Fatty acid composition of phospholipids and neutral lipids from human diabetic small arteries and veins by a new TLC method

It has been suggested that lipid peroxidation of polyunsaturated fatty acid s (PUFA) may play a role in the pathogenesis of diabetic complications. To test this hypothesis, we aimed to compare PUFA composition of small arterie s and veins (< 500 mu m diameter) obtained from diabetic or non-diabetic Gu adeloupean patients undergoing arterio-venous shunt surgery before renal di alysis. Small forearm subcutaneous vessels were analysed by a new TLC method which involved inclusion of vascular biopies directly in alveoles made in the TLC gel and lyophilization onto the plate. The TLC plate was then chromatograp hed and lipids were both extracted and eluted during this step. Fatty acid composition of phospholipid and neutral lipid fractions were determined. Si milar fatty acid composition was obtained for arteries and veins from diabe tic or non-diabetic subjects. In phospholipids from diabetic vessels, major changes consisted of a 20% decrease of arachidonic acid (20:4 n-6), a 40% decrease of its elongation product 22:4 n-6 and 30% increase of 18:2 n-6. I n neutral lipids, 20:4 n-6 was also diminished by 60% whereas oleic acid in creased by 15%. This loss of arachidonic acid in small diabetic vessels suggests impaired D elta 6-desaturase forming 20:4 n-6 or alternatively increased peroxide form ation, in the vascular wall of smalt vessels in diabetic patients.