Evidence that nitric oxide or a related substance is a neurovasodilator in the submandibular gland of the cat.

Close-arterial injection of L-NG-nitro arginine methyl ester, a compound that inhibits the synthesis of nitric oxide (NO), caused a dose-dependent reduction in both the parasympathetic and sympathetic (rebound) nerve-induced vasodilatation within the submandibular gland of the cat. At the same time, salivary secretion produced by each nerve was relatively unaffected, and the sympathetic vasoconstriction was enhanced. These results suggest that NO or a related compound may be either a neurotransmitter or neuromodulator contributing to the autonomic nerve-induced vasodilatation in the submandibular gland of the cat.