Effect of Changes in Ion Concentration of Blood upon Reflex Time.

Abstract

Previous studies 1 , 2 on the effect of changes in acid-base equilibrium on the physiological action of strychnine and curare indicated that an increase in hydrogen or hydroxyl ions might affect neural or neuro-muscular factors and thus alter the rate of conduction of the nerve impulse.

Dogs were used as experimental animals. The patellar tendon reflex time of normal unanesthetized dogs varied from .00775 to .0094 seconds with an average of .0082 seconds. The pH of the blood of the normal dogs at the time the records were obtained was about 7.36 and the CO₂ capacity 45 volumes %. With a drop in pH and CO₂ capacity the reflex time was decreased to about .0043 seconds. An increase in pH and CO₂ capacity also brought about a decrease in reflex time. The average reflex time following alkali administration was .0057 seconds. One dog included here showed an insignificant increase of .0006 seconds in reflex conduction rate at pH 7.53 and CO₂ capacity 72.97 volumes %.

The records obtained show clearly that the reflex time of dogs is markedly reduced, following acid, and to a less degree, following alkali administration.

It is suggested that an increase in H ions probably blocks out the higher centers ordinarily involved in the arc. On the other hand OH ions probably aid in facilitating the conduction of the nerve impulse.