OTHER REDUCING SYSTEMS IN THE ERYTHROCYTE 517 



Reduced glutathione may be necessary for the stahihty of the erythrocyte. 

 Keihn and Hartree (l^OS) found that cells in which hem/glohin had been 

 formed by nitrite commenced to hemolyze in 11 hours. They found all the 

 glutathione in such nitrite cells in the oxidized state. Glutatliione reduces 

 hemoglobin {1991). as does cysteine {f>Jtl,l-'j26,2ST)Jf.). 



Reduced glutathione has been shown by a number of workers {1710), 

 {cf. also Section 3. 3. '•2.) to reduce dehydroascorbic acid. In ascorbic acid 

 saturation tests, Prunty {2191) found a significant negative correlation 

 between the ascorbic acid content of the blood and the reduced glutathione 

 in the corpuscles, with indications of an increase of oxidized glutathione 

 accompanying the decrease of reduced glutathione. If the factors (Chapter 

 X, 4.4.'2.), which normally prevent hemoglobin from undergoing oxidative 

 destruction by coupled oxidation with ascorbic acid, became inactive, even 

 the traces of ascorbic acid which are probably present in the erythrocyte 

 would be able to function together with the glutathione - hexose monophos- 

 phate mechanism as the coenzyme for hemoglobin destruction. Under 

 certain conditions glutathione is also able to assist in the destruction of 

 catalase {cf. Chapter IX, Section "2.4. and 2398). No evidence is available 

 on the question of whether this reaction takes place in the erythrocyte or 

 whether philocatalases are present in the erythrocyte. Jowett and Quastel 

 {IJtSG) could find no evidence that the erythrocyte was permeable to reduced 

 glutathione. Since it is unlikely that the mature cell is able to synthesize 

 this compound, the quantity present must be regarded as having originated 

 at some stage in the cell synthesis. During the increased blood destruction 

 after birth, the total blood glutathione falls, while its concentration in the 

 remaining erythrocytes is increased {IS^l). 



3.3.2. Ascorbic Acid. Unless special precautions are taken {1702), the 

 determination of reduced ascorbic acid in hemolyzed blood and perhaps also 

 in total blood is likely to give erroneous values owing to the peroxidative 

 action of acidified o.xyhemoglobin, although Kassan and Roe {H71) and 

 Heinemann {1227) claim that if the protein precipitant is added to the intact 

 erythrocyte the destruction of ascorbic acid does not take place (cf., however, 

 Borsook et al., 320). Van Eekelen {GJ^8) found 0.34 mg. ascorbic acid per 

 100 ml. present in erythrocytes (using reduction of the protein-free filtrate 

 with hydrogen sulfide), while Stevens and Hawley {2G24-), who apparently 

 added trichloracetic acid to intact erythrocytes, found the normal range to 

 lie between 0.7 and 1.0 mg. per 100 ml. Borsook and co-workers {320) added 

 ascorbic acid to the defibrinated or oxalated bloods of seven species, and con- 

 cluded from their recoveries in plasma that, with the exception of pig and 

 sheep, the erythrocytes of the other species, including man. were almost 

 impermeable to ascorbic acid. If proper precautions are taken, however, the 

 direct analysis would be expected to give rather more reliable results; Heine- 

 mann and Hald {1228) have observed a slow uptake of ascorbic acid by the 

 erythrocytes. In agreement with the finding of van Eekelen and of Stevens 

 and Hawley, Lemberg and co-workers {1710) found 0.35 mg. per 100 ml. 

 in rabbit erythrocytes, while Heinemann {1227) also confirms the presence 

 of small amounts of ascorbic acid in human ervthrocvtes. 



