Heterogeneity of NH4(super +) transport in mouse inner medullary collecting duct cells

Na+ -K+ -2Cl cotransporter regulates proportional transport of K+ and NH4+, which are potent inhibitors of the extracellular K+ binding site. The cotransporter is present on basolateral membrane of the inner medullary collecting duct (IMCD) and the rate of NH4+ transport depends upon the interstitial levels of K+ and NH4+. In analyzing NH4+ transport, Rb+ is used as K+ congener. Infusion of K+ and NH4+ decreases bumetanide- and ouabain-susceptible Rb+ uptake.