Background and Aims:
Sodium nitrite is a major intravascular storage for nitric oxide. The conversion of nitrite to the active nitric oxide occurs mainly under hypoxic conditions to increase blood flow where it is needed the most. The use of nitrite is, therefore, being evaluated more and more widely to reduce the damage in conditions resulting in cerebral hypoxia, such as cardiac arrest, ischaemic stroke or subarachnoid haemorrhage (SAH). Nitrite increases the brain activity of certain patients with SAH. However, the effects of the nitrite on the brain of healthy individuals who presumably do not have cerebral hypoxia are still unknown. Here we performed a double-blind placebo-controlled crossover study to investigate the effects of nitrite on the healthy brain.

Methods:
Twenty-one healthy volunteers were recruited into the study. All participants received a continuous infusion of sodium nitrite (0.6mg/kg/h) on one occasion and placebo (sodium chloride) on another occasion. Electroencephalogram (EEG) was recorded before the start and during the infusion. We analysed the difference in the alpha-delta ratio of the EEG power spectrum during the nitrite and placebo infusions. 

Results:
When comparing the alpha-delta ratio during sodium nitrite and placebo infusions, we did not find any significant difference. 

Conclusions:
This lack of change in alpha-delta ratio emphasises the specificity of the brain’s response to nitrite after SAH. This difference could be because the sodium nitrite is converted to vasoactive nitric oxide in areas of hypoxia, and in the healthy brain there is no significant amount of conversion due to lack of hypoxia.

EFFECT OF NITRITE ON THE NEURAL ACTIVITY IN THE HEALTHY BRAIN