Effect of vein graft harvesting on endothelial nitric oxide synthase and nitric oxide production.
BACKGROUND
Although the saphenous vein is the most commonly used conduit for coronary artery bypass surgery occlusion rates are high, with more than 50% grafts failing within 10 years. Nitric oxide, a potent vasodilator, also inhibits platelet aggregation, thrombus formation and vascular smooth muscle cell proliferation, is implicated in various vascular pathologies, including graft failure.


METHODS
Saphenous veins were obtained from patients undergoing bypass surgery harvested by conventional methods and with minimal handling, using a "no-touch" technique. Tissue distribution and protein expression of endothelial nitric oxide synthase was compared using immunohistochemistry and Western blot analysis. Nitric oxide generation was assessed using the citrulline assay.


RESULTS
There was injury to conventional compared with no-touch vein segments, in particular to the lumenal endothelium and tunica adventitia. This injury was accompanied by an absence of endothelial nitric oxide synthase immunostaining at regions of endothelial denudation and damaged adventitial layer of conventional veins and a significant reduction (p < 0.05) in endothelial nitric oxide synthase protein expression. Furthermore, nitric oxide release from conventional tissue extracts was significantly (p < 0.05) lower than no-touch vein segments.


CONCLUSIONS
Our results show that there is a reduction in endothelial nitric oxide synthase and nitric oxide release in saphenous veins harvested by conventional surgical methods compared with those prepared atraumatically. These observations may influence graft performance.
Dashwood
Michael R
MR
Department of Clinical Biochemistry, Royal Free and University College Medical School, Pond Street, London, United Kingdom. mdashwood@rfc.ucl.ac.uk
Savage
Kay
K
Dooley
Audrey
A
Shi-Wen
Xu
X
Abraham
David J
DJ
Souza
Domingos S R
DS
D000368:Aged; D001026:Coronary Artery Bypass / Q000379:methods; D004730:Endothelium, Vascular / Q000378:metabolism*; D005260:Female; D006085:Graft Survival; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D012501:Saphenous Vein / Q000293:injuries / Q000378:metabolism* / Q000473:pathology / Q000637:transplantation*; D019737:Transplants; D014654:Vascular Patency
D009569:Nitric Oxide; D019001:Nitric Oxide Synthase