Syngeneic pancreatic islet transplantation reverses endothelial dysfunction in experimental diabetes.
Diabetes is known to cause impaired endothelium-dependent relaxation of blood vessels. The purpose of this study was to determine whether this endothelial dysfunction is a permanent defect or is reversible after acute arginine supplementation in vitro or by surgical intervention in vivo using syngeneic pancreatic islet transplantation. Lewis rats were injected with streptozotocin to induce diabetes and were studied either 8 or 12 weeks later. Another group received syngeneic islets via intraportal injection at 8 weeks of diabetes and were allowed to become euglycemic for 4 weeks before study. Thoracic aortic rings were tethered in isolated muscle baths, contracted with a submaximal concentration of norepinephrine, and challenged with either the endothelium-dependent vasodilator acetylcholine or the endothelium-independent vasodilator nitroglycerin. Relaxation to acetylcholine (but not nitroglycerin) was reduced in both 8- and 12-week diabetic rings compared with age-matched control rings. Preincubation of diabetic rings in vitro with L-arginine (but not D-arginine) restored relaxation to acetylcholine to normal to rings from 8-week but not 12-week diabetic animals. Plasma basic amino acids (arginine, lysine, and histidine) were reduced by diabetes, whereas other neutral or acidic amino acids were unchanged (phenylalanine, proline, and glutamate), reduced (serine, cysteine, threonine, tyrosine, tryptophan, and aspartate), or elevated (isoleucine, leucine, and valine). Islet transplantation restored to normal the changes in plasma amino acids. Elevation in blood glucose and total glycosylated hemoglobin in diabetic animals was normalized after islet transplantation. Furthermore, islet transplantation completely restored the defective endothelium-dependent relaxation to acetylcholine in diabetic rings.(ABSTRACT TRUNCATED AT 250 WORDS)
Pieper
G M
GM
Department of Transplant Surgery, Medical College of Wisconsin, Milwaukee 52336, USA.
Jordan
M
M
Adams
M B
MB
Roza
A M
AM
D000109:Acetylcholine / Q000494:pharmacology; D000596:Amino Acids / Q000097:blood; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology* / Q000601:surgery*; D004730:Endothelium, Vascular / Q000502:physiology / Q000503:physiopathology*; D006442:Glycated Hemoglobin / Q000378:metabolism; D066298:In Vitro Techniques; D016381:Islets of Langerhans Transplantation; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology*; D005996:Nitroglycerin / Q000494:pharmacology*; D051381:Rats; D011917:Rats, Inbred Lew; D012016:Reference Values; D013997:Time Factors; D014185:Transplantation, Isogeneic; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
D000109:Acetylcholine; D000596:Amino Acids; D001786:Blood Glucose; D006442:Glycated Hemoglobin; D005996:Nitroglycerin