抄録
The present experiments were performed with dog's submaxillary gland, (a) for the identification of efferent nervous pathways which mediate the impulse from brain to the submaxillary gland in reflecting the blood tonicity upon salivary salt concentration, and (b) for the elucidation of the mechanism involved therein. The results are as follows:
(1) It was confirmed that the reflection of changes in tonicity of blood upon salivary salt concentrations are effected not only by the direct effect of blood circulating in the gland, but also by the nervous control from the osmoreceptor in the brain. The present experiments revealed that this impulse from the brain is transmitted through three nerves, i. e., chorda tympani, vagal, and hypoglossal nerve.
(2) The function of duct cells being impaired by HgCl2 injection, the intraglandular activities involved in the mechanism of salt secretion was analysed. The saliva collected from the gland impaired by HgCl2, presented higher ionic concentration than that from the control gland and the concentration was maintained constant irrespective of variation of rate of salivary flow. It is inferred that the saliva thus collected from the gland treated with HgCl2 is the precursor saliva secreted from the acinus and the experimental verification by the previous authors that the dependence of the ionic concentration on the rate of salivary flow is effected by the activity of the duct was confirmed. It was verified by the stop-flow analysis that the duct epithelium displays the reabsorption of Na+and Cl-and the secretion of K+in precursor saliva.
(3) It was clarified by experiments with the HgCl2 gland that the nervous impulse mentioned in (1) affects the reabsorption of Na+and Cl-from the precursor saliva running through the duct.
(4) The factors involved in the mechanism reflecting the change in blood salt concentration upon salivary composition were discussed and their quantitative analysis was attempted.
