GLYCOGEN FORMATION IN THE LIVER FROM d- AND Z-LACTIC ACID

The question as to whether or not the liver is able to form glycogen from lactic acid is of importance for the relation between the carbohydrate metabolism of the muscles and that of the liver. It is known that the process glycogen * lactic acid occurs in the muscles, while the process glycogen e glucose occurs in the liver. Glucose derived from liver glycogen is convertible into muscle glycogen; it is, however, not definitely known whether lactic acid derived from muscle glycogen is convertible into liver glycogen. If this should prove to be the case, the glucose molecule would be capable of a complete cycle in the body; it could in turn be liver glycogen, blood sugar, muscle glycogen, blood lactic acid, and again liver glycogen. If, on the other hand, the liver is unable to form glycogen (or glucose) from lactic acid, this cycle would be interrupted as soon as the glucose molecule was deposited as muscle glycogen.