Temperature and amiloride alter taste nerve responses to Na +, K +, and NH 4 + salts in rats

• Published in: Brain research 1997-01, Vol.744 (2), p.309-317
• Main Authors: Lundy, Robert F., Contreras, Robert J.
• Format: Article
• Language: English
• Subjects: Acetates - pharmacology; Adaptation; Amiloride - pharmacology; Amiloride analog; Animals; Chorda tympani nerve; Chorda Tympani Nerve - drug effects; Male; Potassium Acetate - pharmacology; Rats; Rats, Sprague-Dawley; Salts - pharmacology; Sodium Acetate - pharmacology; Taste - drug effects; Temperature; Transduction
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/S0006-8993(96)01118-3

The effects of adaptation/stimulus temperature (25°C vs. 35°C) on taste nerve responses to salt stimulation and amiloride suppression were assessed in rats. We measured the integrated responses of the chorda tympani nerve to 500 mM concentrations of NaCl, Na 2SO 4, sodium acetate (NaAc), KCl, K 2SO 4, potassium acetate (KAc), NH 4Cl, (NH 4) 2SO 4, and ammonium acetate (NH 4Ac) mixed with or without 100 µ M amiloride hydrochloride at 25°C and 35°C. Taste nerve responses to all Na + and NH + 4 salts, but not K + salts, were significantly smaller at 25°C than at 35°C. Amiloride significantly suppressed taste nerve responses to all salts (Na + salts >K + salts > NH 4 + salts); amiloride suppression of Na + and NH + 4 salts was significantly greater at 25°C than at 35°C. Benzamil-HCl, a more potent Na + channel blocker compared to amiloride, strongly suppressed taste nerve responses to NaCl and KCl, but not to NH 4Cl. Amiloride and benzamil suppression of NaCl responses were similar; however, amiloride suppressed KCl responses more than did benzamil. The results suggest that: (1) amiloride-sensitive Na + channels are involved to varying degrees in the transduction of sodium and potassium salt taste, and (2) amiloride may inhibit membrane proteins other than passive Na + channels during stimulation with potassium and ammonium salts.