Sodium reabsorption in the the nephron is an important mechanism to regulate total body sodium and fluid levels and control of blood pressure. The primary pathway for sodium reabsorption across tight epithelia in the tubules of the nephron is the amiloride-sensitive epithelial sodium channel (ENaC), composed of α, β, and γ subunits, each expressed by a different gene. Defects in these ENaCs in the kidney could affect the reabsorption of sodium and alter total body fluid balance leading to hypertension. Since glucocorticoids and mineralocorticoids alter renal sodium handling, we hypothesized that their primary effect is on ENaC gene expression. For this study we used the A6 toad (xenopus laevis) distal nephron cell line, which is a well established model to study transepithelial sodium transport in the kidney. The cells were treated with different hormones, antagonists and/or diluent for controls and harvested according to experimental protocols. Total RNA was isolated using the TRIzol method, and specific ENaC mRNA content was quantitated by a Ribonucleic Protection Assay(RPA) using custom designed cRNA probes. ENaCα gene expression was not induced by either mineralocorticoids (aldosterone) or glucocorticoids(cortisol). Aldosterone increased β and γ mRNA levels within 4 h with maximal effect by 8-12 h. Half maximal induction was seen at 30 to 100 nM concentrations. Cortisol increased β and γ mRNA levels only at higher concentrations (half maximal effect at 300 to 1000 nM). Using spironolactone and RU486 as specific mineralocorticoid and glucocorticoid receptor antagonists, we found that both cortisol and aldosterone altered ENaC gene expression by acting via the mineralocorticoid receptor. We conclude that both mineralocorticoids and glucocorticoids up-regulate ENaC β andγ genes in the kidney, but have no effect on the a subunit. We speculate that both mineralocorticoids and glucocorticoids affect total body sodium and fluid balance by a primary effect on ENaC β and γ gene expression.