| Abstract: | Osmotic effects onsalt taste were studied by recording from the rat chorda tympani (CT)nerve and by measuring changes in cell volume of isolated rat fungiformtaste receptor cells (TRCs). Mannitol, cellobiose, urea, or DMSO didnot induce CT responses. However, the steady-state CT responses to 150 mM NaCl were significantly increased when the stimulus solutions alsocontained 300 mM mannitol or cellobiose, but not 600 mM urea or DMSO.The enhanced CT responses to NaCl were reversed when the saccharideswere removed and were completely blocked by addition of 100 µMamiloride to the stimulus solution. Exposure of TRCs to hyperosmoticsolutions of mannitol or cellobiose induced a rapid and sustaineddecrease in cell volume that was completely reversible, whereasexposure to hypertonic urea or DMSO did not induce sustained reductionsin cell volume. These data suggest that the osmolyte-induced increasein the CT response to NaCl involves a sustained decrease in TRC volumeand the activation of amiloride-sensitive apicalNa+ channels. |
