Journal of hypertension
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Journal of hypertension · May 1991
Does a digoxin-like substance participate in vascular and pressure control during dietary sodium changes in patients with primary aldosteronism?
To evaluate the importance of an endogenous sodium pump inhibitor in the pathogenesis of low renin human hypertension, the urinary excretion of a digoxin-like immunoreactive substance (DLIS) was measured in eight patients with primary aldosteronism (n = 5, with adenomas) during two sequential 1-week periods of low- (20 mmol/l NaCl) and high- (200 mmol/l NaCl) sodium intake. DLIS excretion increased consistently during high-sodium intake while urinary aldosterone, plasma renin activity, cortisol and adrenocorticotropic hormone did not change. Although blood pressure showed a time-course parallel to that of the urinary DLIS, the blood pressure increments were not accompanied by evidence of vasoconstriction since forearm blood flow (plethysmographic technique) increased and forearm vascular resistances were reduced. ⋯ These results provide unequivocal evidence for a modulation by salt intake of the urinary excretion of a DLIS in patients with primary aldosteronism. This substance might participate in the regulation of body fluid volume in this syndrome and possibly in other physiological conditions. However, no evidence could be found for a cause--effect relationship between blood pressure and DLIS increments during high-salt intake, at least during the short-term course of the study.