The relation between initial and recovery heat production in frog's nerve

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Abstract
After a short stimulus (e.g., 16 to 32 sec.) to a completely resting frog''s nerve at 20[degree] C. the recovery process is complete only in 30 to 35 min. The ratio of total heat to initial heat is about 30. When a nerve is stimulated continually at not too high a frequency a steady state is reached in about 30 min. in which the rate of heat production (above "basal") is constant. If the stimulus be omitted for a short time (e.g., 16 sec.) a "gap" in the heat production occurs which can be analyzed in the usual way. This provides a rather accurate estimate of the initial heat during the steady state. The ratio of the total heat to the initial heat so measured is about 9. A nerve in a steady state of activity can be stimulated to a higher degree of activity by increasing the frequency of stimulation for a short time (e.g., 32 sec.). The heat so produced can be analyzed in the usual way, treating the level of steady activity as a base line. The ratio of total to initial heat, for the superimposed stimulus, may vary from 30 to 7, depending on the level of the basal activity, being less the greater that activity. The nearer the basal steady condition of a nerve is to one of complete rest the higher is the "potential" to which it is restored during recovery, and the greater is the amount of energy used in its restoration. Hypertonic and hypotonic solutions affect the ratio of total to initial heat in a characteristic way. The wide variation, in nerve under different conditions, of the ratio of total to initial heat suggests that the initial and the recovery processes are not directly coupled (e.g., chemically) ; the former is doubtless the consequence of the latter, but the efficiency, or degree, of recovery varies with the circumstances.

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