Ultracytochemical localization of the NADPH-d activity in the human nasal respiratory mucosa in vasomotor rhinitis

Objectives: Description of the ultrastructural localization of nitric oxide synthase in the blood vessels of the nasal respiratory mucosa in patients with vasomotor rhinitis, Study Design: This research was conducted on seven patients-men and women, ages 20 to 45 years-suffering from vasomotor rhini tis and who had undergone surgical therapy for reduction of the inferior tu rbinates. Methods: To study the ultrastructural localization of nitric oxid e synthase, NADPH-diaphorase cytochemistry was employed, Samples of the nas al mucosa were obtained from inferior turbinates, Results: The endothelial cells of the arterioles, capillaries, venules and cavernous sinuses reveale d a distribution of the enzymatic activity similar to that found in unaffec ted subjects. A strong enzymatic activity was recognized in the smooth musc le cells of the cavernous sinuses, The smooth muscle cells of arterioles an d venules were generally found to be negative to enzymatic reaction. Conclu sions: This study suggests that the vascular disorders of the vasomotor rhi nitis depend, at least in part, from nitric oxide synthase induction in the smooth muscle cells of the cavernous sinuses.