Changes of membrane fluidity in erythrocytes of obese children: a spin label study

Red blood cells depend on circulating lipoproteins for the turnover of membrane phospholipids. Thus abnormalities in lipid and lipoprotein metabolism are frequently associated with changes in composition and fluidity of erythrocyte membranes. Using the electron spin resonance technique we studied the physical state of erythrocyte membranes from 15 obese children with a body mass index ranging from 22.8 to 34 kg . m-2 and slight alterations of plasma lipids. The spin labels used, 5-doxylstearate and 16-doxylstearate, have shown an increase of the order parameter and of the correlation time, respectively. These observations indicate a decrease of fluidity at the surface and in the hydrophobic core of erythrocyte membranes from obese subjects. The results are statistically significant and they are discussed in relation to clinical aspects of childhood obesity. Studies on erythrocyte membrane molecular organization could represent a sensitive way to find out small metabolic alterations hardly detectable with compositional studies.