ABSTRACT
Furosemide blocks the action of the Na+ /K+ /2Cl - cotransporters on the cells of the thick ascending limb of the loop of Henle that are so important in concentration of the urine, leading to increased fluid loss in the urine. Bendroflumethiazide blocks the Na+ /Cl - cotransporter on the epithelial cells of the DCT, and hence is a less potent diuretic than furosemide, since only a small amount of filtered fluid is reabsorbed in the DCT. One potential adverse effect of these diuretics is that they promote K+ loss in the urine, which can lead to hypokalemia in some cases. This effect is due to increased presentation of Na+
to the aldosterone-sensitive site at which exchange for K+ occurs, and also to the increased tubular flow rate causing K+ washout.
