Parasympathetic-mediated reflex salivation and vasodilatation in the cat submandibular gland

The aim of the present study was to compare and characterize the secretory and vasodilator effects induced by chorda lingual nerve (CLN) stimulation (i.e., direct parasympathetic stimulation) and reflex parasympathetic stimulation in the submandibular gland (SMG) of sympathectomized cats. The increase in blood flow and salivary secretion in response to electrical stimulation of the central cut ends of the vagus and inferior alveolar nerves, as well as to stimulation of the CLN at a site approximately 5 mm distal to the intersection of the CLN and the SMG duct (site D) was completely abolished by section of the chorda tympani nerve (CTN). Neither response to CLN stimulation at a site nearly 5 mm proximal to the intersection of the CLN and the SMG duct (site C) was affected by CTN section. Section of the CLN at a site approximately 5 mm distal to the intersection of the CTN and the CLN abolished the submandibular salivary and vasodilator responses elicited by CLN stimulation at site D but had no effect on the two responses evoked by CLN stimulation at site C. The blood flow increases evoked by electrical stimulation of the CLN at site D were greatly reduced by prior treatment with the autonomic ganglion blocker hexamethonium, but the vasodilator responses evoked from site C were reduced much less. These data suggest that the secretory and vasodilator responses elicited by CLN stimulation at site D and those by vagus and inferior alveolar nerve stimulation are mediated largely via a parasympathetic reflex mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)