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

Muller (glial) cells from the rabbit retina were isolated by means of papaine 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 Muller 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.