Decker R S, Poole A R, Griffin E E, Dingle J T, Wildenthal K
J Clin Invest. 1977 May;59(5):911-21. doi: 10.1172/JCI108713.
To determine the influence of cardiac ischemia on the activity and subcellular localization of lysosomal cathepsin D, anesthetized rabbits were subjected to ligation of the circumflex coronary artery. Total enzyme activity remained unchanged throughout the 2-h ischemic period, but the subcellular distribution of cathepsin D, as analyzed by biochemical and immunohistochemical techniques, was altered dramatically. A marked increase in nonsedimentable (i.e., 40,000-g supernate) activity developed by 30-45 min and increased further by 2 h. Simultaneously, the immunofluorescent localization of cathepsin D was also changed significantly. Within 30-60 min after occlusion, the fine, particulate staining observed in control myocytes was replaced by bright fluorescent patches composed of large granules. Many of these structures displayed prominent halos of diffuse fluorescent staining in the neighboring myocytic cytoplasm, apparently outside lysosomes per se. After 2 h, when nonsedimentable activity was maximally elevated, most of the fluorescent particles had disappeared completely. During this same interim there was no detectable change in the distribution of lysosomal cathepsin D within interstitial cells. These results are consistent with the hypothesis that an early feature of cardiac ischemia is the release of cathepsin D from myocytic lysosomes into the cytosol of damaged cells.
为了确定心肌缺血对溶酶体组织蛋白酶D活性和亚细胞定位的影响，对麻醉的家兔进行了冠状动脉回旋支结扎。在整个2小时的缺血期内，总酶活性保持不变，但通过生化和免疫组化技术分析，组织蛋白酶D的亚细胞分布发生了显著变化。在30 - 45分钟时，不可沉淀（即40,000g超速离心上清液）活性显著增加，并在2小时时进一步升高。同时，组织蛋白酶D的免疫荧光定位也发生了显著变化。在闭塞后30 - 60分钟内，对照心肌细胞中观察到的细微颗粒状染色被由大颗粒组成的明亮荧光斑块所取代。许多这些结构在相邻心肌细胞质中显示出明显的弥漫性荧光染色晕圈，显然位于溶酶体本身之外。2小时后，当不可沉淀活性最大程度升高时，大多数荧光颗粒完全消失。在同一时期，间质细胞内溶酶体组织蛋白酶D的分布没有可检测到的变化。这些结果与以下假设一致，即心肌缺血的早期特征是组织蛋白酶D从心肌细胞溶酶体释放到受损细胞的细胞质中。
