Neuroscience Letters 461 (2009) 80–84 Contents lists available at ScienceDirect Neuroscience Letters journal homepage: www.elsevier.com/locate/neulet Voltage-gated delayed rectifier K v 1-subunits may serve as distinctive markers for enteroglial cells with different phenotypes in the murine ileum Anna Costagliola a , Luc Van Nassauw b,c , Dirk Snyders d , Dirk Adriaensen b , Jean-Pierre Timmermans b,∗ a Department of Structures, Functions and Biological Technology, University of Naples Federico II, Via F. Delpino 1, 80137 Napoli, Italy b Laboratory of Cell Biology and Histology, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium c Laboratory of Human Anatomy and Embryology, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium d Laboratory of Molecular Biophysics, Physiology and Pharmacology, University of Antwerp, Universiteitsplein 1, 2610 Antwerpen, Belgium article info Article history: Received 10 April 2009 Received in revised form 13 June 2009 Accepted 17 June 2009 Keywords: Voltage-gated potassium channels Kv1.1 Kv1.2 Ileum Enteroglial cells Mouse abstract Due to entangled results concerning K v 1 subunit distribution in the gastrointestinal wall, we aimed to unravel the expression of the delayed rectifier potassium subunits K v 1.1 and K v 1.2 in the murine ileum. Presence and distribution of both subunits were determined in cryosections and whole-mount prepa- rations of the ileum of three different murine strains by indirect immunofluorescence, and analysed by conventional fluorescence and confocal microscopy. Distribution of both subunits was similar in the ileum of the three strains. K v 1.1 immunoreactivity (IR) was found in some S100-expressing enteroglial cells (EGC) located at the periphery of myenteric ganglia, in S100-positive EGC along interganglionic, intramuscular and vascular nerve fibres, and in S100-positive EGC of the submucous plexus. K v 1.1 IR was also observed in some GFAP-expressing EGC at the periphery of myenteric ganglia, and in GFAP-positive EGC of submucous ganglia. K v 1.2 IR was detected in some intramuscular S100-positive EGC, in almost all submucous S100-expressing EGC, and in a few GFAP-expressing EGC. K v 1.2 IR was also expressed in a majority of enteric neurons. Coding of these neurons showed that all cholinergic and most nitrergic neu- rons express K v 1.2. In conclusion, the results showed that K v 1.1 and K v 1.2 were predominantly expressed in distinct EGC phenotypes. K v 1.2 was also observed in distinct neuron subpopulations. Our results sup- port the active role of EGC with distinct phenotypes in intestinal functions, which is relevant in view of their modulating role on intestinal barrier and inflammatory responses. © 2009 Elsevier Ireland Ltd. All rights reserved. Potassium (K + ) channels are the largest and most diverse group of ion channels, and regulate a wide range of cellular functions. They are assembled from pore-forming  subunits which may be associated with auxiliary  subunits. Cloning and sequencing revealed that most K + channel subunits are members of two dis- tantly related superfamilies encoding either voltage-gated (K v ) or inwardly rectifying (K ir ) channel subunits. At least 11 subfamilies of K v channel  subunits (K v 1–11) have been described in mam- mals and are widely expressed in both excitable and non-excitable cells. K v channels play important roles in the regulation of cellu- lar excitability, in synaptic transmission and in setting the resting membrane potentials. Of all K v channels, the group of tetrameric K v 1 or Shaker-related delayed rectifier K + channel  subunits has been investigated most extensively [13,18]. All members of this family have been found to co-assemble into functional tetrameric ∗ Corresponding author at: Laboratory of Cell Biology and Histology, Depart- ment of Veterinary Sciences, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium. Tel.: +32 3 265 33 00; fax: +32 3 265 33 01. E-mail address: jean-pierre.timmermans@ua.ac.be (J.-P. Timmermans). channels resulting in an increased diversity of K v 1 channels [21]. In the mammalian brain, K v 1 channels are mainly found as het- erotetrameric complexes with K v 1.1 and K v 1.2 as the predominant partners [23]. Voltage clamp studies of isolated smooth muscle cells of the murine, cat and rabbit intestine and of the guinea-pig gastric antrum have recorded several types of voltage-sensitive ion cur- rents including delayed rectifier K + currents [2,7,24,29,30]. Other studies revealed that neurons and enteroglial cells (EGC) in isolated myenteric ganglia of the guinea-pig also display several types of voltage-sensitive ion channels, including delayed rectifier K + chan- nels [4,14,49]. Pharmacological experiments in guinea-pig ileum revealed that K v 1.1 subunits are expressed in the enteric nervous system (ENS) where they modulate excitation–contraction cou- pling [38,45,46], while another study has reported on the presence of K v 1.1 in enteric neurons and interstitial cells of Cajal (ICC) in gastrointestinal (GI) tissues of the dog, guinea-pig and mouse [17]. In man, K v 1.1 mRNA was detected in GI stromal tumours derived from ICC [9], while a recent study in man and mouse demon- strated both K v 1.1 and K v 1.2 in enteric ganglia [20].K v 1.1 was found to be expressed in intestinal epithelial cells in mouse, rat, rabbit 0304-3940/$ – see front matter © 2009 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.neulet.2009.06.053