Voltage-gated delayed rectifier <tex>K_{v}1$</tex>-subunits may serve as distinctive markers for enteroglial cells with different phenotypes in the murine ileum

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 preparations 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 neurons 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 support 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.