Dostal D E, Rothblum K N, Chernin M I, Cooper G R, Baker K M
Weis Center for Research, Geisinger Clinic, Danville 17822.
Am J Physiol. 1992 Oct;263(4 Pt 1):C838-50. doi: 10.1152/ajpcell.1992.263.4.C838.
There is increasing evidence that the renin-angiotensin system (RAS) modulates cardiovascular function through both blood-borne and tissue-derived components. The existence of a local RAS has been proposed in the heart based on biochemical and molecular biological studies that identify angiotensinogen and renin. We conducted the present study to determine the chamber localization of angiotensinogen and renin mRNA in neonatal rat heart and whether these components could be identified in cultured cardiomyocytes and fibroblasts obtained from neonatal rat heart. Experiments using polymerase chain reaction (PCR) indicated that whole hearts obtained from neonatal rats contained both angiotensinogen and renin mRNA. With the use of radiolabeled cDNA probes and in situ hybridization, angiotensinogen and renin transcripts were localized both in the atria and ventricles of neonatal rat hearts. Relative signal strengths for angiotensinogen were highest in the left and right ventricles. In contrast, renin signal strength was overall much lower and preferentially localized in the left ventricle. To investigate the cellular source of angiotensinogen and renin, cultured neonatal heart cardiomyocytes and ventricular fibroblasts were screened for angiotensinogen and renin messenger RNA and protein using PCR and indirect immunofluorescent staining, respectively. These experiments demonstrated that both cell types produce transcripts and the respective translation products for angiotensinogen and renin. These data suggest that the site of angiotensin II synthesis can occur at the level of the individual cardiomyocyte and fibroblast, where it may serve to directly and/or indirectly regulate cardiac rate, force, growth, and development in the neonate.
越来越多的证据表明，肾素-血管紧张素系统（RAS）通过血液传播和组织衍生成分来调节心血管功能。基于鉴定血管紧张素原和肾素的生化及分子生物学研究，有人提出心脏中存在局部RAS。我们开展本研究以确定血管紧张素原和肾素mRNA在新生大鼠心脏中的腔室定位，以及这些成分是否能在从新生大鼠心脏获取的培养心肌细胞和成纤维细胞中被鉴定出来。使用聚合酶链反应（PCR）的实验表明，从新生大鼠获取的完整心脏含有血管紧张素原和肾素mRNA。通过使用放射性标记的cDNA探针和原位杂交，血管紧张素原和肾素转录本在新生大鼠心脏的心房和心室中均有定位。血管紧张素原的相对信号强度在左心室和右心室中最高。相比之下，肾素的信号强度总体上要低得多，且优先定位于左心室。为了研究血管紧张素原和肾素的细胞来源，分别使用PCR和间接免疫荧光染色对培养的新生心脏心肌细胞和心室成纤维细胞进行血管紧张素原和肾素信使RNA及蛋白筛查。这些实验表明，这两种细胞类型都能产生血管紧张素原和肾素的转录本及各自的翻译产物。这些数据表明，血管紧张素II的合成位点可能在单个心肌细胞和成纤维细胞水平发生，在那里它可能直接和/或间接调节新生儿的心率、心肌力、生长和发育。
