The oral sensation of carbonated water: Cross-desensitization by capsaicinand potentiation by amiloride

The oral sensation elicited by carbonated water is reduced by capsaicin and by blockers of carbonic anhydrase. We have investigated the temporal profi le of this sensation and its cross-desensitization by capsaicin. We additio nally tested if the sensation is influenced by amiloride. Following pretrea tment of half of the dorsal tongue with 33 p.p.m. capsaicin, carbonated wat er was flowed over the tongue bilaterally for 5, 15 or 60 s. Subjects then performed a two-alternative forced choice test by indicating which side of the tongue had a stronger sensation and separately rated the sensory intens ity on each side. Capsaicin significantly reduced the intensity of sensatio n elicited by carbonated water, consistent with cross-desensitization. This effect was weaker at 60 s because of a significant decline (desensitizatio n) in ratings of the intensity of carbonated water on both sides of the ton gue. Pretreatment with amiloride resulted in a small but significant increa se in the intensity of the sensation elicited by the 15 s carbonated water stimulus, suggesting an amiloride-sensitive transduction mechanism.