Does periadventitial fat-derived nitric oxide play a role in improved saphenous vein graft patency in patients undergoing coronary artery bypass surgery?
OBJECTIVE
The saphenous vein is commonly used for coronary artery bypass surgery but its patency is poor. Vascular damage occurs during conventional surgery. However, patency improves when the graft is harvested with minimal surgical trauma, partly due to preservation of vascular endothelial nitric oxide synthase (eNOS) and tissue sources of nitric oxide (NO), a factor possessing both dilatory and anti-proliferative properties. Apart from these grafts exhibiting an intact luminal endothelium they are harvested complete with a surrounding cushion of tissue, much of which is fat.


METHODS
Immunostaining for eNOS was performed on vein graft sections and reverse-transcriptase polymerase chain reaction and Western blotting were used to identify eNOS mRNA and protein. NO synthase activity was measured using the citrulline assay.


RESULTS
Immunohistochemistry identified eNOS staining of vein graft segments, including dense staining of the cushion of perivascular fat and associated structures surrounding the vein. eNOS protein was confirmed in both the vein and surrounding fat by Western blot analysis. Using the citrulline assay, the perivascular fat and underlying vein possessed comparable NO synthase activity.


CONCLUSIONS
Our observations suggest that perivascular fat-derived NO plays a beneficial role in saphenous veins harvested atraumatically and used as grafts in patients undergoing coronary artery bypass surgery.
Dashwood
Michael R
MR
Department of Clinical Biochemistry, Royal Free and University College Medical School, London, UK. m.dashwood@medsch.ucl.ac.uk
Dooley
Audrey
A
Shi-Wen
Xu
X
Abraham
David J
DJ
Souza
Domingos S R
DS
D000273:Adipose Tissue / Q000378:metabolism* / Q000637:transplantation; D015153:Blotting, Western; D001026:Coronary Artery Bypass; D006801:Humans; D007150:Immunohistochemistry; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012501:Saphenous Vein / Q000378:metabolism* / Q000503:physiopathology / Q000637:transplantation; D020858:Tissue and Organ Harvesting / Q000379:methods*; D014654:Vascular Patency
D012333:RNA, Messenger; D009569:Nitric Oxide; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III