Does nasal nitric oxide come from the sinuses?

Objective: The purpose of this study was to assess nitric oxide (NO) output by the nose and sinuses. Method: In one volunteer, the osteomeatal complex and sphenoethmoidal reces s were occluded to isolate the nose from the sinuses. The antrum and fronta l sinus were each punctured by two catheters and irrigated with air at cons tant flow. Nitric oxide output and its rate of accumulation in the absence of air flow were measured in each sinus and in the adjacent nasal cavity. Results: Prior to ostial occlusion, NO output in the nose was 96 nL/min. It decreased by 12% after blockage of all of the ostia. In the isolated sinus es, it was 190 nL/min (antrum) and 68 nL/min (frontal). After 5 minutes sta gnation; NO concentration [NO] rose in the occluded sinuses to 24,700 nL/L in the antrum and 22,300 nL/L in the frontal sinus. In the nose, it increas ed to 29,000 nL/L. When the period of stagnation was prolonged in the front al sinus, the [NO] reached a plateau. NO output and accumulation were not a ltered in the nose or either sinus by opening their ostia. In the antrum an d frontal sinus, lidocaine reduced NO output and the rate of NO accumulatio n, but not in the nose. Conclusions: In this volunteer, 88% of nasal NO was derived from the nose i tself. Nitric oxide exchange between the frontal sinus, antrum, and nose wa s negligible. In the absence of air flow, [NO] rose to a plateau in the nos e and frontal sinus. Lidocaine inhibited NO output in the sinuses but not t he nose.