Molecular defects in sarcolemmal glycerophospholipid subclasses in diabetic cardiomyopathy

Although still scarcely studied, the phospholipid component of the cell mem brane is of absolute importance for cell function. Experimental evidence in dicates that individual molecular species of a given phospholipid can influ ence specific membrane functions. We have examined the changes in molecular species of diacyl and alkenylacyl choline/ethanolamine glycerophospholipid subclasses and those of phosphatidylserine in purified cardiac sarcolemma of healthy and streptozotocin-induced insulin dependent diabetic rats witho ut or with insulin treatment. The relative content of plasmalogens increase d in all the phospholipid classes of diabetic sarcolemma under study. Phosp hatidylcholine and phosphatidylethanolamine were mostly enriched with molec ular species containing linoleic acid in sn-2 position and deprived of the molecular species containing arachidonic acid. The molecular species of pho sphatidylserine containing either arachidonic or docosahexaenoic acid were less abundant in membranes from diabetic rats than in membranes from contro ls. Insulin treatment of diabetic rats restored the species profile of phos phatidylethanolamine and overcorrected the changes in molecular species of phosphatidylcholine, The results suggest that the high sarcolemmal level of plasmalogens and the abnormal molecular species of glycerophospholipids ma y be critical for the membrane dysfunction and defective contractility of t he diabetic heart. (C) 2000 Academic Press.