Alteration of tight junctional permeability in the rat parotid gland after isoproterenol stimulation.
Alteration of tight junctional permeability in the rat parotid gland after isoproterenol stimulation.
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DOI：
10.1083/jcb.98.5.1865
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发表时间：
1984-05
影响因子：
7.8
通讯作者：
Hand, A R
中科院分区：
文献类型：
--
作者：
Mazariegos, M R;Tice, L W;Hand, A R
在静息和刺激的大鼠腮腺中研究了连接复合物对不同分子量超微结构示踪剂的渗透性以及连接结构的冷冻断裂外观。示踪剂通过主排泄管逆行施用，并允许通过重力（16 mmHg）流入腺体15-60分钟。通过腹膜内注射异丙肾上腺素在一些动物中诱导分泌。在静息腺体中，示踪剂微过氧化物酶、细胞色素 c、肌红蛋白、酪氨酸酶（亚基）和血红蛋白仅限于腺泡和导管的管腔空间。在示踪剂施用前1-4小时刺激的腺体中，在细胞间和间质空间中发现了微过氧化物酶、细胞色素c、肌红蛋白和酪氨酸酶的反应产物，而血红蛋白通常保留在管腔中。相反，辣根过氧化物酶和乳过氧化物酶似乎穿透紧密连接，并且反应产物定位于静息腺体和受刺激腺体的细胞外空间中。在腺泡和导管细胞中经常观察到辣根过氧化物酶和乳过氧化物酶的弥漫性细胞质染色。辣根过氧化物酶在 Sprague-Dawley 和 Wistar-Furth 大鼠中的分布相似，示踪剂溶液中的浓度为 0.1-10 mg/ml。受刺激的腺泡细胞的冷冻断裂复制品显示紧密连接网络的不规则性增加，但没有观察到明显的间隙或不连续性。这些发现表明 (a) 静息大鼠腮腺中的紧密连接对于分子量大于或等于 1,900 的示踪剂是不可渗透的； (b) 用异丙肾上腺素刺激导致交界通透性短暂增加，允许分子量小于或等于 34,500 的示踪剂通过； (c) 连接渗透性不能与连接结构直接相关； (d)大鼠腮腺中辣根过氧化物酶和乳过氧化物酶的行为与其分子量不一致。由于酶活性或这两种示踪剂的结合造成的细胞膜损伤可能是观察到的分布的原因。
The permeability of junctional complexes to ultrastructural tracers of different molecular weight and the freeze-fracture appearance of junctional structure were investigated in the resting and stimulated rat parotid gland. Tracers were administered retrogradely via the main excretory duct, and allowed to flow by gravity (16 mmHg) into the gland for 15-60 min. Secretion was induced in some animals by intraperitoneal injection of isoproterenol. In resting glands, the tracers microperoxidase , cytochrome c, myoglobin, tyrosinase (subunits), and hemoglobin were restricted to the luminal space of the acini and ducts. In glands stimulated 1-4 h before tracer administration, reaction product for microperoxidase , cytochrome c, myoglobin, and tyrosinase was found in the intercellular and interstitial spaces, whereas hemoglobin was usually retained in the lumina. In contrast, horseradish peroxidase and lactoperoxidase appeared to penetrate the tight junctions and reaction product was localized in the extracellular spaces in both resting and stimulated glands. Diffuse cytoplasmic staining for horseradish peroxidase and lactoperoxidase was frequently observed in acinar and duct cells. The distribution of horseradish peroxidase was similar in both Sprague-Dawley and Wistar-Furth rats, and at concentrations of 0.1-10 mg/ml in the tracer solution. Freeze- fracture replicas of stimulated acinar cells revealed an increased irregularity of the tight junction meshwork, but no obvious gaps or discontinuities were observed. These findings indicate that (a) tight junctions in the resting rat parotid gland are impermeable to tracers of molecular weight greater than or equal to 1,900; (b) stimulation with isoproterenol results in a transient increase in junctional permeability allowing passage of tracers of molecular weight less than or equal to 34,500; (c) junctional permeability cannot be directly correlated with junctional structure; and (d) the behavior of horseradish peroxidase and lactoperoxidase in the rat parotid gland is inconsistent with their molecular weights. Cell membrane damage due to the enzymatic activity or binding of these two tracers may account for the observed distribution.