Diabetes mellitus induces red blood cell plasma membrane alterations possibly affecting the aging process

Various alterations of red blood cell (RBC) plasma membrane appear both in diabetes mellitus and during the physiological aging process. Diabetes mellitus decreases RBC life-span; therefore, it may change the plasma membrane by acting through its effect on the aging process. In order to clarify the issue, RBCs from normal subjects and insulin-dependent diabetic patients were fractionated in five subpopulations of different mean age (fraction 1: early young RBC, fraction 5: mature RBC). Thereafter, plasma membranes were prepared and enzymatic activities, membrane fluidity and lipid peroxidation were evaluated. NA+, K(+)-ATPase activity decreased during aging and it was higher in all RBC subpopulations from normal subjects in comparison to diabetic patients. Next, lipid peroxidation and fluidity increased during aging in both the study groups; in this case, however, in all subpopulations, except for that from fraction 1, RBCs from diabetic patients showed higher membrane fluidity and lipid peroxidation in comparison to normal subjects. Data herein reported suggest that diabetes mellitus affects the plasma membrane independently of (lipid peroxidation and fluidity) or dependently on (Na+, K(+)-ATPase) its effect on aging. In the case of lipid peroxidation and fluidity diabetes mellitus seems to affect the membrane by decreasing RBC life span, whereas in the case of Na+K(+)-ATPase it seems to alter this enzymatic activity which in turn might affect RBC aging. Acetylcholinesterase activity decreased during aging in RBCs from normal subjects, but it increased in RBCs from diabetic patients; RBC subpopulation from fraction 1, on the other hand, showed similar values in normal subjects and diabetic patients. In this case the effect of diabetes mellitus appears only during aging.