Watanabe T, Watanabe M, Ishii Y, Matsuba H, Kimura S, Fujita T, Kominami E, Katunuma N, Uchiyama Y
Department of Anatomy, University of Tsukuba, Ibaraki-Ken, Japan.
J Histochem Cytochem. 1989 Mar;37(3):347-51. doi: 10.1177/37.3.2521876.
To examine localization of cathepsin B, a representative lysosomal cysteine protease, in atrial myoendocrine cells of the rat heart, immunohistochemistry at the light and electron microscopic level was applied to the atrial tissue, using a monospecific antibody for rat liver cathepsin B. In serial semi-thin sections, immunoreactivity for cathepsin B and atrial natriuretic peptides (ANP) was detected in the para-nuclear region of atrial myoendocrine cells. Several large granules and many fine granules in the region of the cells were positively stained by the cathepsin B antibody. Gold particles indicating cathepsin B antigenicity labeled secretory granules in the cells, which were also labeled by those indicating ANP, using thin sections of the Lowicryl K4M-embedded material. Moreover, some granules labeled densely by immunogold particles for cathepsin B seemed to be lysosomes. By double immunostaining using thin sections of the Epon-embedded material, gold particles indicating cathepsin B and ANP antigenicities were co-localized in secretory granules of the cells. By enzyme assay, activity of cathepsin B was three times higher in atrial tissue than ventricular tissue. The results suggest that co-localization of cathepsin B and ANP in secretory granules is compatible with the possibility that cathepsin B participates in the maturation process of ANP.
为了研究组织蛋白酶B（一种典型的溶酶体半胱氨酸蛋白酶）在大鼠心脏心房肌内分泌细胞中的定位，利用针对大鼠肝脏组织蛋白酶B的单特异性抗体，对心房组织进行了光镜和电镜水平的免疫组织化学研究。在连续半薄切片中，在心房肌内分泌细胞的核周区域检测到了组织蛋白酶B和心房利钠肽（ANP）的免疫反应性。细胞区域内的几个大颗粒和许多细颗粒被组织蛋白酶B抗体阳性染色。使用Lowicryl K4M包埋材料的薄切片，显示组织蛋白酶B抗原性的金颗粒标记了细胞内的分泌颗粒，这些颗粒也被显示ANP的金颗粒标记。此外，一些被组织蛋白酶B免疫金颗粒密集标记的颗粒似乎是溶酶体。通过使用Epon包埋材料的薄切片进行双重免疫染色，显示组织蛋白酶B和ANP抗原性的金颗粒共定位于细胞的分泌颗粒中。通过酶活性测定，心房组织中组织蛋白酶B的活性比心室组织高3倍。结果表明，组织蛋白酶B和ANP在分泌颗粒中共定位，这与组织蛋白酶B参与ANP成熟过程的可能性相符。
