NARCOSIS AND THE CHRONAXIE

¹ From the Department of Pharmacology of the Vanderbilt University School o Medicine, Nashville, Tennessee

The agents cocaine hydrochloride, chloral hydrate, and urethane produce in frog nerve a reversible reduction in excitability, indicated by a shift in the intensity-duration curve of threshold electrical stimuli. The change is in excitability rather than conductivity, as there occurs a rise in threshold short of complete block. The chronaxie, which shows a fall often preceded by a rise, bears a false relationship to the true excitability as judged by the intensity-duration curves and is not an index of the excitability of nerve during narcosis. This circumstance is independent of the nature of the stimulating electrodes, and is not due to the possible interference of an "alpha" effect, or the determination of pseudochronaxies. Although no other time value of the stimulus, such as that for minimal energy, appears to be directly related to excitability in narcosis, this may be expressed by the value for minimal energy itself.