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KMID : 0376219870240020165
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Chonnam Medical Journal
1987 Volume.24 No. 2 p.165 ~ p.173
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Dual Effect of the Cervical Sympathetic Stimulation Depending on the Reflex submaxillary Secretion Rate Evoked by Stimulation of the Afferent Lingual Nerve in Cats
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Abstract
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The cervical sympathetic nerve distributed to the submaxillary gland has been assumed to carry specific secretory fibers as well as vasoconstrictor fibers, although there is a possibility that a transient flow of small amount of saliva evoked by the cervical sympathetic stimulation may be due to exci￢tation of motor fibers innervating glanduar contractile elements which can expel saliva already present in the ducts, or that it may be caused by adre￢nergic neurotransmitter diffusing from the vasoconstrictor nerve terminals to the secretory cells. Recently, the existence of specific secretory fibers in the cervical sympathetic nerve and its physiologic function are still obscure. Referring some literatures, the effect of the cervical sympathetic nerve on the submaxillary secretion seems to differ depending on salivary secretion rate. The present study was attempted to know the effects of the cervical sympa￢thetic stimulation depending on the reflex submaxillary secretion rate evoked by stimulation of the central stump of the lingual nerve in ketamine anesthe￢tized cats.
Maximal secretion rate on the unconditioned reflex submaxillary secretion was elicited by stimulation of the afferent lingual nerve with the relative high frequency(20Hz). When the submaxillary gland is undergoing maximal secretion by stimulation of the afferent lingual nerve, superimposed stimula￢tion of the cervical sympathetics always elicited decrease both in salivary and blood flows. However, the decreased blood flow always preceded the decrease in salivary flow on the stimulation of the cervical sympathetics and the decreased blood flow recovered prior to the salivary flow upon cessation of the sympathetic stimulation. When the gland is producing submaximal secre￢tion by stimulation of the afferent lingual nerve with lower frequency(5Hz), superimposed stimulation of the cervical sympathetics produced transiently increase in secretion which is followed by a compensatory decrease, so that total amount of saliva collected from the gland during the whole period of the lingual nerve stimulation was not changed by the stimulation of the cervi￢cal sympathetics. Intraluminal pressure of the submaxillary duct was increa￢sed by the stimulation of the cervical sympathetics or the admininistration of noradrenaline.
These results indicate that excitation of the cervical sympathetics produces dual effect, the acceleratory and the inhibitory, depending on the submaxillary secretion rate. The acceleratory effect, a transient increase, on the submaxi￢mal secretion rate seems to be caused by contraction of the glandular contrac￢tile elements which are more excitable in low intraluminal pressure in the ducts, and the inhibitory effect on the maximal secretion rate is caused by decreasing the blood flow to the gland via the excitation of the sympathetic vasoconstrictor fibers. The existence of specific secretory sympathetic fibers for the submaxillary gland should be reappraised.
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KEYWORD
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