Regulation of hemodynamics in major salivary glands by parasympathetic vasodilation

Abstract Background Since salivary fluid is created from blood plasma, hemodynamics in the salivary glands play an important role in the production of saliva. Trigeminal sensory input induces both salivary secretion and reflex parasympathetic vasodilation in salivary glands. This glandular vasodilation is thought to be important for the regulation of glandular hemodynamics due to the rapidity with which blood flow is increased. This review article summarizes recent research on the involvement of parasympathetic vasodilation in regulating hemodynamics in the salivary gland. Highlight Electrical stimulation of the lingual nerve, a branch of the trigeminal nerve, elicits parasympathetic vasodilation in the salivary glands. Parasympathetic vasodilation is mainly evoked by cholinergic fibers in the submandibular and parotid glands and by cholinergic and vasoactive intestinal peptide (VIP)-ergic fibers in the sublingual gland. The vasodilator mechanism changes from cholinergic to VIP-ergic when muscarinic receptors are deactivated. Conclusion Glandular hemodynamics in the submandibular, parotid, and sublingual glands are regulated by different parasympathetic vasodilator mechanisms, which may functionally contribute to the differences in secretion among the major salivary glands.