Responsiveness of olfactory neurons to distinct aliphatic aldehydes.

The responsiveness of isolated olfactory sensory neurons to stimulation with aliphatic aldehydes of varying chain length (5-10 hydrogenated carbon atoms) was investigated by means of Ca(2+ )imaging. More than half the cells examined were responsive to aliphatic aldehydes. Individual cells did not react or reacted to one or multiple aldehydes; in the latter case, cells only reacted to aldehydes of consecutive carbon chain lengths. The largest proportion of cells responded to octanal. It was also demonstrated that a structural difference as small as one hydrogenated carbon atom was detectable by the olfactory neurons. Neurons were increasingly able to discriminate between two aldehydes as the difference in chain length between the two increased. Discrimination between aldehydes with longer carbon chains was reduced. Although the odorants examined belong to a distinct chemical class and differ only slightly in structure, individual olfactory sensory neurons showed quite different receptive properties.