Divalent cation transport in kidney slices II. Magnesium transport in kidney cortex slices and effects of diuretics.

We examined the properties of Mg2+ transport in rat kidney cortex slices and the effects of diuretics were also studied. Incubation with 1 mM 2,4-dinitrophenol, or under anaerobic conditions, sharply inhibited Mg2+ influx, while markedly stimulating Mg2+ efflux. Under conditions of hypothermia, partial inhibition of Mg2+ influx and significant enhancement of Mg2+ efflux were observed. Mg2+ influx was not affected by ouabain, by altering CaCl2 concentration in the medium, or by a change of Ca2+ content in the slices. Incubation with 1 mM ethacrynic acid or mersalyl depressed Mg2+ influx and stimulated Mg2+ efflux, p-chloromercuribenzoic acid (5 X 10(-4) M) had a similar effect and furosemide had no effect on Mg2+ transport. These results suggest that Mg2+ influx is mediated by an energy-dependent process which is dissociated from ouabain-sensitive Na+ transport and Ca2+ flux. Sulfhydryl groups may be involved in the process of Mg2+ influx.