DIETARY NA-RESTRICTION PREVENTS DEVELOPMENT OF FUNCTIONAL NA+ CHANNELS IN TASTE CELL APICAL MEMBRANES - PROOF BY IN-VIVO MEMBRANE VOLTAGE PERTURBATION()

1. Chorda tympani (CT) neural responses to NaCl were recorded while th e potential across the apical membrane of taste cells was perturbed by voltage clamp in rats fed a Na+-restricted diet pre- and postnatally (Na+-restricted rats) and in controls. 2. Control rats gave CT respons es that were enhanced at negative voltage clamp and suppressed at posi tive voltage clamp. In contrast, CT responses from Na+-restricted rats were virtually voltage insensitive. 3. Analysis of the voltage-sensit ivity of the CT response shows that Na+-restricted rats have <10% of t he density of functional apical Na+ channels normally present in contr ol rats demonstrating that early dietary Na+-restriction prevents the functional expression of these key elements in salt taste transduction . Furthermore, the data demonstrate the value of this technique in ass essing involvement of distinct cellular domains in taste transduction.