title: L-arginine levels in blood as a marker of nitric oxide-mediated brain damage in acute stroke: a clinical and experimental study.
abstract: There are no useful markers in blood of nitric oxide (NO)-mediated brain damage. Because l-arginine (l-arg) is the only known substrate for NO generation, the authors investigated the plasma profile of l-arg after cerebral ischemia, and the relationship of L-arg concentrations in blood with stroke outcome and infarct volume in a clinical and experimental study. l-Arg levels were determined with high-performance liquid chromatography in blood and CSF samples obtained on admission, and in blood 48 hours after inclusion, in 268 patients admitted with a hemispheric ischemic stroke lasting 8.2 +/- 5.9 hours. Infarct volume was measured by days 4 to 7 using computed tomography. Plasma l-arg profiles were analyzed in a separate group of 29 patients seen within 8 hours of onset (median, 4.5 hours) and in 24 male Fischer rats treated with subcutaneous vehicle or 20-mg/kg 1400W (a specific inducible NO synthase inhibitor) every 8 hours for 3 days after performing sham or permanent middle cerebral artery occlusion. Plasma l-arg concentrations decreased after the ischemic event, both in patients and rats, and peaked between 6 and 24 hours. In patients, there was a highly correlation between l-arg levels in CSF and plasma at 48 hours (r = 0.85, P<0.001). CSF and plasma l-arg concentrations negatively correlated with infarct volume (r = -0.40 and r = -0.35, respectively, P<0.001), and were significantly lower in patients with early neurologic deterioration and in those with poor outcome (Barthel index <85) at 90 days (P<0.001). In rats, the administration of 1400W resulted in a 55% significant reduction of infarct volume measured 72 hours after permanent middle cerebral artery occlusion, an effect that correlated with the inhibition caused by 1400W on the ischemia-induced decrease of plasma l-arg concentrations at 6 to 24 hours after the onset of the ischemia. Taken together, these data indicate that determination of l-arg levels in blood might be useful to evaluate the neurotoxic effects of NO generation. These findings might be helpful to guide future neuroprotective strategies in patients with ischemic stroke.
authors.affiliation: Department of Neurology, Hospital Doctor Josep Trueta, Girona, Spain.
authors.forename: Arola
authors.initials: A
authors.lastname: Armengou
authors.forename: Olivia
authors.initials: O
authors.lastname: Hurtado
authors.forename: Rogelio
authors.initials: R
authors.lastname: Leira
authors.forename: María
authors.initials: M
authors.lastname: Obón
authors.forename: Carlos
authors.initials: C
authors.lastname: Pascual
authors.forename: María A
authors.initials: MA
authors.lastname: Moro
authors.forename: Ignacio
authors.initials: I
authors.lastname: Lizasoain
authors.forename: José
authors.initials: J
authors.lastname: Castillo
authors.forename: Antoni
authors.initials: A
authors.lastname: Dávalos
mesh_terms: D000208:Acute Disease; D000368:Aged; D000818:Animals; D001120:Arginine / Q000097:blood* / Q000134:cerebrospinal fluid; D015415:Biomarkers / Q000097:blood* / Q000134:cerebrospinal fluid; D001922:Brain Abscess / Q000097:blood; D002853:Chromatography, Liquid; D005260:Female; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052247:Nitric Oxide Synthase Type II; D051381:Rats; D011916:Rats, Inbred F344; D020521:Stroke / Q000097:blood*
chemical_list: D015415:Biomarkers; D009569:Nitric Oxide; D001120:Arginine; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat