Preliminary characterization of an Na+,K+,Cl- co-transport activity in cultured human astrocytes

We have studied the potassium uptake using 86Rb+ into monolayers of secondary cultures of human astrocytes prepared from cerebral hemispheres of a 4-month-old fetus. With the use of inhibitors we could attribute 30-40% of the 86Rb+ uptake to an Na+,K+-ATPase, 50-60% to an anion-cation co-transporter and 10% to potassium leak channels. The anion-cation co-transporter was dependent on the simultaneous presence of both sodium and chloride in the incubation medium and is therefore most likely an Na+,K+,Cl- co-transporter. This is the first evidence of such an Na+,K+,Cl- co-transport in human astrocytes.