Acid development as the result of injury in nervous tissue

Abstract

It was found possible to demonstrate the presence of acid in nervous tissue by the use of phenolsulphonephthalein as an indicator. The latter was employed in a 0.2 per cent. solution in Ringer's fluid, made slightly alkaline by the addition of one part of M/15 Na₂HPO₄ to four parts Ringer. Pieces of nervous tissue immersed in this solution take up sufficient dye in thirty minutes to show a striking reaction. In order to observe the reaction in brain substance, the brain of a frog was exposed by the removal of the roof of the skull, and the entire head immersed in the solution of phenolsulphonephthalein. When the preparation was examined thirty minutes later, the injured parts of the brain were bright yellow, indicating an acidity at least equivalent to PH = 6.5. The uninjured parts remained pink, but subsequent injury to them brought about the yellow coloration in a few seconds.

In similar fashion nerve trunks may be stained. The uninjured parts are pink, but crushed areas and the cut ends are yellow. Microscopic examination showed the yellow color to be located in the fibers near the point of injury. If a nerve be crushed at a point previously uninjured, the development of acidity is shown at once by the change in color from pink to yellow. Stimulation of the nerve for five minutes with induction shocks causes the acid reaction to develop between the electrodes. Previous treatment with chloroform does not interfere with the reaction, but heating to 50° C. in physiological salt solution inhibits it. Killing the nerve with chloroform or by high temperatures does not cause the development of acid.

Assuming that the acid in question is either lactic or carbonic, it is possible to show that it is the latter.