Effect of estradiol on the expression of renal sodium transporters in rats.

Background: Although estradiol has been thought to perform an important role in blood pressure regulation, the effects of estradiol on the expression of renal sodium transporters are not fully understood.

Methods: Female Sprague-Dawley rats were treated with 17β-estradiol or vehicle for 10 days after ovariectomy, and after both ovariectomy and adrenalectomy to eliminate the effect of aldosterone.

Results: In the ovariectomized (OVX) rats, estradiol decreased the abundance of the Na-K-2Cl cotransporter (NKCC2) (31.5% of control (OVX), p < 0.01), Na-Cl cotransporter (NCC) proteins (40.5% of control (OVX), p < 0.01) and α- and γ-subunits of the epithelial sodium channel (ENaC) (44.7% and 11.0% of control (OVX), p < 0.01). Estradiol also reduced plasma aldosterone levels (OVX + 17β-estradiol vs. OVX, 116.3 ± 44.4 vs. 184.2 ± 33.4 pmol/l, p < 0.05) and systolic blood pressure (OVX + 17β-estradiol vs. OVX, 115 ± 4 vs. 132 ± 2 mmHg, p < 0.05). In rats having undergone adrenalectomy and ovariectomy, estradiol did not reduce systolic blood pressure, or the expression of sodium transporters.

Conclusion: Estradiol decreased systolic blood pressure, plasma aldosterone levels, and the expression of renal sodium transporters. After aldosterone was eliminated, estradiol did not affect blood pressure or the expression of sodium transporters, which indicates that the effect of estradiol on the renal sodium transporters is at least partly influenced by aldosterone.