Effects of Temperature on the Generator and Action Potentials of a Sense Organ

Abstract

Charge transfer through the receptor membrane of the nonmyelinated ending of Pacinian corpuscles is markedly affected by temperature. The rate of rise and the amplitude of the generator potential in response to a constant mechanical stimulus increase with temperature coefficients of 2.5 and 2.0 respectively. The duration of the falling phase, presumably a purely passive component, and the rise time of the generator potential are but little affected by temperature. The following interpretation is offered: Mechanical stimulation causes the conductance of the receptor membrane to increase and ions to flow along their electrochemical gradients. An energy barrier of about 16,000 cal/mole limits the conductance change. The latter increases, thus, steeply with temperature, causing both the rate of rise and the intensity of the generator current to increase.The membrane of the adjacent Ranvier node behaves in a distinctly different manner. The amplitude of the nodal action potential is litt|e changed over a wide range of temperature, while the durations of its rising and failing phases increase markedly. The electrical threshold of the nodal membrane is rather constant between 40 and 12°C. Below 12°C the threshold rises, and the mechanically elicited generator current fails to meet the threshold requirements of the first node. Cold block of nerve impulse initiation then ensues, although the receptor membrane still continues to produce generator potentials in response to mechanical stimulation. I N T R O D U C T I O NMechanical stimulation of the receptor membrane of-Pacinian corpuscles causes transfer of charges. The amount of charges transferred increases with the area of membrane excited (Loewenstein, 1959(Loewenstein, , 1961, and with the electrical gradients across it (Loewenstein and Ishiko, 1960). A plausible mechanism of the charge transfer process is that the mechanical stimulus produces an increase in conductance of the receptor membrane, and that charges move along their gradients through the membrane. This paper deals with an aspect ~o5

The effect of skin temperature on vibrotactile sensitivity

“…This QIO corresponds to an amplitude change of 15 dBa value close to the threshold change observed in the present study for the 250-Hz stimulus between 20°a nd 37°c. z A study by Ishiko and Loewenstein (1961) also investigated the effect of temperature on Pacinian corpuscles, and, though their results were not in complete accord with those of Inman and Peruzzi, they too found that transduction was influenced by temperature. From Ishiko and Loewenstein's Figure 9 (p. 115), it can be seen that the mechanical threshold for production of a nerve impulse increased approximately 11 dB as temperature dropped from 37°to 20°C.…”

Effect of Changes in Finger Skin Temperature on Vibrotactile Perception Threshold

“…The problem of the mechanoreceptor sensitivity depending on temperature changes was reported for the first time in early 1960s. The first study was conducted on the Pacinian corpuscles isolated in cats [4,5]. In 1961, Inman and Peruzzi described the phenomenon of nerve impulse disappearance at the Pacinian corpuscles at temperatures between 15°C and 16.7°C and the generation of numerous impulses on mechanical stimulation at 25°C [6].…”

Structure and innervation of the vibrissal follicle-sinus complex in the Australian water rat,Hydromys chrysogaster

“…Because the sensitivity of cutaneous mechanoreceptors decreases with decreasing skin temperature, which has been shown at the receptor level (Inman and Peruzzi, 1961;Ishiko and Loewenstein, 1961;Necker, 1983) as well as by human psychophysics (Green et al, 1979;Bolanowski et al, 1988), aquatic mammals should have developed appropriate adaptations. This is especially true for a small mammals like the water rat, which has been demonstrated to be a thermally unstable species (Fanning and Dawson, 1980;Dawson and Fanning, 1981).…”