Title: Endogenous TRPM4-like channel in Chinese hamster ovary (CHO) cells.

Authors: Oleg V Yarishkin, Eun-Mi Hwang, Jae-Yong Park, Dawon Kang, Jaehee Han, Seong-Geun Hong

Journal, date & volume: Biochem. Biophys. Res. Commun., 2008 May 2 , 369, 712-7

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/18307979

Abstract
Chinese hamster ovary (CHO) cells used in many transfection studies have been found to endogenously express channels permeable to monovalent cations, but not to divalent cations. In the presence of intracellular Ca(2+), 23-pS channel with a linear current-voltage (I-V) relationship could be frequently observed in inside-out patches but not in cell-attached patches. The open probability was voltage-dependent, which is higher at positive potentials. The channel was dose-dependently activated by relatively high level of Ca(2+) (EC(50)=1.04+/-0.08 mM), and sensitively inhibited by 100 microM ATP, ADP, AMP, and 1mM spermine. However, ruthenium red (2 microM) had no effect. Reverse transcript polymerase chain reaction (RT-PCR) supported the presence of mRNA encoding TRPM4b channel protein. Western blot assay finally confirmed the presence of this channel protein in membrane fraction of CHO cells. These results provide evidence that CHO cells express an endogenous TRPM4b-like channel, and thereby can be used as a tool to study de novo regulation/modulation of TRPM4 channel.