The chemistry of olfactory reception: stimulus-specific protection from sulfhydryl reagent inhibition

The group-specific protein reagent, N-ethylmaleimide, irreversibly blocks the electrical response of the olfactory receptor organ of the frog to odorous stimuli. If the odorous substance, ethyl n-butyrate, in concentrations high enough to saturate the receptor system, is present in the nasal cavity before and during a brief exposure to N-ethylmaleimide, the nose, after a wash and a recovery period, responds in nearly normal fashion to vapors of ethyl n-butyrate. Responses to other odorous substances, except those closely related to ethyl n-butyrate, are abolished. We propose that we can use this protection technique to identify the properties of the various receptor sites in the nose, and possibly to characterize the receptor substances.