DISTRIBUTION OF NITRIC-OXIDE SYNTHASE CONTAINING ELEMENTS IN THE FELINE SUBMANDIBULAR-GLAND

Combined nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH -d) histochemistry and nitric oxide synthase (NOS) immunocytochemistry were used to study the distribution of nitric oxide synthesizing elem ents in the cat submandibular gland. A large number of thin varicose f ibres, with intense staining for both markers, were seen around or in close contact with the acini. Some of the stained nerve fibres were as sociated with intra- and interlobular salivary ducts and blood vessels . All neurones in the submandibular ganglia showed intense staining fo r both NADPH-d and NOS. The epithelial layer of the salivary ductal br anches and the endothelial lining of blood vessels were NOS immunonega tive but NADPH-d positive. Our results suggest that NO might act as a neurotransmitter in the regulation of blood flow and secretion in the submandibular salivary gland.