Proscillaridin A immunoreactivity: its purification, transport in blood by a specific binding protein and its correlation with blood pressure.

R Schneider, R Antolovic, H Kost, B Sich, U Kirch, M Tepel, W Zidek, W Schoner

Index: Clin. Exp. Hypertens. 20(5-6) , 593-9, (1998)

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Abstract

A material crossreacting with antibodies against the bufadienolide proscillaridin A and inhibiting the sodium pump was found in human blood plasma. The concentration of the material with a retention time similar to ouabain in a reversed phase HPLC correlated to systolic blood pressure and pulse pressure. Affinity purification of this compound from bovine adrenals resulted in the isolation of a compound with molecular mass of 600 Da that was not identical with ouabain. Consistent with the postulate that endogenous ouabain and proscillaridin A immunoreactivities may belong to a new class of cardiotonic steroid hormones, a protein of Mr = 60 kDa has been found in bovine serum by affinity-labeling with N-hydroxysuccimidyl digoxigenin-3-O-methylcarbonyl-epsilon-aminocaproate.