Determination of potassium flux activity of viable human erythrocytes by measuring the release-influx ratio

A simple and convenient method to determine the K+-flux activity of viable human erythrocytes was developed. Erythrocyte suspensions were incubated at 4 degrees C for 24 h to induce K+-release (Delta Kr) and then at 37 degrees C for 3 h to influx K+ into erythrocytes (Delta Ki). A straight-line relationship between K+ release-influx ratio and ouabain-induced K+-efflux from erythrocytes indicated that Delta Ki/Delta Kr ratio or the K+-flux activity was reflected predominantly by Na+/K+-exchanging ATPase activity. Using this method, K+-flux activity of erythrocytes in the young and the aged subjects was measured. The mean Delta Ki/Delta Kr ratio of the aged subjects was decreased significantly. This method of measuring Delta Ki/Delta Kr ratio is useful for the evaluation of K+-flux activity of viable erythrocytes. (C) 1999 Elsevier Science B.V. All rights reserved.