Salt taste inhibition by cathodal current

• Published in: Brain research bulletin Vol. 80; no. 3; pp. 107 - 115
• Main Authors: Hettinger, Thomas P., Frank, Marion E.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 28.09.2009
• Subjects: Adult; Animals; Anions - pharmacology; Cathode-off; Cathode-on; Cations, Monovalent - pharmacology; Chemoreceptor Cells - drug effects; Chemoreceptor Cells - physiology; Chorda Tympani Nerve - drug effects; Chorda Tympani Nerve - physiology; Cricetinae; Electrodes; Electrophysiology; Female; Human gustation; Humans; Ionic stimulus coding; Male; Neurology; Salts - pharmacology; Signal Processing, Computer-Assisted; Taste - physiology; Taste Buds - drug effects; Taste Buds - physiology; Taste inhibition; Tongue - drug effects; Tongue - physiology; Cathode-off; Human gustation; Cathode-on; Ionic stimulus coding; Taste inhibition
• ISSN: 0361-9230; 1873-2747; 1873-2747
• DOI: 10.1016/j.brainresbull.2009.06.019

Effects of cathodal current, which draws cations away from the tongue and drives anions toward the tongue, depend on the ionic content of electrolytes through which the current is passed. To address the role of cations and anions in human salt tastes, cathodal currents of −40 μA to −80 μA were applied to human subjects’ tongues through supra-threshold salt solutions. The salts were sodium chloride, sodium bromide, potassium chloride, ammonium chloride, calcium chloride, sodium nitrate, sodium sulfate, sodium saccharin, sodium acetate and sodium benzoate, which taken together encompass salty, bitter, sour and sweet taste qualities. The taste of NaCl, the salty and bitter tastes of the other chloride salts and the taste of NaNO 3 was inhibited, suggesting the current displaced stimulatory cations from salty and bitter receptors. However, bitter tastes of non-halide sodium salts were not inhibited, likely because other bitter receptors respond to anions. A discharge current at cathode-off ubiquitously evoked a metallic taste reminiscent of anodal taste used in clinical electrogustometry. Analogous effects on ambient NaCl responses were recorded from the hamster chorda tympani nerve. Increases in tastes of the saccharin and benzoate anions were not evoked during current flow, suggesting that cathodal current does not carry stimulatory anions to sweet receptors. Cathodal current may selectively inhibit salty and bitter– salty tastes for which proximal stimuli are cations.