Effects of an intravenous saline load on erythrocyte sodium transport in normal human subjects.
The effects of a 2 litre intravenous infusion of saline (0.9% NaCl solution) over 3 h on erythrocyte transmembrane sodium transport were studied in 12 normal human subjects. After saline infusion a significant (P less than 0.01) reduction of both outward Na+,K+ pump- and Na+,K+ cotransport-mediated Na+ effluxes was observed. The Na+,Li+ countertransport rate and the passive Na+ permeability did not change. The incubation of the subjects' erythrocytes, obtained on a separate occasion, with their own plasma taken after the saline infusion, induced an inhibition of both Na+,K+ pump and Na+,K+ cotransport outward sodium fluxes. The percentage decrease after incubation was closely correlated with the percentage reduction induced by the saline infusion in vivo (r = 0.93 for the pump and r = 0.96 for cotransport; P less than 0.01). These data suggest that extracellular fluid volume expansion affects the release of circulating factors modulating sodium transport by the Na+,K+ pump and by Na+,K+ cotransport.
D000328:Adult; D001693:Biological Transport, Active / Q000187:drug effects; D004912:Erythrocytes / Q000378:metabolism*; D005110:Extracellular Space / Q000378:metabolism; D005260:Female; D006801:Humans; D008094:Lithium / Q000097:blood; D008297:Male; D011188:Potassium / Q000097:blood; D012964:Sodium / Q000097:blood*; D012965:Sodium Chloride / Q000494:pharmacology*; D014882:Water-Electrolyte Balance
D012965:Sodium Chloride; D008094:Lithium; D012964:Sodium; D011188:Potassium