Studies on the Exchange of Potassium between Tumour Cell and Medium

Abstract

The present paper deals with the manner in which the exchange of potassium between tumour cell and medium is effected, and the means by which it may be controlled, a subject which appears to be of importance in view of the rOle of potassium in the life processes within the tumour cell. The investigation was suggested by the results of research on the influence of potassium and calcium upon the energy-metabolism, especially the fermentation capacity, of tumours (2)(3)(4)(5)(6)(7)(8). METHODSThe experiments were performed in vitro, and the general conditions were, as far as possible, the same as those employed in the metabolism experiments mentioned.Tumour Material: Jensen rat sarcoma was used, being particularly suitable as it contains little stroma. The tumours were produced in the usual way, by subcutaneous implantation of minced tumour tissue in adult rats.Treatment of the Tissue: In each experiment a tumour, removed immediately after the animal had been killed, was divided into several portions, the peripheral areas of which were cut, by means of a razor, into a fairly large number of thin slices. These were put, at room temperature, in groups, into Ringer's solution modified by varying the amounts of potassium and calcium. In the earlier experiments the portions of tumour were immersed in the solution and then sliced, the razor being moistened only with the particular solution concerned. In the later experiments the tumour, while being protected against drying, was cut into slices with a dry razor, and slices were put alternately into the various media. Both methods gave similar results. As far as possible the thickness of the slices was limited to that advocated by Warburg (1), but because of the necessity of employing all the available material the use of somewhat thicker slices could not be avoided. For our investigations, however, this should be of no consequence.After the removal of any necrotic tissue, the tumour slices were washed twice by agitating them carefully in 40 or 50 c.c. of the modified Ringer's solution for ten minutes. Then, after each slice had been rinsed rapidly in distilled water, they were transferred to weighing glasses. In the earlier experiments individual groups of slices were transferred to the weighing glasses one after the other, for the most part in the order in which they had been prepared; in the later experiments the slices belonging to the different groups were, as in their preparation, transferred alternately. In both instances it 513