Figure 7.

Effect of hypertonic mannitol on the CT response to CO₂ and HCl. (A) The CT responses to dissolved CO₂ (72 mM KHCO₃ + 10%/90% CO₂/O₂; pH 7.4) were recorded relative to the rinse solution, R (72 mM KCl + 10 mM HEPES; pH 7.4). In the second part of the experiment the CT responses were recorded with both rinse (R+M) and the CO₂ solution (M+CO₂) containing, in addition, 1 M mannitol (M). (B) Inset shows a set of transient phasic responses to CO₂ stimulation in the presence and absence of mannitol in an extended time scale. The magnitude of the peak phasic response was normalized to the phasic response elicited by stimulation with 300 mM NH₄Cl. (C) The CT responses to 20 mM HCl + 10 mM KCl (R+HCl) were recorded relative to the rinse solution, R (10 mM KCl). In the second part of the experiment the CT responses were recorded with both rinse (R+M) and the HCl solution (R+M+HCl) containing, in addition, 1 M mannitol (M). The arrows indicate the time when the tongue was superfused with different solutions.