Lipoic acid supplementation has been found to be beneficial in preventing neurovascular abnormalities in
diabetic neuropathy. Insufficient (Na(+) + K(+))-
ATPase activity has been suggested as a contributing factor in the development of
diabetic neuropathy. This study was undertaken to test the hypothesis that
lipoic acid reduces lipid peroxidation and glycosylation and can increase the (Na(+) + K(+))- and Ca(++)-
ATPase activities in high
glucose-exposed red blood cells (RBC). Washed normal human RBC were treated with normal (6 mM) and high
glucose concentrations (45 mM) with 0-0.2 mM
lipoic acid (mixture of S and R sterioisomers) in a shaking water bath at 37 degrees C for 24 h. There was a significant stimulation of
glucose consumption by RBC in the presence of
lipoic acid both in normal and high
glucose-treated RBC.
Lipoic acid significantly lowered the level of
glycated hemoglobin (GHb) and lipid peroxidation in RBC exposed to high
glucose concentrations. High
glucose treatment significantly lowered the activities of (Na(+) + K(+))- and Ca(++)-
ATPases of RBC membranes.
Lipoic acid addition significantly blocked the reduction in activities of (Na(+) + K(+))- and Ca(++)-
ATPases in high
glucose- treated RBC. There were no differences in lipid peroxidation, GHb and (Na(+) + K(+))- and Ca(++)-
ATPase activity levels in normal
glucose-treated RBC with and without
lipoic acid. Thus,
lipoic acid can lower lipid peroxidation and protein glycosylation, and increase (Na(+) + K(+))- and Ca(++)-
ATPase activities in high-
glucose exposed RBC, which provides a potential mechanism by which
lipoic acid may delay or inhibit the development of neuropathy in diabetes.