The non-sugar reducing substances of human blood, with special reference to glutathione

Abstract

IN the preceding paper the behaviour of pure reduced glutathione in the various blood-sugar methods was described.In the present paper the effects produced by the non-sugar reducing substances of blood are determined, and are com- pared with those obtained with pure glutathione. EXPERIMENTAL.Freshly drawn, oxalated, venous blood of normal adults was used, and to each sample three methods of protein precipitation were applied.These were:(1) the Folin-Wu tungstic acid precipitation, which allows glutathione to pass into the filtrate, (2) the zinc hydroxide precipitation of Somogyi [1929, 1] in which the glutathione is removed, and (3) a new technique for preparing a glutathione-free filtrate with tungstic acid.Each of the three filtrates was analysed by the following methods: Hagedorn-Jensen [1923], Shaffer-Hartmann [Somogyi, 1926], Folin-Wu [1920] and Benedict [1928].In all precipi- tation methods the dilution of the blood was 1 in 10, so that for the Shaffer-Hartmann, Folin-Wu, and Benedict methods the volumes of filtrate described in the original methods were taken.In the ferricyanide method 1 cc.filtrate was used, and the volume was made up to about 12 cc.with distilled water before addition of the ferricyanide.This procedure is exactly comparable with the original Hagedorn-Jensen method, in which 01 cc. of blood is taken, and the volume of the filtrate from this, together with the washings, is about 12 cc.All filtrates were neutralised (to phenolphthalein) before use; the volume of alkali added was negligible in relation to the total volume.In the case of the zinc hydroxide filtrates the addition of the alkali caused a further precipitation of zinc hydroxide, which was removed by re-filtering.In the colorimetric methods readings were taken within 10 to 15 minutes after dilution of the coloured solution, and no fading of the colour took place