Abstract

Na+-K+-ATPase gene expression and activity were studied in aortas from adrenalectomized (ADX) rats and ADX rats with deoxycorticosterone supplement (ADX-DOCA). Northern analysis of RNA from ADX rats revealed a significant decrease in ?2-mRNA levels (38.5 ± 8.3% of control, P < 0.01) that was prevented by DOCA (P < 0.05). A decrease to 55.8 ± 7.7% in ?2-isoform protein was observed 8 days after adrenal removal (P < 0.05); DOCA reversed this effect (90.8 ± 10.5%). Adrenalectomy induced a decrease of 68.5 ± 4.5% in ?-mRNA (P < 0.01) and 52.7 ± 8.3% in ADX-DOCA rats (P < 0.01). Also, a reduction in ?1-isoform protein that was not prevented by DOCA was detected after adrenalectomy (47.1 ± 11%, P < 0.01). In contrast, no differences in ?1-mRNA or -protein levels were observed. Vascular sodium pump activity was reduced to 59.8 ± 4.6% of control values after adrenalectomy (P < 0.01); this reduction was reversed by DOCA. Our data indicate that corticosteroids regulate Na+-K+-ATPase isoform expression and activity in vascular tissue in vivo, suggesting a mineralocorticoid-dependent modulation of ?2-Na+- K+-ATPase gene expression in aorta, with ?1-isoform expression dependent on the presence of glucocorticoids.