Sawa H, Kawaguchi H, Mochizuki N, Endo Y, Kudo T, Tokuchi F, Fijioka Y, Nagashima K, Kitabatake A
Department of Cardiovascular Medicine and Pathology, Hokkaido University School of Medicine, Sapporo, Japan.
Mol Cell Biochem. 1994 Mar 16;132(1):15-23. doi: 10.1007/BF00925670.
Extrahepatic synthesis and localization of angiotensinogen (ATN) have been described in animals, thus establishing the tissue renin-angiotensin (RA) system. However, there had been no reports of tissue RA systems in human organs, including the heart. In earlier, we have reported the possibility of ATN synthesis in the human heart using ribonuclease protection assay system. ATN mRNA was detected not only in the liver, but also in both the atrial and ventricular heart tissues, suggesting that ATN is synthesized in the human heart. In this report, we looked for the distribution of ATN in diseased human heart. Northern blot hybridization of cDNA with total RNA extracted from human liver, brain, kidney, atrial and ventricular tissues revealed that ATN mRNA exists in cardiac ventricule. Immunohistochemical studies using a specific antibody to ATN revealed a stronger reaction in the endocardial layer of the human left ventricle, than in the epicardial layer, and intense immunoreactivity in the conduction system and right atrium. This distribution pattern was similar to that of human atrial natriuretic peptide (hANP), which functions a smooth muscle relaxant. Double immunostaining of ATN and hANP demonstrated that all myocytes in the right atrium had immunopositive reactions to ATN, hANP or both of ATN and hANP. Double immunoelectron staining enabled us to show more detailed localization of ATN and hANP; hANP only existed in the specific granules and ATN existed in the myofibril, but not in the granule. Furthermore, our experiments provide evidence of ATN in healthy human hearts and also reveal a widespread immunopositive reaction for ATN in the left ventricle of diseased hearts.
动物体内已发现血管紧张素原（ATN）的肝外合成及定位，由此确立了组织肾素 - 血管紧张素（RA）系统。然而，此前尚无关于包括心脏在内的人体器官中组织RA系统的报道。早期，我们曾利用核糖核酸酶保护分析系统报道过人体心脏中存在合成ATN的可能性。不仅在肝脏中检测到了ATN mRNA，在心房和心室组织中也检测到了，这表明人体心脏能够合成ATN。在本报告中，我们研究了患病人体心脏中ATN的分布情况。用从人肝脏、脑、肾、心房和心室组织中提取的总RNA与cDNA进行Northern印迹杂交，结果显示ATN mRNA存在于心室中。使用针对ATN的特异性抗体进行免疫组织化学研究发现，人左心室心内膜层的反应比心外膜层更强，且在传导系统和右心房中有强烈的免疫反应性。这种分布模式与具有平滑肌舒张功能的人心房钠尿肽（hANP）相似。ATN和hANP的双重免疫染色表明，右心房中的所有心肌细胞对ATN、hANP或ATN与hANP两者均有免疫阳性反应。双重免疫电子染色使我们能够更详细地显示ATN和hANP的定位；hANP仅存在于特定颗粒中，而ATN存在于肌原纤维中，而非颗粒中。此外，我们的实验提供了健康人体心脏中存在ATN的证据，同时也揭示了患病心脏左心室中ATN广泛的免疫阳性反应。
