Increased Activity of Digoxin-Like Substance in Low-Renin Hypertension in Acromegaly

Abstract

Arterial hypertension is common in acromegaly, but the pathogenesis of this complication remains unknown. To determine the role of an endogenous Na, K pump inhibitor/digoxin-like substance (DLS) in the pathogensis of hypertension in acromegaly 76 subjects: 28 with acromegaly, 20 with essential hypertension and 28 healthy controls were studied. Serum DLS was measured with the use of radioimmunoassay and bioassay by the inhibition of digoxin-sensitive erythrocyte 86-Rb uptake.

In acromegaly, the activity of DLS was significantly increased and plasma renin activity decreased in the hypertensive group, as compared with that of the normotensive group and controls. Moreover, DLS was elevated in the low-renin group of essential hypertension, as compared with that of the normal-high-renin group or controls. The activity of DLS correlated positively with mean arterial pressure and negatively with plasma renin activity, but not with growth hormone levels.

In conclusion: an endogenous sodium pump inhibitor/digoxin-like substance may play a role in the pathogensis of low-renin hypertension in acromegaly.

Key Words:

• Na,K pump inhibitor
• Digoxin-like substance
• ⁸⁶Rb uptake
• acromegaly
• essential hypertension
• plasma renin activity