The histological distribution of glutathione reductase activity in solid mouse tumor transplants and a comparison with ascites tumors and normal tissues
The topographical distribution of GSSG reducÃ-aseactivity has been investigated at the histological level in solid unicentric transplants of three different types of auton omous mouse tumors. Assays have been performed on fresh frozen serial microtome sections, with an average protein content of about 20 ;ug.This technic permits sufficient separation in space for sampling of the peripheral tumor regions containing the young growing cells and the more central regions carrying older cell
... older cell generations. In continuous series of tumor sections there has been no proportionality between the observed activity and the pertinent tumor cell numbers per sample. The young and rapidly growing tumor cells have at least 4-6 times as much GSSG reducÃ-aseactivity per cell than the still vital nongrowing central tumor cell types. The distribution of GSSG reductase runs closely parallel to the catheptic activity of the same tumors. The GSSG reductase activity of solid tumors has been compared with that of ascites tumor cells and some normal mouse tissues. The calculated activity of the investigated growing tumor cell is about twice that of normal mouse liver cells. The average activity of two ascites tumor cell populations was found to be low, and that of cultured strain L cells was comparable with the activity of normal mouse fibroblasts. The marked biochemical differences between the two main classes of cells in solid tumor transplants have been emphasized. Attempts are being made to adapt quantitative (6). The method and its limitations have been deenzymic assay methods at the microscale for the scribed in detail (13). Unicentric tumor transstudy of the histological distribution of enzymes in plants present a certain advantage in the sense different regions of solid tumor transplants. It has that the distance in space is large enough between thus far been possible to investigate the distribu-the young growing cell generations at the periphtion of dipeptidases and cathepsins (13) and also ery and the more mature and older cell generations the arginase activity (7) at a scale of sampling cor-a few 100 /Â¿ nearer to the center. This allows separesponding to about 10 jug.of total protein content, rate sampling of the two main cell types A and B The sampling technic involves the use of fresh (3) and permits their biochemical characterizafrozen serial sections of punched-out cylinders tion, which is wanted in order to obtain more spetaken from unicentric tumor transplants; this is cific data than the ordinary macrochemical assay largely an adaptation of the original cryostat tech-methods are able to provide (cf. 7, 13). nie developed by LinderstrÃ ¶m-Lang and Holter As a consequence of previous studies on the dis-"¿ ",. .