Two bumetanide-sensitive ion cotransporters that carry Na+, K+, and Cl-in a coupled fashion
have been identified. One type, the" absorptive" isoform, carries these ions across the apical
plasma membrane of the thick ascending limb of Henle's loop. Another isoform, the"
secretory" cotransporter, has been identified in a number of epithelial tissues by
physiological means, but its sites of expression in the kidney have not been fully
characterized. Complementary DNA believed to code for the secretory isoform (called" …