Proton currents through amiloride-sensitive Na + channels in isolated hamster taste cells: Enhancement by vasopressin and cAMP

• Published in: Neuron (Cambridge, Mass.) Vol. 10; no. 5; pp. 931 - 942
• Main Authors: Gilbertson, Timothy A., Roper, Stephen D., Kinnamon, Sue C.
• Format: Journal Article
• Language: English
• Published: Cambridge, MA Elsevier Inc 01.05.1993; Cell Press
• Subjects: 8-Bromo Cyclic Adenosine Monophosphate - pharmacology; Amiloride - pharmacology; Animals; Arginine Vasopressin - pharmacology; Biological and medical sciences; Cricetinae; Cyclic AMP - pharmacology; Electric Conductivity; Fundamental and applied biological sciences. Psychology; Hydrogen-Ion Concentration; Olfactory system and olfaction. Gustatory system and gustation; Protons; Signal Transduction; Sodium Channels - drug effects; Sodium Channels - physiology; Taste Buds - physiology; Vasopressins - pharmacology; Vertebrates: nervous system and sense organs; Rodentia; Electrophysiology; Cyclic AMP; Patch clamp method; Ionic channel; Ionic current; Taste bud; Vasopressin; Vertebrata; Mammalia; Sodium; Proton; Hamster
• ISSN: 0896-6273; 1097-4199
• DOI: 10.1016/0896-6273(93)90208-9

Amiloride has been suggested to inhibit responses to a variety of taste stimuli, including salty, sweet, and sour (acid). To test for the involvement of amiloride-sensitive Na + channels in the transduction of acid stimuli, fungi-form taste receptor cells were examined using patch-clamp techniques. Approximately one-half of all cells had amiloride-sensitive Na + currents (I Na) with a K i value near 0.2 μM amiloride. After blocking voltage-gated conductances, cells having amiloride sensitivity were tested for responses to acid stimuli. Over three-fourths of cells showed an inward proton current (I H + ) with an extrapolated reversal potential near approximately +150 mV, which was completely blocked by amiloride (30 μM). Treatment of isolated taste cells with argininee-vasopressin caused equivalent increases in both I Na and I H + ; each effect was mimicked by 8-Br-cAMP. Taken together, these results indicate that protons permeate amiloride-sensitive Na + channels in hamster fungiform taste cells and contribute to acid transduction.