L-Arginine improves endothelial vasoreactivity and reduces thrombogenicity after thrombolysis in experimental deep venous thrombosis

Purpose: Nitric oxide (NO) is important in regulation of platelet aggregation, endothelial function, and intravascular thrombosis. The purposes of this study were to assess the effect of thrombolysis on endothelial function in a porcine model of deep venous thrombosis (DVT) and to evaluate the effect of NO precursor L-arginine on endothelial function after thrombolytic therapy. Methods: DVT was created in bilateral iliac veins by deploying a self-expanding stent-graft that incorporated an intraluminal stenosis, from a groin approach. Five pigs underwent sham operation. After 7 days of DVT, animals were randomized to three groups: saline pulse-spray (saline group, n = 5), thrombolytic pulse-spray with tissue plasminogen activator (alteplase, 8 mg; t-PA group, n = 5), and thrombolytic pulse-spray plus intravenous L-arginine (20 mmol/L; arginine group, n = 5). At 2 weeks iliac vein patency was evaluated at venography and intravascular ultrasound scanning. NO level was determined with a chemiluminescent assay of the nitrite and nitrate metabolites (NO _x). Thrombogenicity was evaluated with radiolabeled platelet and fibrin deposition. Veins were harvested and evaluated with light microscopy and scanning electron microscopy. Endothelial function was evaluated with organ chamber analysis. Results: All iliac veins remained patent at 2 weeks. The luminal areas in the sham, saline, t-PA, and arginine groups were 53 ± 23 mm², 14 ± 11 mm², 34 ± 19 mm ², and 42 ± 21 mm², respectively. No difference in endothelial cell structure was observed between the three treatment groups at light microscopy or scanning electron microscopy. Although no difference in fibrin deposition was noted among the three treatment groups, decreased platelet deposition occurred in the arginine group compared with the saline or t-PA groups (P < .05). The arginine group showed greater endothelial-dependent relaxation compared with the t-PA or saline groups (73% ± 23% vs 49% ± 18% and 32% ± 21%; P < .05). Local NO_x level in the arginine group was correspondingly higher compared with the saline or t-PA groups (1.8 ± 0.3 μmol/L vs 0.3 ± 0.05 μmol/L and 0.2 ± 0.04 μmol/L; P < .05). Conclusions: NO precursor L-arginine supplementation enhances NO production at sites of venous thrombosis. Moreover, L-arginine preserves endothelial vasoreactivity and reduces platelet deposition after thrombolysis in iliac DVT. These data suggest that L-arginine may preserve endothelial function after thrombolysis and may reduce the likelihood of postthrombotic syndrome.