Co-ordinated variations in chloride-dependent potassium transport and cell water in normal human erythrocytes.

1. The capacity of the loop-diuretic-sensitive Na+-K+-Cl- system in normal human erythrocytes shows tenfold interindividual variation between different donors, although the transport rate is constant from month to month for any one donor. 2. The present work shows that this variation in Na+-K+-Cl- transport is inversely correlated with a low-capacity loop-diuretic-insensitive K+ transport, which is chloride dependent and is stimulated by cell swelling in hypotonic media. 3. These variations in K+ transport from donor to donor are related to cell water. Those donors who show high loop-diuretic-sensitive Na+-K+-Cl- co-transport have lower cell water and vice versa.