FIGURE 4.
pH dependence of the acid-evoked [Ca2+]i increases in the circumvallate taste cells. A and B, representative traces of [Ca2+]i changes in response to different pH solutions. pH 5.5 evoked an on response but not an off response, whereas pH 5.0 and pH 4.0 evoked both on and off responses. Cell viability was confirmed by the responses to KCl (50 mm) and ionomycin (5 μm). C, average ratio (340/380 nm) changes for off responses induced by acid solutions at various pH values (6.5, 6.0, 5.5, 5.0, 4.5, or 4.0). Percentage changes were 3.6 ± 0.9, 4.6 ± 1.1, 4.0 ± 1.5, 10.5 ± 2.8, 31.7 ± 4.8, and 39.5 ± 4.1% for pH 6.5, 6, 5.5 5, 4.5, and 4, respectively. Data are shown as mean ± S.E., and values in parentheses indicate the number of cells examined. *, p < 0.05.