Effects of pyridoxal and indoleacetate on cell uptake of amino acids and potassium
Journal of Biological Chemistry
Pyridoxal was recently found in this laboratory to increase the extent to which amino acids can be concentrated from a suspending fluid by the Ehrlich mouse ascites carcinoma cell (2). In the present study of this activity, we have encountered a second group of stimulating substances, including indoleacetic acid and other auxin-like structures. The action of these two dissimilar classes, pyridoxal on one hand and the aromatic acids on the other, has been found to have in common effects upon the
... distribution of potassium which are closely related to their effects upon amino acid distribution. EXPERIMENTa The general methods of studying the concentration of amino acids in vitro by the carcinoma cells and the shifts of electrolytes and water of erythrocytes and carcinoma cells have been described previously (3-5). Erythrocytes were incubated in the medium of Raker et al. (6) . The electrolyte losses were corrected for small shifts in control cells incubated in parallel experiments. The distribution of pyridoxal was examined by the absorption in the ultraviolet region of aqueous extracts, deproteinized by heat at pH 5.0. Indoleacetate was measured by the method of Bat.es for tryptophan (7) applied to similar extracts. The several agents studied replaced isosmotically part of the sodium chloride of the Krebs' Ringer-bicarbonate medium. Samples of pyridoxal and indoleacetic acid, each from two different sources, were taken without difference in effect. Pyridoxine Deficiency in Tumor-Bearing Mice-The mice were fed a pyridoxine-free diet modified from that of Miller and Baumann (8) , containing 30 per cent casein. The tumor cells were introduced 1 to 3 weeks later. More severe deficiencies greatly slowed or prevented the multiplication of the neoplastic cells. Xanthurenic acid excretion confirmed the deficiency.