The Effects of Roentgen Rays and Radioactive Substances on Living Cells and Tissues

Abstract

1. SOURCES OF RADIANT ENERGY WITHIN THE BODY In estimating the effects of radiant energy in our cells and tissues, we usually leave out of consideration the presence of a considerable source of it within our body. Zwaardemaker, as did others before him, called attention to the fact that potassium, which is an important constituent of certain parts of our tissues, is radioactive; it gives off very penetrating beta rays as well as gamma rays. He believes that potassium, which is required for the equilibrization of body fluids acts, not through its chemical properties, but as a radioactive substance; it can be substituted for by various other radioactive substances, by alpha as well as beta rays. Radioactivity is thus of importance in maintaining the automaticity of the heart action, of the movements of the intestines; it helps to regulate the permeability of the capillary endothelium and thus prevents edema, if acting in the right proportions; it determines also the permeability of the glomerulus for sugar. This view as to the mode of function of potassium has not been generally accepted. One of the principal objections against it rests on the fact that the functions of potassium may be taken over not only by rubidium, which likewise shows some, although a weak, radioactivity, but, in certain cases, even by caesium, which is not known to give off either beta or gamma rays. Yet, as R. F. Loeb has shown, caesium can take the place of potassium in a balanced solution which permits echinoderm eggs to develop. Furthermore studies by Hamburger have shown that these functions of radioactive substances are not indispensible, but that a combination of salts, in which a somewhat larger amount of calcium is used than in Ringer's solution, acts equally well, even if radioactive substances are entirely lacking. It is therefore at present still doubtful whether radioactive substances exert a physiological function in the organism.