Chem. Senses 26: 965-969,
2001
© Oxford University Press 2001
Amiloride Blocks Salt Taste Transduction of the Glossopharyngeal Nerve in Metamorphosed Salamanders
Department of Physiology, Teikyo University School of Medicine, Tokyo 173-8605, Japan 1 Department of Biology and Geoscience, Faculty of Science, Shizuoka University, Shizuoka 422-8529, Japan
Correspondence to be sent to: Takatoshi Nagai, Department of Biology, Keio University School of Medicine, Hiyoshi, Yokohama 223-8521, Japan. e-mail: takatosh{at}hc.cc.keio.ac.jp
Studies in the last two decades have shown that amiloride-sensitive Na+ channels play a role in NaCl transduction in rat taste receptors. However, this role is not readily generalized for salt taste transduction in vertebrates, because functional expression of these channels varies across species and also in development in a species. Glossopharyngeal nerve responses to sodium and potassium salts were recorded in larval and metamorphosed salamanders and compared before and after the oral floor was exposed to amiloride, a blocker of Na+ channels known to be responsible for epithelial ion transport. Pre-exposure to amiloride (100 µM) did not affect salt taste responses in both axolotls (Ambystoma mexicanum) and larval Ezo salamanders (Hynobius retardatus). In contrast, in metamorphosed Ezo salamanders the nerve responses to NaCl were significantly reduced by amiloride. In amphibians amiloride-sensitive components in salt taste transduction seem to develop during metamorphosis.