The effects of temperature on gustatory response of rats

Abstract

Abstract Impulse discharges in the chorda tympani nerve of rats to stimulation of the tongue by NaCl, KCl, CaCl 2 , HCl, quinine and sucrose at varying temperatures were recorded using an integrator. The tongue had been preadapted to temperature of stimulating solutions so as to eliminate thermal response. The magnitude of response to all kinds of stimuli except for sodium salts of 0.01 to 0.03 M was increased with a rise in temperature from 10° to 30°C and declined from 30° to 45°C, indicating the greatest magnitude at about 30°C. The response magnitude for 0.01 M NaCl was decreased with a rise in temperature from 10° to 45°C. The threshold for NaCl rises with a rise in temperature. Q 10 values for the magnitude of response to 0.03 M to 1.0 M NaCl, KCl, CaCl 2 , HCl, quinine and sucrose are less than two between 10° and 30°C, −1.1 to −1.9 between 30° to 40°C and −1.8 to −3.4 between 35° and 45°C. Sucrose, HCl and quinine gave greater Q 10 values than did NaCl, KCl and CaCl 2 . From such small Q 10 values it has been concluded that the reaction between taste receptors and stimuli, which ultimately leads to initiation of gustatory impulses, is of physical nature rather than enzymatic one.