Ossebaard C A, Smith D V
Department of Anatomy, University of Maryland School of Medicine, Baltimore 21201-1509, USA.
Physiol Behav. 1996 Nov;60(5):1317-22. doi: 10.1016/s0031-9384(96)00258-2.
The transduction of Na+ salts in many species is mediated by both apical and submucosal ion channels on the taste receptor-cell membrane. The apical ion channel is blockable by the diuretic amiloride, whereas the submucosal pathway is not. Previous human psychophysical studies have shown a decrease in NaCl taste intensity caused by amiloride that is smaller than the reduction of the electrophysiological response produced by amiloride in other species. Many salts, including NaCl, elicit not only a salty taste to humans, but also sweet, sour, or bitter side tastes. Amiloride has been shown to reduce the sourness, but not the saltiness, of NaCl and Na gluconate and to have no effect on the taste of KCl. The present experiment further evaluated the hypothesis that the sour taste of Na+ and Li+ salts is mediated by the amiloride-sensitive transduction mechanism, by examining the effect of amiloride on the taste of LiCl, which is considerably more sour than NaCl. Four concentrations of NaCl, LiCl, and KCl were presented to the anterior tongue following adaptation to water or after 10 microM amiloride treatment. Subjects estimated the intensity of the taste of each stimulus and divided this estimate among the appropriate taste qualities. There was a significant decrease in the total taste intensity of NaCl and LiCl after amiloride, but no effect on KCl; LiCl was more greatly suppressed than NaCl. These data show no effect on the saltiness of LiCl or NaCl, except for a small reduction in the saltiness of 0.1 M NaCl. On the contrary, there was a significant effect on the sourness of both NaCl and LiCl. Citric acid (3.2 mM) was also used as a stimulus, but amiloride treatment had no effect on its sourness. These data indicate that the amiloride-sensitive channel plays a key role in the perception of the sour taste of NaCl and LiCl (but not citric acid) and little role in the perception of saltiness. The salty taste of these salts may arise from other transduction pathways.
在许多物种中，Na⁺盐的转导是由味觉受体细胞膜上的顶端和黏膜下离子通道介导的。顶端离子通道可被利尿药氨氯吡脒阻断，而黏膜下途径则不会。先前的人体心理物理学研究表明，氨氯吡脒导致的NaCl味觉强度降低幅度小于其在其他物种中产生的电生理反应降低幅度。许多盐类，包括NaCl，不仅会给人类带来咸味，还会带来甜、酸或苦等其他味道。研究表明，氨氯吡脒可降低NaCl和葡萄糖酸钠的酸味，但不影响其咸味，且对KCl的味道没有影响。本实验通过研究氨氯吡脒对LiCl味道的影响，进一步评估了Na⁺和Li⁺盐的酸味是由氨氯吡脒敏感的转导机制介导的这一假设，LiCl的酸味比NaCl强得多。在适应水或接受10 microM氨氯吡脒处理后，将四种浓度的NaCl、LiCl和KCl呈现给舌头前部。受试者估计每种刺激的味觉强度，并将该估计值分配到相应的味觉特性中。氨氯吡脒处理后，NaCl和LiCl的总味觉强度显著降低，但对KCl没有影响；LiCl比NaCl受到的抑制作用更大。这些数据表明，除了0.1 M NaCl的咸味略有降低外，对LiCl或NaCl的咸味没有影响。相反，对NaCl和LiCl的酸味都有显著影响。柠檬酸（3.2 mM）也用作刺激物，但氨氯吡脒处理对其酸味没有影响。这些数据表明，氨氯吡脒敏感通道在NaCl和LiCl（而非柠檬酸）酸味的感知中起关键作用，而在咸味感知中作用很小。这些盐类的咸味可能来自其他转导途径。
