Measurement of ion flux and concentration in fibroblastic cells

Techniques for the measurement of cell volume, intracellular Na and K concentrations, Na-K pump activity, 86Rb efflux, 22Na uptake, intracellular pH, 45Ca uptake and efflux, and intracellular Ca concentration have been described. The technique for washing and solubilizing the cells is similar in many of these methods. This allows several measurements to be made on the same culture. Measurement of 86Rb uptake and intracellular Na and K in the same sample has been discussed above. It is also possible to measure 86Rb uptake and [14C]DMO distribution in a single dish. There are other possible combinations of these methods. In addition, aspects of ion transport can be measured along with the assessment of macromolecular synthesis by measuring the incorporation of labeled amino acids or thymidine into TCA-insoluble material. We have used these techniques to study the effect of such mitogens as serum, platelet-derived growth factor, vasopressin, tumor promoters, fibroblast-derived growth factor, and others on Na-K pump activity, Na uptake, intracellular pH, Ca efflux, and [Ca]i.