experiments carried out with the cell-attached configuration there were no effects on single L-channel currents when vasopressin was added to the bath solution, but in experiments in which vasopressin (5nm) was infused into the patch pipette a marked increase in the apparent channel open state probability was observed. We conclude that vasopressin, a peptide that is known to markedly enhance glucose-evoked insulin secretion, stimulates opening of the voltage-sensitive Ca2+ channels in insulin-secreting cells.
Keyword Ca2+ channels
vasopressin
single-channel currents
whole-cell current
insulin secreting cell
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article
Collection: School of Biomedical Sciences Publications
 
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