The Paranasal Sinuses as Reservoirs for Nitric Oxide

Objective --Nitric oxide (NO) is an important mediator and inflammatory marker in human upper airways. Enzymes responsible for NO production have been demonstrated both in the nose and in the paranasal sinuses, but NO levels in the sinuses are reported to be several times higher than those in the nose. It has been postulated that the paranasal sinuses may be the primary sites for NO production in the upper respiratory tract. The present study was designed to compare the NO levels sampled from the nose with those found in the paranasal sinuses. Material and methods --NO levels in the maxillary sinus and nose were determined using a continuous chemiluminescence measuring technique in seven healthy volunteers. Results --When NO was sampled, via a drainage tube inserted into the maxillary sinus, a transient peak in NO level was recorded. The maximal NO level (5,761 - 1,513 ppb; n = 7) was reached within 10 s and was followed by the establishment of a lower steady-state level (304 - 51 ppb). When NO was continuously sampled from the nose a steady-state level, similar to that found in the sinus, was immediately established (313 - 52 ppb). Conclusion --The data presented confirm previous findings of extremely high NO levels in the paranasal sinuses and suggest that these cavities may also function as reservoirs for NO.