title: Sodium transport parameters in erythrocytes of patients with primary aldosteronism.
abstract: Primary aldosteronism is an uncommon cause of hypertension but one of particular interest because of its distinctive pathophysiological mechanism of blood pressure elevation. Aldosterone has been associated with increased Na+,K+-adenosine triphosphatase (ATPase) activity, but there is controversy over which sodium transport parameters are responsible for this increase. We measured intracellular sodium, ouabain-sensitive and ouabain-insensitive sodium efflux, and the number of Na+,K+-ATPase sites of washed erythrocytes, as well as Na+-Li+ countertransport and the Li+-K+ cotransport rate constant of lithium-loaded red blood cells (RBCs) in six patients with primary aldosteronism and in 50 normal subjects. Ouabain-sensitive sodium efflux was significantly (p less than 0.001) higher for the primary aldosteronism patients than for normal subjects (1.85 +/- 0.29 vs 1.51 +/- 0.21 mmol/L RBC/hr) even though the intracellular sodium concentration (7.2 +/- 1.5 vs 6.7 +/- 1.9 mM) and the number of the Na+,K+-ATPase sites per RBC (331 +/- 52 vs 385 +/- 97) were not increased. The elevated sodium efflux appeared to be due to a significant (p less than 0.001) increase in the rate constant (1.60 +/- 0.12 x 10(-15) vs 1.28 +/- 0.15 x 10(-15) mmol/site/hr) of the ouabain-sensitive sodium efflux. The rate constant decreased significantly (p less than 0.01) after treatment.
mesh_terms: D000328:Adult; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D006801:Humans; D006929:Hyperaldosteronism / Q000150:complications / Q000378:metabolism*; D006973:Hypertension / Q000209:etiology; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010042:Ouabain / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
chemical_list: D007473:Ion Channels; D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase