THE RELATION OF THRESHOLD OF EXCITABILITY OF NERVE TO CARBON DIOXIDE TENSION

Abstract

The action potential threshold of green frog sciatic nerve was systematically and graphically examined at CO2 tensions from 1.5 to 180 mm. Hg. Minimal and maximal thresholds were invariably raised by any increase of CO2 above that which exists in the tissue due to its own production. Maximum threshold level reached was dependent on the tension. Time required for maximum depressant effect was that required for gas diffusion into the tissue. Removal of CO2 gave complete recovery of threshold for tensions below 35 mm. Hg. Above that tension recovery was incomplete and deterioration of the nerve seemed to be accelerated.