Diabetes, Vol 38, Issue 7 825-831, Copyright © 1989 by American Diabetes Association
Membrane lipid alterations and Na+-pumping activity in erythrocytes from IDDM and NIDDM subjects
P Baldini, S Incerpi, S Lambert-Gardini, A Spinedi and P Luly
Department of Biology, University of Rome Tor Vergata, Italy.
The Na+-pumping activity of the erythrocyte plasma membrane in diabetic
subjects was studied together with the lipid composition. Insulin-dependent
diabetes mellitus (IDDM) patients (n = 25) were divided into young (28.1
+/- 7.4 yr old, mean +/- SD; n = 16) and old (7.17 +/- 9.8 yr old; n = 10)
subjects; the age of non-insulin-dependent (NIDDM) patients was 70.7 +/-
11.5 yr (n = 10). The Na+-pumping activity, estimated from both
Na+-K+-ATPase and ouabain binding, was significantly decreased in IDDM and
NIDDM subjects, but its insulin sensitivity was retained only in young IDDM
subjects. The total cholesterol and phospholipid content of the erythrocyte
plasma membrane was lowered in IDDM subjects, and
cholesterol-to-phospholipid molar ratio was significantly decreased. In
NIDDM subjects the significant decreased of the two lipid components did
not alter their ratio. The analysis of major phospholipid components of
erythrocyte membranes revealed that only phosphatidylcholine is
significantly increased in young diabetic subjects. The fatty acid
composition of major phospholipid classes was significantly altered in all
cases: the unsaturation index appeared to be increased in
phosphatidylserine and sphingomyelin for both IDDM and NIDDM subjects and
was also increased in phosphatidylcholine in the latter group.