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KMID : 0376219850220020205
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Chonnam Medical Journal
1985 Volume.22 No. 2 p.205 ~ p.212
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Effects of the Cervical Sympathetic Stimulation Depending on Submaxillary Secretory Rate Evoked by Stimulation of the Chorda Tympani in Cats
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Abstract
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Since the time of Ludwig and Heidenhain, the cervical sympathetic trunk has been assumed to carry specific secretory fibers for the submaxillary gland. But recently, the inhibitory effect of the cervical sympathetic on the reflex submaxillary secretion was reported, and it was also described that the efferent pathway of the reflex submaxillary secretion is the chorda tympani, not the cervical sympathetic. Furthermore, if both nerves, parasympathetic and sympathetic, are able to affect the secretory response, in the same means, the physiological significance of the double enervation of the glands becomes obscure. These facts are strongly against the assumption that the cervical sympathetic to the glands contains specific secretory fibers.
As the autonomic nerves in the salivary glands are also known to control structures other than secretory cells, there is a possibility that a transient accelerated flow of saliva by the cervical sympathetic stimulation may be due to contractions of myoepithelial cells and smooth muscle fibers contained in the duct wall. On the other hand, the serectory response of the submaxillary gland to stimulation of the cervical sympathetic may differ depending on the secretion rate. The present study was attempted to know whether the effects of cervical sympathetic stimulation are dependent on the serectory rate of the gland evoked by stimulation of the chorda tympani.
In ketamine-anesthetized cats, spontaneous submaxillary secretion was not. observed. Stimulation of the chorda tympani elicited copious salivary secretion. When maximal secretion was evoked by stimulation of chorda tympani with high freqency (20Hz), superimposed stimulation of the cervical sympathetics within effective frequencies always elicited decrease in secretion. But when the gland is undergoing submaximal secretion by stimulation of the chorda tympani with lower frequency (5Hz), the secretory rate slightly increased by superimposed stimulation of the sympathetics. However the increased flow is followed by a compensatory decrease, so that total amount of saliva collected from the gland during the whole period of the chorda stimulation was not affected by superimposed sympathetic stimulation.
These results indicate that stimulation of the cervical sympathetic innervated to the submaxillary gland produces dual effect, acceleratory and inhibitory, depending on the serectory rate. The acceleratory effect on the submaximal salivary flow seems to be caused by contractions of the contractile elements of the duct, whereas the inhibitory effect on the maximal secretion is produced by decreased blood flow through the gland, as shown in previous studies.
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