Sulfation of 1-Naphthol in Isolated Rat Hepatocytes. Dependence on Inorganic Sulfate

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Abstract
The dependence of 1-naphthol sulfation on inorganic sulfate levels was studied in isolated hepatocytes. Rates of sulfation of 1-naphthol (190 .mu.M) depended on extracellular sulfate in a nonlinear relationship, i.e., the dependence was more expressed at sulfate levels of the medium < 200 .mu.M than at higher concentrations of the inorganic anion. The intracellular steady state concentrations of 35SO42- were a nonlinear function of the extracellular sulfate levels, i.e., at low concentrations of extracellular sulfate the intracellular levels exceeded those of the medium, while at > 500 .mu.M the ratio of the intracellular vs. extracellular concentrations was < 1. The apparent Km value for intracellular sulfate in the overall sulfation of 1-napthol was .apprx. 500 .mu.M. 4-Nitrophenyl sulfate markedly stimulated the formation of 1-naphthyl sulfate in intact cells and in cells permeabilized by freezing/thawing.