The inhibition of lactic acid formation in cancer and muscle / by Sylvia Thurlow Harrison and Edward Mellanby.

  • Harrison, Sylvia Thurlow.
Date:
[1930?]
Catalogue details

Licence: In copyright

Credit: The inhibition of lactic acid formation in cancer and muscle / by Sylvia Thurlow Harrison and Edward Mellanby. Source: Wellcome Collection.

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    on the soluble muscle enzyme system of Meyerhof [1926], to which hexose- phosphate had already been added. The results are given in Table VII. For these experiments, the soluble muscle enzyme was prepared according to the directions of McCullagh. The quantities used in each flask were 8 cc. of muscle extract, 3 cc. phosphate buffer (made according to McCullagh), 4 cc. pan¬ creatic extract (Ronzoni, Glaser and Barr’s), 3 cc. 2-4 % substrate (starch, glucose, or hexosephosphate which was 2-4 % with respect to hexose), and 2 cc. water or yeast activator (made according to Meyerhof [1927]). 5 cc. of the contents of each flask were removed immediately into 1 cc. of 20 % trichloroacetic acid, these solutions serving as controls. The remainder was incubated for 4 hours at 37°, and then 3 cc. of 20 % trichloroacetic acid were added. After filtering off the proteins, the sugars, starch and hexosephosphate were precipitated in an aliquot neutralised portion by CuS04 and Ca(OH)2. This method precipitates not only glucose, but, as was shown by Embden and Zimmermann [1924], other carbohydrates including hexosephosphates. The lactic acid in an aliquot portion of the final filtrate was estimated by the method of Friedemann, Cotonio and Shaffer. Results are expressed in mg. of lactic acid produced by 10 cc. of soluble muscle enzyme. Controls were always done in which no substrate was added as there proved to be always a small formation of lactic acid with no added substrate. These control figures were subtracted from those obtained with solutions to which substrate was added. In Exp. 1, Table VII, barium hexosediphosphate was used. In the other experiments in this table, the calcium salt was used. P.E. designates pancreatic extract. For Exp. 12 in Table VII, the water extracts of pancreas, takadiastase and malt diastase were made by extracting 2 g. of dry preparation with 30 cc. water for 2 hours, filtering and neutralising. The saliva was diluted 1 : 5. In some of the experiments in which glucose was used as a substrate, an activator prepared from yeast by the method of Meyerhof was added. Meyerhof has shown that the soluble muscle enzyme system has in large part lost the power of changing glucose to lactic acid. This power he shows to be restored when yeast activator is added. The effect of pancreatic extract on glycolysis in the soluble muscle enzyme system is seen from the results in Table VII to be as follows. (1) When starch is the substrate, inhibition is brought about; (2) when hexosediphos¬ phate is the substrate, inhibition is again brought about; but (3) when hexosemonophosphate or (4) glucose plus yeast activator are the substrates, no appreciable inhibition occurs. The fact that pancreatic extract inhibits glycolysis in the soluble muscle enzyme system not only when starch is the substrate but also when hexose¬ diphosphate is used, shows that the inhibiting factor does not act by pre¬ venting the formation of hexosediphosphate, because when hexosediphosphate is added to the system, inhibition still occurs. The weight of evidence seems