Figure 4.Model of a putative amiloride-sensitive sodium channel (ENaC). The amiloride-sensitive sodium channel appears to consist of the α-, β- and γ- subunits and an amiloride-binding protein. This channel is located at the apical site of the renal epithelium and plays a role in passive sodium transport, which is mainly regulated by mineralocorticoids. (From Arai K, Shibasaki T, Chrousos GP. Pseudohypoaldosteronism: sporadic and familial mineralocorticoid resistance. In: Chrousos GP. Olefsky JM, Samols E, eds. Hormone Resistance and Hypersensitivity States. New York: Lippincott Williams & Wilkins; in press with permission)