ORAL L-ARGININE SUPPLEMENTATION AND CUTANEOUS VASCULAR-RESPONSES IN PATIENTS WITH PRIMARY RAYNAUDS-PHENOMENON

Objective. To assess the effects of oral L-arginine supplementation on cutaneous vascular responses in patients with primary Raynaud's pheno menon (RP). Methods. Double-blind, crossover comparison of placebo ver sus L-arginine (8 gm/day for 28 days), Cutaneous vascular responses in the fingers were assessed during iontophoresis of acetylcholine and s odium nitroprusside, which are endothelium-dependent and endothelium-i ndependent vasodilators, Results. In comparison with control subjects, patients with primary RP had diminished endothelium-dependent and -in dependent vasodilatation (P < 0.05, and P < 0.005, respectively, by an alysis of variance), At the 3 doses used, vascular responses to acetyl choline were reduced by 71%, 64%, and 63%, respectively, and responses to sodium nitroprusside were reduced by 67%, 73%, and 66%, respective ly, L-arginine had no significant effect on cutaneous vascular respons es to acetylcholine or sodium nitroprusside in control subjects or pat ients with primary RP. Conclusion. Reduced vasodilator ability in prim ary RP is unlikely to be due to an impairment in the L-arginine/nitric oxide pathway.