Excitation by Odorants of Olfactory Receptor Cells: Molecular Interaction at the Ciliary Membrane.

摘要

The first physiological measurements of the response of the olfactory epithelium to odorants were published in 1956 by Ottoson, who introduced the 'electro-olfactogram' (EOG), a negative-voltage transient that can be recorded from the epithelium after odor application. The EOG is believed to result from the summated activity of individual olfactory neurons. Prolonged application of odorant results in the appearance of a transient response, followed by a steady-state potential, the 'tonic' response. Initial characterization of the EOG showed that it could be obtained only from olfactory and not from respiratory epithelium, that the amplitudes of both the phasic and the tonic responses were dependent on the concentration of odorant, and that the EOG was abolished after zinc sulfate lesions of the olfactory epithelium or removal of olfactory cilia by treatment with Triton X-100. Further studies on the EOG indicated that sodium and potassium are the main ions carrying the currents and that calcium is essential for generation of the EOG. In this chapter, we examine these parameters at the molecular level and describe how odorant-sensitive ion channel, cAMP, and calcium may act in concert to mediate and regulate excitation of olfactory receptor neurons by odorants. Reprints. (KT)