Effects of membrane incorporation of short-chain phospholipids on sodium pump function in human erthrocytes.
Erythrocyte membrane incorporation of exogenous short-chain diacyl phosphatidylcholines (PC) has been quantified by gas chromatography of fatty acid methyl esters of extracted membrane lipids after incubation of cells with sonicated aqueous suspensions of PC. The PCs studied included didecanoyl PC (C10-PC), dilauroyl PC (C12-PC), dimyristoyl PC (C14-PC) and dipalmitoyl PC (C16-PC). PC incorporation of 10-15 mol% was achieved by incubation at 37 degrees C for 0.5-24 h. Control cells incubated in saline alone showed a progressive reduction in endogenous polyunsaturated acyl chain content. Incubation with C10-PC and C16-PC was associated with reductions in membrane cholesterol. Experiments were performed with mixtures of PC and cholesterol in order to minimise this effect. Short-chain PC incorporation was associated with increases in intracellular Na+ and reduced intracellular K+ concentrations. Sodium pump activity was measured as the ouabain-sensitive rate of 86Rb+ influx and was significantly reduced by all PCs tested; mean reductions were 13-30%. These results confirm that the sodium pump in situ is sensitive to lipid acyl chain composition.
Dwight
J F
JF
Department of Medicine, King's College School of Medicine and Dentistry, London, UK.
Hendry
B M
BM
D002784:Cholesterol / Q000097:blood; D004573:Electrolytes / Q000097:blood; D004910:Erythrocyte Membrane / Q000201:enzymology / Q000378:metabolism*; D004912:Erythrocytes / Q000201:enzymology / Q000378:metabolism; D006400:Hematocrit; D006801:Humans; D066298:In Vitro Techniques; D010713:Phosphatidylcholines / Q000097:blood; D010743:Phospholipids / Q000097:blood*; D012414:Rubidium Radioisotopes; D000254:Sodium-Potassium-Exchanging ATPase / Q000097:blood*
D004573:Electrolytes; D010713:Phosphatidylcholines; D010743:Phospholipids; D012414:Rubidium Radioisotopes; D002784:Cholesterol; D000254:Sodium-Potassium-Exchanging ATPase