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Mechanisms of sympathetic enhancement and inhibition of parasympathetically induced salivary secretion in anaesthetized dogs
Author(s) -
Lung Mary A.
Publication year - 1994
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1994.tb13087.x
Subject(s) - phentolamine , endocrinology , medicine , atropine , yohimbine , stimulation , phenylephrine , prazosin , propranolol , perfusion , acetylcholine , chemistry , blood pressure , antagonist , receptor
1 The effects of superimposed and continuous sympathetic nerve stimulation on submandibular parasympathetic salivation were investigated in anaesthetized dogs. 2 Superimposed sympathetic nerve stimulation (1–2 min) initially enhanced and later inhibited salivary secretion induced by parasympathetic nerve stimulation (2–8 Hz) in glands with uncontrolled blood supply or constant‐flow vascular perfusion. Propranolol (0.05 mg kg −1 , i.a.) did not affect the diphasic sympathetic action whereas phentolamine (0.1 mg kg −1 , i.a.) abolished it. Prazosin (0.025 mg kg −1 , i.a.) greatly lessened the initial enhancement while yohimbine (0.025 mg kg −1 , i.a.) alleviated the late inhibition. 3 Salivary secretion, induced by parasympathetic nerve stimulation (4 Hz) or acetylcholine infusion (10 μg kg −1 min −1 , i.a.), was abolished by atropine (0.05 mg kg −1 , i.a.), increased by phenylephrine infusion (0.25 μg kg −1 min −1 , i.a.) and depressed by clonidine infusion (0.75 μg kg −1 min −1 , i.a.). Hexamethionium (12.5 mg kg −1 , i.a.) abolished the nerve‐induced secretion but had no effect on the acetylcholine‐induced secretion. 4 Continuous background sympathetic nerve stimulation decreased parasympathetic nerve‐induced salivary secretion in glands with uncontrolled blood supply or constant‐flow vascular perfusion. 5 These results show that parasympathetic salivation can be modified by the sympathetic system at the postsynaptic level;