Emmelin N, Gjörstrup P, Thesleff P
Q J Exp Physiol Cogn Med Sci. 1977 Jan;62(1):27-40. doi: 10.1113/expphysiol.1977.sp002374.
Duct pressure and salivary flow were recorded in submaxillary glands of anaesthetized dogs, to study whether parasympathetic stimulation caused effects referable to activity in myoepithelial cells. At fairly low frequency of stimulation, e.g. 3 Hz, the pressure curve had two distinct components, with initial steep and a secondary gradual rise. It resembled that obtained on sympathetic stimulation, where the first phase is ascribed to myoepithelial contraction, the second phase to secretion. When parasympathetic stimulation ceased, there was first a steep fall, then a more gradual decline of the pressure. The steep fall was of the same magnitude as the steep rise; both increased with the frequency of stimulation. The size of the initial fall was fairly independent of the pressure level from which it started. Such a steep fall did not occur subsequent to parasympathetic stimulation if the myoepithelial cells were already in a state of strong contraction caused by sympathetic impulses or bradykinin. The phase of steep fall was inferred to be due mainly to relaxation of contracted myoepithelial cells, the following decline to back-flow of fluid into the gland. The salivary flow rate was highest at the beginning of a period of parasympathetic stimulation, particularly if the duct system was well filled and the saliva thin. It was concluded that myoepithelial contraction had initially expelled saliva. A brief period of parasympathetic stimulation while a slow basal secretion at constant rate was going on was found to accelerate this flow, and afterwards there was a transient deceleration of the flow. Acceleration was attributed partly to myoepithelial contraction, mainly to superimposed secretion; retardation to myoepithelial relaxation. The effect appeared independently of the way in which the basal flow was evoked, and the retardation resembled that seen after sympathetic stimulation or bradykinin.
在麻醉犬的颌下腺中记录导管压力和唾液流量，以研究副交感神经刺激是否会引起与肌上皮细胞活动相关的效应。在相当低的刺激频率下，例如3赫兹，压力曲线有两个明显的成分，先是急剧上升，然后是逐渐上升。这与交感神经刺激时获得的曲线相似，其中第一阶段归因于肌上皮收缩，第二阶段归因于分泌。当副交感神经刺激停止时，压力首先急剧下降，然后逐渐下降。急剧下降的幅度与急剧上升的幅度相同；两者都随着刺激频率的增加而增加。初始下降的幅度相当独立于其起始的压力水平。如果肌上皮细胞已经处于由交感神经冲动或缓激肽引起的强烈收缩状态，那么在副交感神经刺激后不会出现这样的急剧下降。推断急剧下降阶段主要是由于收缩的肌上皮细胞的松弛，随后的下降是由于液体回流到腺体。在副交感神经刺激开始时，唾液流速最高，特别是如果导管系统充盈良好且唾液稀薄。得出的结论是，肌上皮收缩最初排出了唾液。发现在持续进行缓慢基础分泌的同时进行短时间的副交感神经刺激会加速这种流动，之后流量会有短暂的减速。加速部分归因于肌上皮收缩，主要归因于叠加的分泌；减速归因于肌上皮松弛。这种效应的出现与引发基础流量的方式无关，并且减速与交感神经刺激或缓激肽后观察到的情况相似。
