Plasma levels of nitric oxide and stroke outcome

Abstract

Production of reactive oxygen species after cerebral blood flow disruption may enhance tissue damage through multiple molecular pathways. Changes in nitric oxide (NO) metabolism and oxidative stress status were investigated in 47 patients with ischemic stroke by measuring plasma nitric oxide (NO) and peroxynitrite (ONOO(-)) levels.A correlation was sought between these two parameters and i) baseline stroke severity based on the National Institute of Health stroke scale (NIHSS) and ii) neurological outcome in terms of NIHSS changes from entry (T(0)) to 30 days after symptom onset (T(1)). The control group consisted of 30 age- and sex-matched healthy subjects. Mean plasma levels of ONOO(-) (arbitrary fluorescence number +/- SD) were significantly higher in patients (7.70 +/- 1.71 vs 5.35 +/- 0.69, p < 0.001), whereas mean NO levels (nmol/mg protein) were significantly higher in controls (115.40 +/- 12.40 vs. 51.10 +/- 12.50, p < 0.001). Plasma ONOO(-) was significantly higher among patients with non-lacunar stroke (8.48 +/- 1.50 vs. 6.95 +/- 1.58 in those with lacunar stroke; p = 0.001), whereas NO levels were significantly higher among lacunar stroke patients (60.00 +/- 7.86, vs. 41.77 +/- 9.29 in patients with nonlacunar stroke; p < 0.001). Nitric oxide plasma levels were also associated with an unfavorable evolution in non-lacunar stroke, since a 10 unit increase in NO predicted a 1 point reduction in the NIHSS score at T1. Findings show that changes in NO metabolism may be considered as markers of brain injury in patients with ischemic stroke. Further work is needed to establish whether the amount of biochemical changes related to oxidative stress may influence outcome in these patients.