The steady state of heat production of nerve

Abstract

If a frog''s medullated nerve at 20[degree] C be subjected to continued stimulation at low or moderate frequency (up to 50 shocks per sec.) a steady state is reached in 25 to 40 min. at which recovery keeps pace with breakdown and the rate of heat production becomes constant. When the stimulus is discontinued the heat production returns, also in 25 to 40 min., to its "basal" level. At low frequencies the total heat per impulse is of the order of 10~8 calorie per gm. At higher frequencies a steady state is impossible; the rate of heat production reaches a maximum and then declines. During the state of "fatigue" induced by high frequency stimulation a sudden change to a lower frequency may cause an immediate increase in the rate of heat production. The greatest rate of heat production due to steady stimulation is of the order of 40 [CHI] 10-6 calorie per gm. per sec. This agrees with measurements made by others of the rate of O2 consumption during continual stimulation.