title: Subcellular localization of the delayed rectifier K(+) channels KCNQ1 and ERG1 in the rat heart.
abstract: In the heart, several K(+) channels are responsible for the repolarization of the cardiac action potential, including transient outward and delayed rectifier K(+) currents. In the present study, the cellular and subcellular localization of the two delayed rectifier K(+) channels, KCNQ1 and ether-a-go-go-related gene-1 (ERG1), was investigated in the adult rat heart. Confocal immunofluorescence microscopy of atrial and ventricular cells revealed that whereas KCNQ1 labeling was detected in both the peripheral sarcolemma and a structure transversing the myocytes, ERG1 immunoreactivity was confined to the latter. Immunoelectron microscopy of atrial and ventricular myocytes showed that the ERG1 channel was primarily expressed in the transverse tubular system and its entrance, whereas KCNQ1 was detected in both the peripheral sarcolemma and in the T tubules. Thus, whereas ERG1 displays a very restricted subcellular localization pattern, KCNQ1 is more widely distributed within the cardiac cells. The localization of these K(+) channels to the transverse tubular system close to the Ca(2+) channels renders them with maximal repolarizing effect.
authors.affiliation: Department of Medical Physiology and Copenhagen Heart Research, University of Copenhagen, The Panum Institute, DK-2200 Copenhagen N, Denmark. hannebr@mfi.ku.dk
authors.forename: Hanne Borger
authors.initials: HB
authors.lastname: Rasmussen
authors.forename: Morten
authors.initials: M
authors.lastname: Møller
authors.forename: Hans-Günther
authors.initials: HG
authors.lastname: Knaus
authors.forename: Bo Skaaning
authors.initials: BS
authors.lastname: Jensen
authors.forename: Søren-Peter
authors.initials: SP
authors.lastname: Olesen
authors.forename: Nanna Koschmieder
authors.initials: NK
authors.lastname: Jørgensen
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D019138:Antibodies, Blocking / Q000494:pharmacology; D015153:Blotting, Western; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; D007150:Immunohistochemistry; D051656:KCNQ Potassium Channels; D051657:KCNQ1 Potassium Channel; D018613:Microscopy, Confocal; D016253:Microscopy, Immunoelectron; D009206:Myocardium / Q000378:metabolism* / Q000648:ultrastructure; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D051381:Rats; D012508:Sarcolemma / Q000378:metabolism / Q000648:ultrastructure; D013347:Subcellular Fractions / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D019138:Antibodies, Blocking; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; D051656:KCNQ Potassium Channels; D051657:KCNQ1 Potassium Channel; C496911:Kcnq1 protein, rat; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated