Electrophysiological properties of identified cells in the in vitro olfactory epithelium of the tiger salamander

Abstract

An in vitro preparation of the salamander olfactory epithelium has been developed for electrophysiological analysis. Intracellular measurements of membrane properties of the main epithelial cell types have been carried out, combined with Lucifer Yellow injections. The most prevalent type of cell had a high resting membrane potential and relatively low input resistance. This cell never discharged impulses, either spontaneously or to injected current. Lucifer Yellow injections identified this cell type as a supporting cell. A less frequent type had a medium resting potential and a very high input resistance. This type always discharged impulses in response to injected depolarizing current. Lucifer Yellow injections identified this cell type as an olfactory receptor neuron. The least frequent type had a medium resting potential and a high input resistance. It never generated action potentials. This nonspiking type was tentatively identified as an immature receptor neuron in the process of differentiating from basal stem cells in the epithelium. These are the first results to document physiological properties for the main cell types and morphological identification of two of the types in the same preparation of the olfactory epithelium. Our results support previous suggestions regarding the glial-like properties of the supporting cells. The membrane properties of the receptor neurons appear to be well suited for mediating the olfactory sensory response of these cells.