Changes in Lactic Acid and Glucose in the Blood on Passage Through Organs.

Abstract

The following research was undertaken to determine the factors regulating the concentration of lactic acid in the blood of mammals. Observations were made on 32 dogs most of which were decerebrate. The amount of lactic acid in the arterial blood was compared with that of the blood draining the liver, spleen, portal system, kidney, testicle, lower extremities, brain, thyroid, lungs and heart. Lactic acid was estimated by the method of Shaffer, Cotonio and Friedemann. Sugar was determined by the Shaffer-Hartmann method. A difference of 5 mg. % or more between the lactic acid content in the arterial and venous samples was considered significant. Typical results are found in Table I, where the muscle poured lactic acid in the blood stream and the liver removed it. Thus, in 27 of 51 observations the muscles added to the lactic acid content of the blood passing through them. In 19 cases the difference between arterial and venous blood was not considered significant, and in 5 instances only did the muscles remove lactic acid. On the other hand, in 21 of 34 observations the liver removed lactic acid. However, in 6 instances the liver was adding lactic acid to the blood and therefore could not explain the lower arterial level. It is clear that some organ other than the liver was removing lactic acid. Results from many of the organs were not constant. Sometimes they would remove lactic acid from the blood though in decerebrate animals they usually added lactic acid. We next studied the heart. As seen in Table I1 the heart, in 6 observations, was removing lactic acid from the blood passing through it. Even small differences are significant in the heart because of its relatively large vascular supply.