Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden.
Department of Biomedicine, Faculty of Medicine, University of Bergen, Bergen, Norway.
Eur J Cell Biol. 2020 Nov;99(8):151127. doi: 10.1016/j.ejcb.2020.151127. Epub 2020 Nov 4.
Blood levels of cardiac troponins (cTn) and myoglobin are analysed when myocardial infarction (MI) is suspected. Here we describe a novel clearance mechanism for muscle proteins by muscle cells. The complete plasma clearance profile of cTn and myoglobin was followed in rats after intravenous or intermuscular injections and analysed by PET and fluorescence microscopy of muscle biopsies and muscle cells. Compared with intravenous injections, only 5 % of cTnT, 0.6 % of cTnI and 8 % of myoglobin were recovered in the circulation following intramuscular injection. In contrast, 47 % of the renal filtration marker FITC-sinistrin and 81 % of cTn fragments from MI-patients were recovered after intramuscular injection. In addition, PET and biopsy analysis revealed that cTn was taken up by the quadriceps muscle and both cTn and myoglobin were endocytosed by cultured muscle cells. This local clearance mechanism could possibly be the dominant clearance mechanism for cTn, myoglobin and other muscle damage biomarkers released by muscle cells.
当怀疑发生心肌梗死（MI）时，会分析血液中心脏肌钙蛋白（cTn）和肌红蛋白的水平。在这里，我们描述了一种肌肉细胞清除肌肉蛋白的新机制。在静脉或肌肉内注射后，通过 PET 和肌肉活检及肌肉细胞的荧光显微镜，对大鼠 cTn 和肌红蛋白的完整血浆清除曲线进行了研究。与静脉注射相比，肌肉内注射后，仅 5%的 cTnT、0.6%的 cTnI 和 8%的肌红蛋白在循环中被回收。相比之下，在肌肉内注射后，47%的肾滤过标志物 FITC-辛糖和 81%的 MI 患者来源的 cTn 片段被回收。此外，PET 和活检分析显示 cTn 被股四头肌摄取，cTn 和肌红蛋白都被培养的肌肉细胞内吞。这种局部清除机制可能是肌肉细胞释放的 cTn、肌红蛋白和其他肌肉损伤生物标志物的主要清除机制。
