Angiotensin II stimulates elution of Na-K-ATPase from a digoxin-affinity column by increasing the kinetic response to ligands that trigger the decay of E2-P.

We earlier observed that treating rat proximal tubules with concentrations of angiotensin II (ANG II) that directly stimulate Na-K-ATPase activity changed how Na-K-ATPase subsequently eluted from an ouabain-affinity column. In this study we tested whether ANG II increases the rate of elution in response to ligands that trigger the decay of E(2)-P, which implies a change in functional properties of Na-K-ATPase, or by decreasing the amount subsequently eluted with SDS, which suggests a change in how Na-K-ATPase interacts with other proteins. We utilized a new digoxin-affinity column and novel lines of opossum kidney (OK) cells that coexpress the rat AT(1a) receptor and either the wild-type rat alpha(1)-isoform of Na-K-ATPase or a truncation mutant missing the first 32 amino acids of its NH(2) terminus.