title: Hypoxic stress induces transient receptor potential melastatin 2 (TRPM2) channel expression in adult rat cardiac fibroblasts.
abstract: When cardiac tissue is exposed to hypoxia, myocytes are damaged, while fibroblasts are activated. However, it is unknown what changes are induced by hypoxia in cardiac fibroblasts. In this study, using the whole cell patch-clamp technique, we investigated the effect of hypoxia on membrane currents in fibroblasts primarily cultured from adult rat hearts. Cardiac fibroblasts were incubated for 24 h under normoxic or hypoxic conditions using Anaeropack. Hypoxia increased a current which reversed at around -20 mV in the cardiac fibroblasts. This current was inhibited by clotrimazole, which is an inhibitor of transient receptor potential melastatin 2 (TRPM2) channel and intermediate-conductance Ca(2+)-activated K(+) channel (KCa3.1). ADP ribose in the pipette solution enhanced this current. Quantitative RT-PCR revealed that mRNA of TRPM2, but not that of KCa3.1, was increased by hypoxia. RNA interference of TRPM2 prevented the development of the hypoxia-induced current. H(2)O(2), an activator of TRPM2 channel, induced a higher [Ca(2+)](i) elevation in hypoxia-exposed cardiac fibroblasts than that in normoxia-exposed cells. We conclude that hypoxia induces TRPM2 channel expression in adult rat cardiac fibroblasts.
authors.affiliation: Department of Pharmacology, Fukushima Medical University, School of Medicine, Japan. takahashi.kenji@toaeiyo.co.jp
authors.forename: Kenji
authors.initials: K
authors.lastname: Takahashi
authors.forename: Kazuho
authors.initials: K
authors.lastname: Sakamoto
authors.forename: Junko
authors.initials: J
authors.lastname: Kimura
mesh_terms: D000818:Animals; D002118:Calcium; D015687:Cell Hypoxia; D005347:Fibroblasts / Q000378:metabolism*; D005786:Gene Expression Regulation; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008297:Male; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D034622:RNA Interference; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050053:TRPM Cation Channels / Q000378:metabolism*
chemical_list: D050053:TRPM Cation Channels; C557080:Trpm2 protein, rat; D006861:Hydrogen Peroxide; D002118:Calcium