Elemental concentrations in isolated rat thymocytes prepared for cryofixation in the presence of different media

Rat thymocytes were isolated in suspension and the effect of preparing the cells for cryofixation in the presence of different media on the elemental content was investigated using the technique of X-ray microanalysis. Cells prepared in the different media showed variation in the concentrations of Na, K and Cl. The isolated cells were incubated at 310 K for 1 h to allow recovery from isolation. There was a decrease in Na and Cl content after incubation. The thymocyte population was disturbed by suspension in medium containing dextran, and this resulted in a number of cells with high concentrations of Na and low concentrations of K. These cells did not take up vital dye. Thymocytes were also prepared for freezing by using high-speed centrifugation to concentrate the cells. Thymocytes prepared by this method showed values for concentrations of Na, K and Cl similar to published values for these cells using other methods of estimation. There were, however, consistent differences in Na content between the cells prepared in Hanks' balanced salt solution and those prepared in serum. Factors which affect the apparent concentration of Na and Cl in isolated cells are discussed.