Effects of chemical modifiers on taste responses in the rat chorda tympani.

1. Effects of chemical modifiers : p-chloromercuric benzoate (PCMB) ; N-ethylmaleimide (NEM) ; iodoacetic acid (IAA) ; 5,5-dithiobis-2-nitrobenzoate (DTNB) ; and dinitrofiuorobenzene (FDNB), and of metabolic inhibitors : NaCN; and 2,4-dinitrophenol (DNP) on taste responses in the chorda tympani of rats were studied. 2. PCMB, NEM, and IAA at optimum concentrations depressed the sucrose response selectively without producing significant change in responses to the other three basic quality taste stimuli. The depression of the sucrose response was reversibly restored by water rinse. DTNB produced no observable effect. 3. The inhibitory effect of PCMB on the sucrose response was twenty times stronger than that of NEM. 4. The mechanism of the depression of the sucrose response by PCMB and NEM was classified as a type of competitive inhibition. 5. No effect of PCMB or NEM on responses to the four basic quality stimuli was observed when they had been mixed with mercaptoethanol. 6. FDNB depressed responses to NaCl, HCl, and quinine without producing any influence on sucrose responses. 7. The metabolic inhibitors did not depress taste responses.