The distribution of reducing substances between plasma and corpuscles; a comparison of various blood-sugar methods

Abstract

The ratio of "sugar" in plasma to that in corpuscles was determined in human venous blood collected in paraffin-coated tubes. The values of the ratio are: MacLean''s method, iron filtrates, 1.48; MacLean''s method, tungstic filtrates, 1.04; Hagedorn-Jensen, zinc fitrates, 1.34; Hagedorn-Jensen, tungstic fitrates, 0.85; Shaffer-Hartmann (Somogyi''s modification) 1.05; Folin-Wu 1.07; Benedict (1928) 1.34; the last 3 methods were applied only to tungstic filtrates. The average discrepancies between methods were not great for plasma, but were considerable for corpuscles. The ferricyanide method gave higher results on tungstic filtrates than on zinc filtrates (average discrepancy, plasma, 6, corpuscles, 56 mgm. per 100 cc). These effects are attributed to a non-glucose substance in corpuscles, of which a considerable amount passes into tungstic filtrates, but little or none into iron or zinc filtrates. The original methods of MacLean and Hagedorn-Jensen probably give true sugar figures because the filtrates used contain little non-sugar material. The Benedict method gives low figures because the non-sugar material has little effect on the copper reagent. All other methods give high corpuscle figures. Glutathione is suggested as the cause of these effects.