A chemical-modification approach to the olfactory code.

A photoaffinity labeling technique was used to study the receptors involved in the discrimination of odorants. Aromatic azides, 1-azidonaphthalene (AzN) and 1-azido-4-nitronaphthalene (AsNN), were found to be pleasant-smelling compounds and produced good responses, giving standard EOG's (electro-olfactogram) of the kind observed for normal odorants. Following irradiation of the frog olfactory mucosa with light during constant stimulation with one of the azides vapor, there was a specific partial inhibition of the receptors for that odorant. The extent of reduction in amplitude of the EOG responses to AzN and AzNN varied between 40 to 60% of the original amplitude.