Effects of prolonged oral supplementation with L-arginine on blood pressure and nitric oxide synthesis in preeclampsia

Background Several lines of evidence point to the dysfunction of the endothelial. L-arginine NO system in preeclampsia. We investigated the influence of dietary supplementation with. L-arginine on blood pressure and biochemical measures of NO production in women with preeclampsia in prospective, randomized, placebo-controlled study. Design The 61 preeclamptic women on a standardized low nitrate diet received orally 3 g of. L-arginine ( n = 30) or placebo ( n = 31) daily for 3 weeks as a supplement to standard therapy. The differences between the two groups in systolic (SBP), diastolic (DBP) and mean arterial blood pressures ( MAP) as well as in plasma levels of selected aminoacids, plasma concentrations of nitrates/nitrites (NOx) and in 24-h urine NOx excretion were determined. Results After 3 weeks of treatment, values of SBP, DPB and MAP were significantly lower in the group taking. L-arginine as compared with the placebo group (SBP: 134.2 +/- 2.9 vs. 143.1 +/- 2.8; DBP: 81.6 +/- 1.7 vs. 86.5 +/- 0.9; MAP: 101.8 +/- 1.5 vs. 108.0 +/- 1.2 mmHg, P < 0.01). Importantly, treatment with exogenous L-arginine significantly elevated 24-h urinary excretion of NOx and mean plasma levels of L-citrulline. Exogenous L-arginine did not influence plasma concentrations of L-arginine, L-ornithine and methylated arginines ( ADMA, SDMA, L-NMMA). Conclusions We conclude that in women with preeclampsia, prolonged dietary supplementation with L-arginine significantly decreased blood pressure through increased endothelial synthesis and/or bioavailability of NO. It is tempting to speculate that the supplementary treatment with L-arginine may represent a new, safe and efficient strategy to improve the function of the endothelium in preeclampsia.