| Abstract: | In order to study the role of peripheral taste sensitivity inmediating increases in salt intake of the rat, the effects ofsodium deprivation and adrenalectomy on chorda tympani nerveresponses to taste stimulation were determined. Sodium deprivationresulted in a reduction in whole nerve responsivity to suprathresholdNaCl concentrations requiring a 10-fold increase in concentrationto elicit the same neural signal of control preparations. Saltintake of sodium deprived rats was predicted by adjusting datain a 10-min intake test from control rats for the reduced neuralsignal and lower salivary sodium levels of sodium deprived rats.The whole nerve responses to LiCl and KCl, as well as to NaCl,were reduced after sodium deprivation and adrenalectomy. Themultifiber response of the chorda tympani is comprised of theindividual responses of NaCl sensitive N-best fibers and HCl/NaClsensitive H-best fibers. After sodium deprivation N-best fibers'responses to suprathreshold concentrations of NaCl were reduced;H-best fibers' responses were not affected by sodium deprivation.Future studies will determine the effect of KCl and other saltson responses of N-best and H-best fibers. Applying Beidler'sbiophysical model to the single fiber data suggests that sodiumdeprivation influences receptor mechanisms for NaCl of N-bestfibers and not H-best fibers. Because repeated NaCl stimulationresulted in increased chorda tympani responsivity to NaCl, wesuggest that sodium deprivation may alter the salt receptorsimply by disuse. Altered receptor sensitivity may be an adaptivemechanism to influence salt consumption by a shift in suprathresholdNaCl intensity. |
