Species differences between rat and rabbit renal Na+/H+ exchangers.

Amiloride, 5-ethylisopropylamiloride (EIPA), and 5-ethylisopropyl-6-bromo-amiloride (Br-EIPA) inhibit rabbit and rat renal Na+/H+ exchangers with comparable potency. Irreversible inhibitions by Br-EIPA after irradiation of rat and rabbit renal brush-border vesicles are also similar. In contrast, irreversible inhibition by N,N'-dicyclohexylcarbodiimide (DCCD) of the rabbit renal antiporter requires higher DCCD concentrations as compared to the rat. Rabbit renal brush-border membranes show highest [14C]DCCD incorporation at MW 80,000, 51,000 and 36,000 and lack the amiloride-protectable MW 65,000 protein previously identified as Na+/H+ exchanger in rat kidney cortex. The data indicate species differences with respect to renal Na+/H+ exchangers.