Coupling mechanisms between fluid secretion and exocytosis

探讨体液分泌与胞外分泌的耦合机制。a .分泌时间过程：腮腺和下颌下腺分别作为浆液和浆液分泌模型。淀粉酶和粘蛋白的分泌时间过程相似，单次毒蕈碱刺激引起蛋白质分泌初期爆发，随后持续低水平分泌，β-肾上腺素能刺激超载导致蛋白质分泌增加，随后高水平分泌。液体分泌主要由毒蕈碱刺激引起，β-肾上腺素能刺激引起。在弱毒蕈碱刺激时，β-肾上腺素能刺激可增强体液分泌。这表明环AMP对转运蛋白的上调可能受到代谢能量供应和过量的胞质Ca^<2+>B的限制。形态学观察：电镜观察灌注全腮腺随分泌时间的变化。单次乙醇刺激引起细胞间小管（IC）的初始瞬时扩大。甲氨基酚和异丙肾上腺素的联合刺激可引起icd的强烈胞外分泌，两种刺激a)减少微绒毛的数量，b)增加内质网。提示激活了Ca^<2+>代谢，c)线粒体电子密度增加，与耗氧量增加有关。共聚焦激光显微镜观察发现，腮腺的分泌途径受分泌刺激控制，分泌初期以胞外液分泌为主。c .胞外分泌的分子机制：腮腺分泌颗粒膜上鉴定出VAMP-2，发光膜上鉴定出syntaxin4和SNAP23。而syntaxin 1A则定位于舌腺的腺泡细胞。这表明黏液分泌和浆液分泌在胞外机制上存在一定差异。d .分泌分子动力学：通过毒菌碱刺激分泌过程中不同大小的标记葡聚糖的唾液/灌注比来估计细胞旁途径的分子过滤器的大小，如5A。对绵羊颊腺分泌液的阴离子依赖性进行了精确的研究。因此，该项目揭示了上述新发现，表明细胞内信号的组合可以在各个方面耦合液体分泌和胞外分泌。少

To study a coupling mechanism between fluid secretion and exocytosis. the major salivary glands were examined physiologically and morphologically as a model to produce a macroscopic secretion with various concentration of protein.A.Secretory time course : The parotid and submandibular glands were used as models of serous and seromucous secretion, respectively. The secretory time course of amylase and mucin was similar, a single muscarinic stimulation induced an initial burst of protein secretion followed by low sustained level of secretion, Overloading of β-adrenergic stimulation increased the protein secretion followed by high secretion level. Fluid secretion was induced by mainly muscarinic stimulation, but a minimal by β-adrenergic stimulation. During weak muscarinic stimulation, the fluid secretion was potentiated by β-adrenergic stimulation. This suggests that the upregulation of transporters by cyclic AMP could be limited by metabolic energy supply and excess cytosolic Ca^<2+>B.M … More orphology : Morphological change of the perfused whole parotid gland was examined by electron microscope along secretory time course. A single carbachol stimulation caused an initial transient enlargement of intercellular canalliculi (IC). Combined stimulation of carbachol and isoproterenol induced a vigorous exocytosis on IC.Either stimulation a) reduced the number of microvilli, b) enlarge the rER.suggesting activation of Ca^<2+> metabolism, and c) increased electron density of mitochondria, related to the increase of oxygen consumption. Confocal laser microscope revealed that the paracellular route of secretion is controlled by secretory stimulation, and that the transcellular fluid secretion is dominant at initial secretory phase.C.Molecular machinary for exocytosis : In the parotid gland VAMP-2 was identified on the secretory granule membrane, syntaxin4 and SNAP23 were located on the luminar membrane. Whereas, syntaxin 1A was localized at acinar cells of the lingual glands. This suggests that there is some differnce in exocytotic mechanism between mucinous and serous secretion.D.Dynamics of secretory molecules : The size of molecular filter across the paracellular route was estimated from the saliva/perfusate ration of various size of labelled dextran during secretion by muscarinic stimulation, as 5A.Anionic dependency of fluid secretion was examined precisely in the buccal gland of sheep.Thus the project revealed above new findings to show that combination of intracellular signals enables coupling between fluid secretion and exocytosis at various aspects. Less