Ouabain-Like and Non-Ouabain-Like Factors in Plasma of Patients with Essential Hypertension

Abstract

Circulating inhibitor of Na⁺, K⁺-ATPase and ouabain-like immuno-reactivity were studied in patients with essential hypertension. In the plasma of patients, two types of Na⁺, K⁺-ATPase inhibitors (ouabain-like and non-ouabain-like inhibitors) and ouabain-like immunoreactivity were detected. Ouabain-like inhibitor was clearly detected at a low KC1 concentration (0.1 mM) in the assay buffer, and non-ouabain-like inhibitor was detected at a high KC1 concentration (10 mM). The plasma level of ouabain-like inhibitor correlated significantly with that of ouabain-like immunoreactivity (p<0.001) and with a mean blood pressure (p<0.01). The plasma level of non-ouabain-like inhibitor was not correlated with the levels of either ouabain-like immunoreactivity or mean blood pressure. The level of plasma ouabain-like inhibitor did not correlate with that of plasma non-ouabain like inhibitor. Both ouabain-like inhibitor and ouabain-like immunoreactivity in the plasma of patients with essential hypertension were significantly higher than those in normotensive subjects, but the plasma level of non-ouabain-like inhibitor in patients with essential hypertension was not higher than that in normotensive subjects. These results suggest that the plasma from patients with essential hypertension contains ouabain-like factor(s) which is important to mantain the high blood pressure.

Key Words:

• ouabain-like Na⁺
• K⁺-ATPase inhibitor
• non-ouabain-like Na⁺
• K⁺-ATPase inhibitor
• essential hypertension