Interactions of erythrosin B (U.S. F, D & C Red 3) with rat cortical membranes

Erythrosin B inhibits Na,K-ATPase in rat brain tissue as demonstrated by studying glycoside binding, ATPase activity and ion fluxes. The potency of the noncompetitive inhibition of [3H]-ouabain binding by erythrosin B is influenced by glycoside concentration, monovalent cation concentration, and incubation time. [14C]-Erythrosin B binds to synaptic membranes prepared from rat cortex. Erythrosin B and some of its structural analogs inhibit both [3H]-ouabain and [14C]-erythrosin B binding, but ouabain and other glycosides do not inhibit the binding of [14C]-erythrosin B. Subcellular distributions of [3H]-ouabain and [14C]-erythrosin B binding in fractionated cortical tissue preparations are equivalent and parallel ATPase activity. The dissimilar response of [3H]-ouabain binding and [14C]-erythrosin B binding to changes in tissue preparation, incubation temperature, and partial solubilization of binding sites by deoxycholate (DOC) suggests two separate binding sites for erythrosin and ouabain to rat cortical membranes.