The Oxidation of Glutathione in Human Erythrocytes—A Reversible Reaction.

Abstract

The observations here reported have been made while working on an adaptation for human blood of Tunnicliffe's 1 method for the determination of a reduced glutathione. A complete report of these studies will appear later.

The general plan of the experiments was as follows: a given specimen of human blood was saturated with CO₂, a sample or samples removed for estimation of reduced glutathione; the remaining blood was saturated with air, again sampled and the remainder saturated a second time with CO₂ and a portion taken for determination of reduced glutathione. Saturation with CO₂ or with air was accomplished by shaking the blood gently in a 250 cc. Erlenmeyer flask in a specially designed motor-driven apparatus as a stream of moist CO₂ or air was passed through the flask. Samples were removed with a 10 cc. Oswald-Folin pipette and allowed to run into 10% trichloracetic acid. The samples which were saturated with CO₂ were run into the acid contained in flasks in which the air had been replaced by CO₂. The trichloracetic acid filtrates were titrated with 0.001 N iodine solution to the starch end point and with 0.001 N thiosulphate to the disappearance of color, as suggested by Perlzweig and Delrue. 2 The excess of potassium iodide they suggest was omitted. The nitroprusside reaction as an outside indicator has been used as a check on the starch indicator in a large number of determinations on human blood. When the nitroprusside end point is used the figures obtained are from 85% to 95% of those obtained with filtrates containing a higher concentration of reduced glutathione and poorer agreement when the concentration is less. It appears that the same substance is being measured by either of the indicators and starch is much more accurate in my hands.