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Acute exudative inflammation and nasally exhaled nitric oxide are two independent phenomena
Anders Cervin1, Lennart Greiff, Sven Lindberg
1School of Biomolecular and Biomedical Sciences, Griffith University Brisbane, Australia. anders.cervin@onh.lu.se
Background:
Increased levels of nitric oxide (NO) and the exudations of plasma proteins to the airway lumen have both been considered characteristics of airway inflammation. The aim of the present study was to investigate a possible relationship between nasal NO concentrations and acutely induced exudative inflammation of the nasal mucosa.
Methods:
Twelve healthy non-allergic subjects participated. Nasal challenges with saline, histamine 40 microg/ml (H1), histamine 400 microg/ml (H2), oxymethazoline, 0.25 mg/ml (OXY), and a combination of oxymethazoline 0.25 mg/ml and histamine 800 microg/ml (OXYH), were performed on separate occasions. Exhaled NO was measured after each challenge, and alpha(2)-macroglobulin (as a marker of plasma exudation) was measured in nasal lavage fluids after the H1 and H2 challenges.
Results:
The mean baseline NO in all measurements was 164 plus minus 10.3 ppb. Saline and H1 challenge did not change NO and alpha(2)-macroglobulin levels. H2 challenge showed a tendency to reduce NO levels, and the most pronounced decrease was seen after 10 min (-36.3 +/- 16.3%, p = 0.07). This reduction was sustained throughout the registration period. Simultaneously with the decrease in NO, alpha(2)-macroglobulin levels were increased significantly. OXY challenge alone reduced NO significantly throughout the whole registration period. Maximum decrease was seen at 40 min (-21.3 plus minus 3.4%, p = 0.03). The OXYH challenge also reduced NO, with a maximal reduction recorded at 10 min (-29.4 +/- 6.4%, p = 0.03). The reduction of NO was sustained throughout the registration period (p < 0.01).
Conclusion:
Histamine 400 microg/ml induced a prompt plasma exudation response whereas a decrease in nasal NO was registered, suggesting that these two events are not necessarily linked. Furthermore it was shown that the vasoconstrictor oxymethazoline reduced nasal NO, which could be related to reduced mucosal blood flow, whereas the reduction of nasal NO after histamine challenge remains to be elucidated.