Antibody against Na/K-ATPase inhibitor lowers blood pressure and increases vascular Fli1 in experimental preeclampsia.

BACKGROUND Previous studies implicated cardiotonic steroids, including Na/K-ATPase inhibitor marinobufagenin (MBG), in the pathogenesis of preeclampsia (PE). We demonstrated that MBG induces fibrosis via mechanism involving inhibition of Fli1, a nuclear transcription factor and a negative regulator of collagen-1 synthesis. We hypothesized that PE blockade of increased MBG with antibody would lessen the fibrosis of umbilical arteries and lower the blood pressure in rats with PE. METHODS We tested 36 pregnant Sprague-Dawley rats in which 12 were made hypertensive by 1.8% Na supplementation (days 6-19 of gestation), 12 pregnant rats served controls. At day 19, PE rats received one intraperitoneal injection of polyclonal anti-MBG-4 antibody (0.5 ug/ml) for 4 hours. RESULTS PE was associated with higher blood pressure (117 2 vs. 107 +/- 2 mm Hg; P < 0.01), plasma MBG levels (1.54 +/- 0.34 vs. 0.49 +/- 0.11 nmol/L; P < 0.01), protein excretion (26 vs. 12 mg/24 hours), sFlt-1 (3-fold), decrease in Fli1 (7-fold) and increase in collagen-1 in aorta (4-fold) vs. control rats (all P < 0.01). In 12 rats treated with polyclonal anti-MBG-4 antibody blood pressure dropped (93 +/- 3 mm Hg) and Fli1 was decreased much less (2-fold; P < 0.01 vs. nontreated rats). CONCLUSIONS These results demonstrate that in experimental PE elevated MBG level is implicated in umbilical fibrosis via suppression of Fli1.