Nerve heat production as a physiological response to excitation

Abstract
For many years attempts were made to record the energetic and metabolic changes in nerve associated with activity. Since 1926, when the heat production was first measured, a considerable amount of work has been published on the chemical and thermal changes and on the oxygen consumption and carbon dioxide production caused in nerve by stimulation. The regularity of the results obtained under all kinds of conditions (e. g., of frequency and duration of stimulus, of temperature, of the presence and absence of oxygen) and the general agreement between heat and oxygen measurements on the one hand and the electric response on the other, seemed to give assurance that a genuine physiological characteristic was being investigated. It has, however, been persistently objected by H. Winterstein that the increase observed, as the result of electric current passed through it and has nothing whatever to do with the normal process by which the impluse is propagated. This drastic view has been embodied in a text-book article (1932) in which "the regrettable conclusion" is reached that "the wonderful technique" developed for studying the heat production of the nervous system has led to no results of value as to the energetics of the physiological process of excitation. The experiments on which this opinion is based have been criticized in detail by Gerard (1932, where full reference will be found), by Meyerhof and Schulz (1930), by Schmitt (1933), by Hill, Fenn and Gerard (1934), by Harashima (1933), by Gerard and hartline (1934), and by Hill (1932, a, b). It can easily be calculated, moreover, that in the later experiments by Winterstein and his colleagues (e. g., Ledebur, 1933) on "reflex excitation" the method employed was so unreliable and the quantities to be observed so small that the negative results found were to be expected in any case. Since, however, the "regrettable conclusion" might, in spite of the evidence, confuse the issue the experiments to be described have been made in the hope of deciding the matter.

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