Alterations in Ca2+ binding by and composition of the cardiac sarcolemmal membrane in chronic diabetes.
Chronic streptozotocin-induced diabetes in rats was associated with a significant loss in the ability of isolated cardiac sarcolemmal membranes to bind Ca2+. Administration of insulin to the diabetic rats normalized the sarcolemmal Ca2+ binding capacity. The content of sialic acid residues, which are considered to represent a superficial Ca2+ pool in sarcolemma, was decreased in preparations from diabetic rats, and this change also was reversible upon insulin treatment of the diabetic rats. Treatment of sarcolemma with neuraminidase decreased Ca2+ binding by 37% in control preparations but had no effect on diabetic preparations. Diphosphatidylglycerol content was decreased but other acidic phospholipids such as phosphatidylinositol and phosphatidylserine, which also bind Ca2+, were not altered during diabetes. An increase in lysophosphatidylcholine and a decrease in phosphatidylethanolamine contents were observed in membranes isolated from diabetic rats. These results suggest that some alterations occur in Ca2+ binding and composition of heart sarcolemma in chronically diabetic rats and may provide further insight into the pathogenesis of diabetic cardiomyopathy.
D000818:Animals; D001835:Body Weight; D002118:Calcium / Q000378:metabolism*; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D006352:Heart Ventricles / Q000503:physiopathology; D007425:Intracellular Membranes / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D009439:Neuraminidase / Q000378:metabolism*; D009929:Organ Size; D010743:Phospholipids / Q000032:analysis; D011485:Protein Binding; D051381:Rats; D011919:Rats, Inbred Strains; D012508:Sarcolemma / Q000378:metabolism*; D012799:Sialyltransferases / Q000378:metabolism
D010743:Phospholipids; D012799:Sialyltransferases; D009439:Neuraminidase; D002118:Calcium