Effects of dietary L-arginine on structure and function of flow-restricted vein grafts.
OBJECTIVE
Experiments were designed to determine effects of dietary supplementation with L -arginine on structure and function of flow-restricted vein grafts.


METHODS
Saphenous veins were placed as bilateral interposition grafts in femoral arteries of two groups of adult male mongrel dogs; one group was maintained on a normal diet (control), the other group supplemented with L -arginine (200 mg/kg per day) beginning 1 week before surgery. In each dog, flow was reduced by 50% in one graft by placing an adjustable clamp on the artery distal to the distal anastomosis. Plasma amino acids and oxidized products of nitric oxide (NO(x )) were measured before and after L -arginine feeding. At postoperative week 4, grafts were removed and prepared for organ chamber studies to determine functions of the endothelium or smooth muscle and for histology.


RESULTS
Plasma L -arginine increased within 3 hours after feeding and increased from 141 +/- 8 nmol/mL to 169 +/- 11 nmol/mL (n = 6) after 5 weeks of supplementation. Plasma ornithine and citrulline paralleled arginine, whereas circulating NO(x ) was unchanged. Maximal contractions to 60 mmol/L KCl were reduced in grafts from L -arginine-fed dogs. Endothelium-dependent relaxations to the calcium ionophore A23187 and relaxations of the smooth muscle NO were reduced in grafts from L -arginine-fed dogs. Neointimal hyperplasia was increased in grafts with reduced flow and not affected by arginine feeding.


CONCLUSIONS
Dietary supplementation with L -arginine did not increase plasma NO in dogs with peripheral vein grafts or increase endothelium-dependent relaxations in control or flow-restricted grafts. Therefore, dietary supplementation with L -arginine may not improve long-term functions of flow-restricted peripheral bypass grafts.
Landis
M E
ME
Department of Surgery, Mayo Foundation, Rochester, MN, USA.
Ray
E C
EC
Gloviczki
P
P
Miller
V M
VM
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000596:Amino Acids / Q000097:blood; D000818:Animals; D001120:Arginine / Q000008:administration & dosage* / Q000097:blood / Q000494:pharmacology; D001783:Blood Flow Velocity; D000068438:Brimonidine Tartrate; D000001:Calcimycin / Q000494:pharmacology; D003251:Constriction, Pathologic; D019587:Dietary Supplements; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D005263:Femoral Artery / Q000601:surgery; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D009569:Nitric Oxide / Q000097:blood / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D012501:Saphenous Vein / Q000187:drug effects / Q000473:pathology / Q000502:physiology / Q000637:transplantation*; D014654:Vascular Patency
D000316:Adrenergic alpha-Agonists; D000596:Amino Acids; D011810:Quinoxalines; D009569:Nitric Oxide; D000001:Calcimycin; D000068438:Brimonidine Tartrate; D001120:Arginine