Referenced in: none

Automatically associated channels: Kir6.1 , Kir6.2

Title: Pharmacological and molecular characterization of ATP-sensitive K+ channels in the TE671 human medulloblastoma cell line.

Authors: T R Miller, R D Taber, E J Molinari, K L Whiteaker, L M Monteggia, V E Scott, J D Brioni, J P Sullivan, M Gopalakrishnan

Journal, date & volume: Eur. J. Pharmacol., 1999 Apr 9 , 370, 179-85

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/10323267

Abstract
ATP-sensitive K+ (K(ATP)) channels in the human medulloblastoma TE671 cell line were characterized by membrane potential assays utilizing a potentiometric fluorescent probe, bis-(1,3-dibutylbarbituric acid)trimethine oxonol (DiBAC4(3)), and by mRNA analysis. Membrane potential assays showed concentration-dependent and glyburide-sensitive changes in fluorescence upon addition of (-)-cromakalim, pinacidil, diazoxide and P1075. The rank order of potency for these openers was P1075 > (-)-cromakalim approximately = pinacidil > diazoxide. Additionally, glyburide and glipizide inhibited P1075-evoked responses in TE671 cells with half-maximal inhibitory concentrations of 0.22 and 14 microM, respectively. The rank order potencies of both openers and inhibitors were similar to those observed in the rat smooth muscle A-10 cell line. In contrast, in the rat pancreatic insulinoma RIN-m5F cell line, only diazoxide was effective as an opener. Reverse transcription-polymerase chain reaction (RT-PCR) studies detected sulfonylurea receptors SUR2B and SUR1 mRNA in TE671 cells whereas only SUR2B and SUR1 mRNA were, respectively, detected in A-10 and RIN-m5F cells. The inward rectifier Kir6.2 mRNA was detected in all three cell types whereas Kir6.1 was detected only in A-10 cells. Collectively, the molecular and pharmacologic studies suggest that K(ATP) channels endogenously expressed in TE671 medulloblastoma resemble those present in the smooth muscle.