THE OXYGEN CONSUMPTION OF STIMULATED NERVE

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Abstract
A sensitive method is described for the simultaneous measurement of the O2 consumption, electric response (spike and after-potential), strength, and frequency of stimulation. The respirometer is a volumeter sensitive to change in vol. of the order of 5 X 10-7 cc. In av. good exps. it has been possible to measure the respiration of a 10 mgm. nerve (wet wt.) with variations of less than 2-3% for 2 min. readings. This accuracy has been made possible by the use of a thermostat specially designed to eliminate temp. pockets and to maintain the av. temp. constant within 0.001[degree] C. The electric response is measured oscillographically, the amplifier being capable of a voltage amplification of the order of 106. The amplifier is a thyratron device designed to give quantitatively controllable shocks at any frequency up to 500 per sec. A contribution is made to the controversy regarding the artificiality of the excess O2 consumption which results from direct electrical stimulation of nerve. It can be shown by 3 distinct methods that the small increase (15%) in respiration of American green frog sciatics and bull frog motor roots resulting from stimulation depends upon the production of action potentials and is independent of the electrical energy of the stimuli. The absolute increase of respiration resulting from stimulation varies only qualitatively with spike height. The suggestion of Winterstein that the physiological propagation of the impulse is not associated with increased O2 consumption is discussed.

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