Low nitric oxide concentrations in exhaled gas and nasal airways of mammals without paranasal sinuses

To investigatewhether relevant levels of nasal nitric oxide (NO) are produced in theabsence of paranasal sinuses, we studied 17 healthy baboons, mammalswithout any paranasal sinuses. The animals were anesthetized withketamine hydrochloride and breathed spontaneously. While the baboonsbreathed through a face mask (mouths closed) connected to a respirator,NO concentrations in exhaled gas were sampled from the expiratory limband analyzed by chemiluminescence. While the animals were breathingambient air, nasal gas was sampled via a thin plastic tube and analyzed for NO concentrations by chemiluminescence. Mean NO concentration inthe exhaled gas was 1.00 ± 0.59 parts/billion, and NO release was4.28 ± 2.72 nl/min. A NO concentration of 4.79 ± 2.08 parts/billion was found in the nasal gas (NO release: 7.18 ± 3.13 nl/min). An age-dependent increase in nasal NO levelswas not observed. Exhaled and nasal NO concentrations in baboons weremarkedly lower than in mammals with paranasal sinuses, suggesting thatparanasal sinuses might be an anatomic requirement for production ofrelevant nasal NO levels.