Abstract
Objective: Nitric oxide (NO), which has a high affinity for oxyhemoglobin (OxyHb), regulates basal vascular tone and cerebral blood flow. We examined serial changes in the concentration of NO end products (NO2-/ NO3-) in the cerebrospinal fluid (CSF) and plasma from patients who had suffered aneurysmal subarachnoid hemorrhage (SAH), in order to investigate the relationship between NO2-/N3- concentration and cerebral vasospasm.
Methods: Nineteen patients (13 females and 6 males) with SAH who had undergone cisternal drainage were enrolled for this study. In 17 patients, CSF and plasma samples were taken for analysis of nitrite and nitrate levels after surgery. The Griess procedure was applied to measure nitrite and nitrate in the CSF and serum. Only nitrite and nitrate in the CSF were measured in the cases.
Results: The mean CSF nitrate concentration in the SAH patients was 8.6 ± 0.8 µmol/l, indicating statistically significant elevation compared with that of the control (5.9 ± 0.9 µmol/l). However, CSF nitrate in the SAH patients remained at low levels during days 4-7. The mean plasma nitrate was 16.1 ± 1.7 µmol/l, a significantly lower level than that of the control (41.5 ± 5.62 µmol/l). A positive correlation existed between the mean nitrate in CSF and in plasma, fitting the straight line (y=0.367x+2.653, R2=0.527). Five patients developed a serious vasospasm leading to poor outcome, but we could not detect any elevation of the nitrate level in sequential measurements.
Conclusion: The concentration of CSF nitrate in the patients with SAH decreased to a low level during days 4 to 7 and did not correlate with the onset of cerebral vasospasm. A likely explanation for this result was that the total amount of NO production in the brain decreased after SAH.
