Kir subfamily in frog retina: specific spatial distribution of Kir 6.1 in glial (Muller) cells

We show by immunocytochemistry in frog retina that most members of the Kir subfamily are expressed in specific neuronal compartments. However, Kir 6.1 , the pore-forming subunit of K-ATP channels, is expressed exclusively in g lial Muller cells. Muller cell endfeet display strong Kir 6.1 immunolabel t hroughout the retina, whereas the somata are labeled only in the retinal pe riphery. This spatial pattern is similar to that of Kir 4.1, of the ratio o f inward to outward K+ currents, and of spermine/spermidine immunoreactivit y. We suggest that the co-expression of Kir 4.1 and Kir 6.1 subunits may en able the cells to maintain their high K+ conductance and hyperpolarized mem brane potentials both at high ATP levels (Kir 4.1) and during ATP deficienc y (Kir 6.1). NeuroReport 12:1437-1441 (C) 2001 Lippincott Williams & Wilkin s.