Katwa L C, Ratajska A, Cleutjens J P, Sun Y, Zhou G, Lee S J, Weber K T
Department of Internal Medicine, University of Missouri Health Sciences Center, Columbia.
Cardiovasc Res. 1995 Jan;29(1):57-64.
The function of angiotensin converting enzyme (ACE) at cell sites of high collagen turnover, such as heart valves, is uncertain. The aim of this study was to assess ACE and kininase-II-like activities and collagen turnover in cultured valvular interstitial cells of the adult rat heart.
The valvular interstitial cell phenotype was determined by immunolabelling (rhodamine phalloidin, desmin, and Griffonia simplicifolia lectin), and the presence of ACE mRNA and protein was confirmed by reverse transcriptase-polymerase chain reaction analysis, ACE monoclonal antibody and in vitro autoradiography, respectively. ACE and kininase-II-like activities in valvular interstitial cells were analysed by high performance liquid chromatography. Angiotensin II (AT1) and bradykinin receptors in valvular interstitial cell membranes were examined by western immunoblotting and binding assay. Type I collagen and collagenase in valvular interstitial cell culture media were determined by ELISA and zymography, respectively. Type I collagen mRNA expression in cultured valvular interstitial cells was determined by northern blot analysis and in situ hybridisation.
In intact valvular interstitial cells or their cell membrane we found: (1) actin microfilaments, but not desmin or lectin labelling; (2) ACE mRNA expression and binding activity; (3) conversion of angiotensin I to angiotensin II, which was completely inhibited by 50 microM lisinopril, while kinase-II-like activity exceeded ACE activity and was not inhibited by lisinopril; (4) AT1 and bradykinin receptors in valvular interstitial cell membrane preparations; (5) type I collagen mRNA expression and collagenase activity; and (6) angiotensin II induced increase in type I collagen synthesis and mRNA expression.
Cultured valvular interstitial cells represent a nonendothelial, non-smooth-muscle cell type that expresses mRNA for ACE and type I collagen. ACE and kininase-II-like activities in valvular interstitial cells may be involved in the regulation of peptides that influence collagen turnover. Angiotensin II stimulates type I collagen synthesis and mRNA expression in these cells.
血管紧张素转换酶（ACE）在高胶原周转率的细胞部位（如心脏瓣膜）的功能尚不确定。本研究的目的是评估成年大鼠心脏培养的瓣膜间质细胞中的ACE和激肽酶-II样活性以及胶原周转率。
通过免疫标记（罗丹明鬼笔环肽、结蛋白和西非单叶豆凝集素）确定瓣膜间质细胞表型，分别通过逆转录-聚合酶链反应分析、ACE单克隆抗体和体外放射自显影证实ACE mRNA和蛋白的存在。通过高效液相色谱分析瓣膜间质细胞中的ACE和激肽酶-II样活性。通过western免疫印迹和结合试验检测瓣膜间质细胞膜中的血管紧张素II（AT1）和缓激肽受体。分别通过ELISA和酶谱法测定瓣膜间质细胞培养基中的I型胶原和胶原酶。通过Northern印迹分析和原位杂交测定培养的瓣膜间质细胞中I型胶原mRNA的表达。
在完整的瓣膜间质细胞或其细胞膜中，我们发现：（1）肌动蛋白微丝，但无结蛋白或凝集素标记；（2）ACE mRNA表达和结合活性；（3）血管紧张素I转化为血管紧张素II，50μM赖诺普利可完全抑制该转化，而激肽酶-II样活性超过ACE活性且不受赖诺普利抑制；（4）瓣膜间质细胞膜制剂中的AT1和缓激肽受体；（5）I型胶原mRNA表达和胶原酶活性；（6）血管紧张素II诱导I型胶原合成和mRNA表达增加。
培养的瓣膜间质细胞代表一种非内皮、非平滑肌细胞类型，表达ACE和I型胶原的mRNA。瓣膜间质细胞中的ACE和激肽酶-II样活性可能参与影响胶原周转率的肽的调节。血管紧张素II刺激这些细胞中I型胶原的合成和mRNA表达。
