Na+,K+-activated adenosine triphosphatase of isolated Müller cells from the rabbit retina shows a K+ dependence similar to that of brain astrocytes.

Müller (glial) cells from the rabbit retina were isolated by means of papain and mechanical dissociation. Their Na+,K+-adenosine triphosphatase (ATPase) activity was measured using a radiochemical method, and its K+ dependence was determined. In contrast to that of photoreceptors (data from the literature), the Na+,K+-ATPase of Müller cells could be shown to increase its activity greatly when the [K+] was enhanced up to 10 mM. The functional implications of this behaviour for the K+ clearance in the retina are discussed.