STUDIES ON NERVE METABOLISM

IN previous papers (1, 2,3) it has been shown that activity of nerve is associated with a definite heat production, and the absolute value for a single impulse obtained. This heat appears in two phases, an initial very short and intense one associated with the actual conduction and immediate restitutive processes, and a delayed feeble but very prolonged one associated with "recovery" processes. In the case of muscle, which shows two similar phases, the delayed heat is almost all oxidative, since it disappears in oxygen lack, whereas the initial heat is non-oxidative, being independent of oxygen supply. It was expected that a similar mechanism would be found in nerve, possibly based, as in muscle, on a glycogen-lactic acid system. The present research represents an attempt to expose the nerve mechanism; and the results obtained do not support this hypothesis, but do not positively eliminate it. The problem is being followed further by chemical methods. Especially interesting is the evidence that for minutes after activity a nerve has not returned to rest-not only does extra heat production last long after conduction is over, but potential or permeability changes may also considerably outlast the transmitted impulse (see Levin(4) and Verzar(5)). The dependence of these electrical changes on the presence of oxygen has been much studied but the results can hardly yet be given a sound interpretation.