The effect of bumetanide on cation transport in human red blood cells

Bumetanide, a sulfamyl-aminobenzoic acid derivative, is a new and highly effective diuretic agent. The present studies were designed to examine its effects on cation transport in human red cells. At a concentration of 10(-3) M, the drug inhibited both active and passive unidirectional sodium fluxes, as well as active potassium influx. It also caused a significant inhibition of glycolysis. The inhibition caused by bumetanide was less than that seen with ouabain alone, but a bumetanide effect was also present in ouabain-treated cells. Bumetanide had no effect on red cell Na-K adenosine triphosphatase activity and did not affect net transport of sodium in sodium-loaded cells. The data are consistent with a model in which the inhibition of monovalent cation movement in red cells by bumetanide is related to an effect of this compound in decreasing the permeability of the red cell membrane to sodium.