Inhibition of Lactic Acid Formation in Muscle by Extract of Desiccated Pancreas.

Abstract

Hopkins and Winfield 1 showed that extracts of pancreas could inhibit the formation of lactic acid in chopped muscle. This work did not exclude the possibility that the inhibitory factor was trypsin. Foster and Woodrow 2 working in Hopkins' laboratory made further investigation of this substance. They found that it was neither trypsin, insulin nor anti-gloxylase, and that heating it for 10 minutes at 85° C. greatly reduced its activity but did not completely destroy it. They reported an inhibition between 40 and 60% of the total lactic acid which was formed in control samples of muscles, a fact which they interpreted as evidence of two mechanisms for lactic acid production in muscle, one of which was inhibited by the pancreatic factor.

In an attempt to determine the mechanism of the action of this substance, we confirm the observations of Foster and Woodrow, 2 obtaining an inhibition of between 40 and 60% of the total lactic acid production in muscle hash in concentrations similar to theirs (extract of 5 mg. of desiccated pancreas acting on between 3 and 4 gm. of muscle in 10 cc. of phosphate buffer). Increasing the concentration produces no greater inhibition. This action is not due to trypsin as Foster has demonstrated. That the inhibiting factor, as prepared, usually contains no trypsin is shown by the fact that filtrates after HgC12 precipitation of the proteins give no Biuret test. The non-protein nitrogen content of muscle extracts treated for 3 hours with the inhibiting factor usually shows no increase. In a few cases, there occurs a rise from 1 to 2 mg. percent, an increase which does not affect the inhibitory action of the extract upon lactic acid formation.