Plasma ouabain-like properties in hypertension and volume expansion

The presence in human plasma of compounds able to interact with the sodium pump has been investigated. The effects of whole and deproteinized plasma on the parameters of ouabain binding to the digitalis sites of the sodium pump were compared. Changes in the apparent affinity were potentialized by deproteinization. High levels of ouabain-like activity were observed to be present not only in some hypertensive patients but also in normotensive patients with chronic renal failure and active acromegaly, indicating a probable relationship with positive sodium balance and volemic expansion.