Response of Olfactory Receptor Cells, Isolated and in Situ, to Low Concentrations of Odorants

Abstract

To study vertebrate olfactory receptor neurons by patch clamp methods, the cells are often dissociated from the mucosa and kept in isolation during stimulation with odorants dissolved in the bathing solution (1,3,4,5,9,10,11,13,15). However, disappointingly large concentrations of odorants are required to stimulate such cells, if they can be stimulated at all. Using a similar method with frog olfactory cells, we noted that somewhat better odorant responses were obtained if proteolytic enzymes were not used during cell isolation (while the Ca concentrations was kept at 1–5 μM), and if the cells patched were not attached to the bottom of the chamber but freely moving — by means of their sensory cilia — in the bathing solution. The bath concentration of cineole had to be in the order of 500 nanomolar to elicit a response (5). This seemed a reasonable concentration because most published responses, recorded from olfactory nerve fibers, required even larger (micromolar) concentrations of odorants in the mucosal compartment (see Table 3 of ref. 5).