ABSORPTION OF I125-LABELED HOMOLOGOUS ALBUMIN BY RAT KIDNEY PROXIMAL TUBULE CELLS - A STUDY OF MICROPERFUSED SINGLE PROXIMAL TUBULES BY ELECTRON MICROSCOPIC AUTORADIOGRAPHY AND HISTOCHEMISTRY
ABSORPTION OF I125-LABELED HOMOLOGOUS ALBUMIN BY RAT KIDNEY PROXIMAL TUBULE CELLS - A STUDY OF MICROPERFUSED SINGLE PROXIMAL TUBULES BY ELECTRON MICROSCOPIC AUTORADIOGRAPHY AND HISTOCHEMISTRY
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DOI：
10.1016/s0022-5320(66)80108-9
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发表时间：
1966-01-01
期刊：
影响因子：
--
通讯作者：
MAUNSBACH, AB
中科院分区：
文献类型：
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作者：
MAUNSBACH, AB
通过微量移液管将少量 I125 标记的大鼠白蛋白注射到大鼠肾的单个近端小管中。在不同的时间间隔后，用戊二醛微灌注固定注射的小管，并通过电子显微镜放射自显影分析组织。在标记蛋白的吸收过程中，近曲小管细胞没有观察到超微结构的改变。 I125-白蛋白灌注开始后 6 至 10 分钟，大部分吸收的蛋白质位于近端小管细胞的大顶端液泡中，但一些标记也与小顶端液泡相关。观察结果表明，标记的白蛋白通过小顶端液泡转移到大顶端液泡，这很可能代表被夹断的顶端细胞膜内陷。 30分钟后。大部分标记存在于细胞质体中，细胞质体受到厚度约为90埃的三层膜的限制，并且具有电子致密内容，并且位于细胞的中部或顶端区域。 60分钟后。标记仅限于位于细胞所有区域的相似细胞质体。结合电子显微镜放射自显影和组织化学证明标记的细胞质体呈酸性磷酸酶阳性。后一观察表明，IL25-白蛋白所在的细胞质体是溶酶体。这表明至少一些吸收的白蛋白在这些溶酶体中被降解。没有放射自显影或形态学证据表明标记的白蛋白通过细胞之间穿过近端小管壁，或者含有吸收的白蛋白的液泡或细胞质体排空到小管周围空间。
Small amounts of I125-labeled rat albumin were injected through micro-pipettes into single proximal tubules of the rat kidney. After different time-intervals the injected tubules were microperfusion-fixed with glutaraldehyde and the tissue analyzed by electron microscopic autoradiography. No ultrastructural alterations were observed in the proximal tubule cells during the absorption of the labeled protein. Six to 10 minutes after start of I125-albumin perfusion most of the absorbed protein was located in the large apical vacuoles in the proximal tubule cells but some label was also associated with small apical vacuoles. The observations suggest that the labeled albumin was transferred to the large apical vacuoles via small apical vacuoles which most likely represented pinched-off apical cell membrane lnvaginations. After 30 min. most of the label was present in cytoplasmic bodies, which were limited by a triple-layered membrane about 90 A in thickness and had an electron-dense content, and which were located in the middle or apical regions of the cells. After 60 min. the label was confined to similar cytoplasmic bodies located in all regions of the cells. Combined electron microscopic autoradiography and histochemistry demonstrated that the labeled cytoplasmic bodies were acid phosphatase positive. The latter observation indicates that the cytoplasmic bodies, in which the Il25-albumin was located, were lysosomes. It is suggested that at least some of the absorbed albumin was degraded in these lysosomes. There was no autoradlographic or morphologic evidence that the labeled albumin crossed the wall of the proximal tubule by passing between the cells or that vacuoles or cytoplasmic bodies containing absorbed albumin emptied into the peritubular space.