Chemical Studies on Tumor Tissue: VI. Comparative Effects of Serum Colloids and of Salts on the Swelling of Mouse Tumor Cells in vitro

Introduction The swelling of mouse tumor cells in salt solutions has been described in previous communications (Shear and Fogg, 1934; Shear, 1935). The swollen cells usually exhibit blisters, or bulges, of clear fluid underneath the cell membrane. These accumulations of fluid form within a few minutes and frequently attain a volume equal to that of the cell initially (for photographs, see Shear, 1935). As previously stated, ”This swelling was independent of the salt concentration and occurred in salt solutions which were hypertonic, as well as isotonic and hypotonic, to salt solutions having the same inorganic composition as blood plasma.“ The only factor which was found to control the swelling was the presence of colloids, such as proteins. The numerous data obtained by various investigators on osmotic properties of free cells such as marine ova, erythrocytes, and plant cells have usually been considered as showing that for such cells the salt content of the environment is, in general, the determining factor in osmosis; i.e. , in certain salt concentrations (isotonic) the cell volume remains unchanged, whereas in more concentrated salt solutions (hypertonic) the cells shrink, and in more dilute salt solutions (hypotonic) the cells swell. In the case of cells of normal and malignant solid tissues of mice in our experiments, however, the oncotic (colloid osmotic) pressure, rather than the osmotic pressure of the salts, seems to play the predominant role. The present paper reports experiments designed to evaluate the relative importance of salt concentration and of colloid concentration on the bulging phenomenon in mouse tumor cells. The comparative significance of these two factors was ascertained by observations upon cell swelling in solutions of varying salt and protein concentration.