Effect of Neural Stimulation on Choline-Esterase Activity of the Blood

Abstract

Croxatto, Huidobro, Croxatto, and Salvestrini 1 published a paper showing an increase of almost 100% in the choline-esterase activity of the renal blood of the cat, during neural stimulation of the leg muscles. In an attempt to verify these findings, similar experiments were performed on the frog as well as on the cat with modified technics.

For the frog experiments, a perfusion technic was used. The cannulae were introduced into the dorsal aorta and the ventral abdominal vein as described by Fenn, et al. 2 The perfusion fluid was a mixture of gum acacia, Ringer's solution, and beef red blood cells. 3 Five experiments were done, analyzing only the supernatant fluid after the red cells had been removed by centrifugation, and one experiment in which the whole perfusion fluid was analyzed. In all cases, analyses were made of arterial samples and of venous samples taken, (a) in the resting state, (b) during about 10 minutes of electrical stimulation of the leg muscles through the sciatic nerve, and, (c) after stimulation had ceased. The stimulation was accomplished by means of a condenser discharge type stimulator. The frequency and intensity of the shocks were adjusted to produce maximal contraction and were not constant. The samples were analyzed for choline-esterase with the differential volumeter apparatus of Fenn 4 according to the principle used by Stedman and Stedman. 5 One cc of bicarbonate buffer (.65% NaCl and .4% NaHCO₃), and one-half cc of 1% acetylcholine solution in saline were placed in the bottom of the flask, and 1/32 to 1/4 cc of the test solution, depending on the activity, was placed in the side arm. In cases where there was appreciable hemolysis of the red blood cells, the degree of hemolysis was determined by measuring the hemoglobin content of the supernatant fluid by dilution and color comparison.