Intraerythrocytic sodium in dysmetabolic conditions
Testa, I.; Rabini, R.A.; Reginelli, R.; Recchioni, A.; Tocchini, M.; Testa, R.; Sprovieri, G.
Bollettino della Societa Italiana di Biologia Sperimentale 63(7): 621-628
1987
ISSN/ISBN: 0037-8771 PMID: 3311083 Document Number: 304412
In light of the observation that in vitro addition of insulin stimulates the Na,K ATPase activity in plasma membranes, the aim of the present study was to evaluate the effects of hyperinsulinemia on intraerythrocyte Na (Nai) in obese subjects. Plasma glucose, insulin, aldosterone, electrolytes, and Nai were measured during a 75-g oral glucose test in 16 healthy controls and 12 obese subjects. Nai was determined by ion-selective electrode analyzer in the hemolysates, after washing the erythrocytes in 110 mM MgCl2. Normal subjects showed a rise in Nai from a mean .+-. S.D. basal of 6.1 .+-. 0.9 mEq/1 to 9.6 .+-. 1.2 mEq/l at 60 min and to 10.3 .+-. 1 mEq/1 at 120 min (p < 0.01), while no change was observed in the obese group. There was a significantly higher insulin response in the obese subjects compared with controls. Aldosterone levels showed a fall in both groups. No correlation was found between insulin and Nai, while aldosterone showed a similar correlation with Nai in both groups (r = 0.66). The present study suggests that insulin levels may not play a major role in the control of Nai in vivo. Moreover, it indicates that obesity is accompanied by an abnormal response of intracellular electrolytes to dynamic stimuli, which remains to be further evaluated.