Adrenal-dependent modulation of the catalytic subunit isoforms of the Na+-K+-ATPase in aorta

Na+-K+-ATPase gene expression and activity were studied in aortas from adre nalectomized (ADX) rats and ADX rats with deoxycorticosterone supplement (A DX-DOCA). Northern analysis of RNA from ADX rats revealed a significant dec rease in alpha(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 alpha(2)-isof orm protein was observed 8 days after adrenal removal (P < 0.05); DOCA reve rsed this effect (90.8 +/- 10.5%). Adrenalectomy induced a decrease of 68.5 +/- 4.5% in beta(1)-mRNA (P < 0.01) and 52.7 +/- 8.3% in ADX-DOCA rats (P < 0.01). Also, a reduction in pl-isoform protein that was not prevented by DOCA was detected after adrenalectomy (47.1 +/- 11%, P < 0.01). In contrast , no differences in alpha(1)-mRNA or -protein levels were observed. Vascula r 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 in dicate that corticosteroids regulate Na+-K+-ATPase isoform expression and a ctivity in vascular tissue in vivo, suggesting a mineralocorticoid-dependen t modulation of alpha(2)-Na+-K+-ATPase gene expression in aorta, with pl-is oform expression dependent on the presence of glucocorticoids.