Background:Plasma levels of L-arginine have previously been evaluated in several studies to reveal either down- or up-regulation of the L-arginine/NO pathway in chronic uremia.Material/Methods:We studied L-arginine plasma levels along with intracellular neutrophil concentration and NO release by peripheral blood neutrophils in patients with chronic uremia.Results:The L-arginine plasma concentration was found to be significantly higher (64.4I12.0 Kmol/L) in chronic uremic patients (n=25) than in healthy controls (33.0?I10.0 Kmol/L; n=25). Neutrophil homogenate L-arginine levels were substantially increased in uremic patients (7.95?I1.10 nmol/108 cells) as compared with controls (5.22I0.46 nmol/108 cells). The in vitro release of NO by unstimulated neutrophils was lower in uremic patients (0.14?I0.05? Kmol•s–1) than in healthy persons (0.48I0.20 Kmol•s–1). The NO release after uremic neutrophil stimulation with 10–6 M fMLP was 21.42I2.13 Kmol•s–1, while after PMA it was 31.01I1.99 Kmol•s–1. NO release after normal neutrophil stimulation with 10–7 M fMLP was 19.52I2.32 Kmol•s–1, and after PMA was 28.63I3.06 Kmol•s–1.Conclusions:In chronic uremic patients plasma and neutrophil concentrations of L-arginine were significantly higher. However, there were no significant differences in NO release between normal and uremic neutrophils after stimulation. Our findings may have implications for the impact of the L-arginine-nitric oxide signaling pathway on the pathophysiological changes in the L-arginine: NO pathway seen in chronic uremia.

Keywords: Arginine - blood, Neutrophils - metabolism, Nitric Oxide - metabolism, Signal Transduction - physiology, Uremia - blood