Luminal thrombus disrupts nitric oxide-dependent endothelial physiology.
BACKGROUND
The goals of this study were: (1) to develop a large animal model to study endothelial function, and (2) to determine if arterial thrombosis induces endothelial dysfunction in vivo.


METHODS
Surgical exposure of the porcine iliac and femoral arteries was performed. Normal porcine arteries were compared with arteries subjected to 90 min of arterial thrombosis. External iliac artery (EIA) luminal diameters were measured using M- and B-mode duplex ultrasound. Endothelium-dependent relaxation (EDR) and endothelium-independent relaxation (EIR) were measured using acetylcholine (ACh) and sodium nitroprusside (NTP), respectively. Endothelial integrity was determined by factor VIII immunohistochemistry (F8) and scanning electron microscopy (SEM). Nitric oxide levels were determined using a chemiluminescence assay of nitrite/nitrate metabolites (NO(x)). Continuous variables were analyzed using the two-tailed Student t test.


RESULTS
Control artery EDR was 80 +/- 7.1% (+/- SE), while arteries exposed to luminal thrombus for 90 min had an EDR of 55.2 +/- 5.7% (ACh = 15 microg/min, n = 11, P = 0.0231). EIR was preserved in normal and thrombosis groups with uniform response to NTP (4.92 +/- 0.1 cm vs 5.07 +/- 0.42 cm, P = 0.76). F8 staining identified endothelium in all groups. SEM analysis revealed an intact monolayer of endothelium after thrombosis. Local NO(x) levels were 17.3% lower after 90 min of thrombosis (49.3 microM vs 40.8 microM, n = 16, P < 0.001).


CONCLUSIONS
Luminal thrombus induces arterial dysfunction acutely without causing endothelial cell loss. EIR remains unaffected, indicating normal smooth muscle cell function. NO(x) levels suggest that nitric oxide levels are decreased acutely after thrombosis. The development of this porcine large animal model allows the in vivo study of vasospasm and alternative thrombolytic regimens.
Davis
Michael R
MR
Vascular Surgery, Wilford Hall Medical Center, Lackland Air Force Base, Texas 78236, USA.
Ortegon
Delio P
DP
Clouse
William D
WD
Kerby
Jeffrey D
JD
DeCaprio
Jeffrey D
JD
Chiou
Andy
A
Hagino
Ryan T
RT
Kashyap
Vikram S
VS
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005169:Factor VIII / Q000032:analysis; D005260:Female; D005263:Femoral Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D007083:Iliac Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D007150:Immunohistochemistry; D008163:Luminescent Measurements; D008855:Microscopy, Electron, Scanning; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000503:physiopathology; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000032:analysis / Q000494:pharmacology*; D009573:Nitrites / Q000378:metabolism; D009599:Nitroprusside / Q000494:pharmacology; D013552:Swine; D013927:Thrombosis / Q000503:physiopathology*; D014463:Ultrasonography
D009566:Nitrates; D009573:Nitrites; D009599:Nitroprusside; D009569:Nitric Oxide; D005169:Factor VIII; D000109:Acetylcholine