LONG-TERM ORAL-ADMINISTRATION OF L-ARGININE ENHANCES ENDOTHELIUM-DEPENDENT VASORELAXATION AND INHIBITS NEOINTIMAL THICKENING AFTER ENDOTHELIAL DENUDATION IN RATS

Objective. To further prove the hypothesis that local decrease of nitr ic oxide (NO) synthesis and/or its activity might be critically import ant in the disturbance of vascular homeostasis after vascular injuries . Methods. Intimal thickening model induced by air-drying denudation o f rat right common carotid artery was performed to evaluate the effect s of long-term oral administration of L-arginine on neointimal thicken ing and acetylcholine-induced endothelium-dependent vasorelaxation (ED R) by histomorphometric and functional studies. Results, Reductions in EDR function persisted and simultaneously developed prominent neointi mal thickening by 14 days after denudation. Long-term oral supplementa tion of L-arginine (1 g/kg/day) significantly enhanced EDR from 43.5%/- 12..35% to 68.8%+/- 9.0% (n=10, P<0.001) and reduced neointimal thi ckening from 62.45 mu m +/- 11.26 mu m to 21.45 mu m +/- 6.34 mu m (n = 10, p<0.001) as compared with each control animals. Conclusions, Thi s study shows that oral administration of L-arginine significantly inh ibits neointimal thickening and preserves NO-mediated EDR in experimen tal endothelial denudation, suggesting an important role for L-arginin e, NO pathway in the regulation of vascular homeostasis after endothel ial injury which might bt: salutary in prevention restenosis after cor onary angioplasty.