Referenced in: none

Automatically associated channels: Kir6.1 , Kir6.2

Title: Characterisation of sulphonylurea and ATP-regulated K+ channels in rat pancreatic A-cells.

Authors: K Bokvist, H L Olsen, M Høy, C F Gotfredsen, W F Holmes, K Buschard, P Rorsman, J Gromada

Journal, date & volume: Pflugers Arch., 1999 Sep , 438, 428-36

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/10519134

Abstract
We have monitored whole-cell and single channel ATP-sensitive K+ (KATP) currents in isolated rat glucagon-secreting pancreatic A-cells. Tolbutamide produced a concentration-dependent decrease in the whole-cell KATP conductance (Ki = 6 microM) and initiated action potential firing. The K+ channel opener diazoxide, but not cromakalim or pinacidil, inhibited electrical activity and increased the whole-cell K+ conductance fourfold. ATP applied to the intracellular face of the membrane inhibited KATP channel activity with a Ki of 17 microM, an effect that could be counteracted by Mg-ADP and Mg-GDP. GTP and UTP did not affect KATP channel activity. Phosphatidylinositol 4,5-bisphosphate activated KATP channels inhibited by ATP after a delay of 90 s. In situ hybridisation demonstrated the expression of the mRNA encoding KATP channel subunits Kir6.2 and SUR1 but not Kir6.1 and SUR2. We conclude that rat pancreatic A-cells express KATP channels with the nucleotide-, sulphonylurea- and K+ channel-opener sensitivities expected for a channel formed by Kir6.2 and SUR1 subunits.