Serum and urine nitrate and nitrite are not reliable indicators of intrathecal nitric oxide production in acute brain injury

Rejdak, K; Petzold, A; Sharpe, M.A; Smith, M; Keir, G; Stelmasiak, Z; Thompson, E.J; Giovannoni, G

doi:10.1016/S0022-510X(02)00412-4

« Previous Next »Journal of the Neurological Sciences
Volume 208, Issue 1 , Pages 1-7, 15 April 2003

Serum and urine nitrate and nitrite are not reliable indicators of intrathecal nitric oxide production in acute brain injury

K Rejdak
- Department of Neuroinflammation, Institute of Neurology, Queen Square, London WC1N 3BG, UK
- Department of Neurology, Medical University, Lublin, Poland
A Petzold
- Department of Neuroinflammation, Institute of Neurology, Queen Square, London WC1N 3BG, UK
M.A Sharpe
- Department of Molecular Pathogenesis, Institute of Neurology, Queen Square, London, UK
M Smith
- Surgical Intensive Care Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
G Keir
- Department of Neuroinflammation, Institute of Neurology, Queen Square, London WC1N 3BG, UK
Z Stelmasiak
- Department of Neurology, Medical University, Lublin, Poland
E.J Thompson
- Corresponding author. Tel.: +44-207-837-3611; fax: +44-207-837-8553.
- Department of Neuroinflammation, Institute of Neurology, Queen Square, London WC1N 3BG, UK
G Giovannoni
- Department of Neuroinflammation, Institute of Neurology, Queen Square, London WC1N 3BG, UK

Received 21 March 2002; received in revised form 16 October 2002; accepted 16 October 2002.

Abstract

This study examined the correlation between nitric oxide (NO) metabolites in the three major body fluid compartments and assessed performance of newly described vanadium-based assay for simultaneous detection of nitrite and nitrate (NO_x) in human samples. Vanadium reduces nitrate to nitrite, which can be measured after a colorimetric reaction with Griess reagents.

Cisternal cerebro spinal fluid (CSF), serum and urine samples from 10 patients with acute brain injury (ABI) were compared to control subjects. Significantly higher CSF NO_x levels were found in brain injury patients compared to control patients (19.7±13.7 vs. 6.5±2.3 μM; p=0.01), which persisted for 10-day period of observation. The serum and urine levels of NO_x on admission were not statistically different (42.8±28.2 μM; 584.1±337.8 μmol/g Cr, respectively) from controls (36.8±14.8 μM; 819.7±356.0 μmol/g Cr), but tended to decrease during the disease course reaching the lowest level on day 6 (serum: 19.3±8.4 μM, urine: 300.4±111.9 μmol/g Cr). CSF levels of NO_x correlated moderately with those in serum (p=0.001, R=0.5). Serum NO_x concentrations correlated weakly with urine levels (p=0.04, R=0.3). There was no significant correlation between CSF NO_x and urine NO_x levels.

In conclusion, patients suffering brain injury had increased NO_x concentrations in CSF, which remained independent from other body fluid compartments. Serum and urinary NO_x levels cannot be used as a reliable index to assess intrathecal NO production.

Keywords: Nitric oxide, Nitrate, Nitrite, Body fluids, Assay, Vanadium