[Show abstract][Hide abstract] ABSTRACT: Enalaprilat (Ena.), an angiotensin II (Ang II) converting enzyme inhibitor (ACEI), can produce some therapeutic effects on hypertension, ventricular hypertrophy and myocardial remodeling in clinic, but its precise mechanism, especially its signaling pathways remain elusive. In this study, cardiac fibroblasts (CFb) was isolated by the trypsin digestion method; a BrdU proliferation assay was adopted to determine cell proliferation; an immunofluorescence assay was used to measure intracellular reactive oxygen species (ROS); immunocytochemistry staining and Western blotting assay were used to detect phosphorylated p38 mitogen activated protein kinase (p-p38MAPK) and transforming growth factor-β(1) (TGF-β(1)) protein expression, respectively. The results showed that Ang II (10(-7) M) stimulated the cardiac fibroblast proliferation which was inhibited by NAC (an antioxidant), SB203580 (a p38MAPK inhibitor) or enalaprilat; Ang II caused an burst of intracellular ROS level within thirty minutes, an increase in p-p38MAPK (3.6-fold of that in the control group), as well as an elevation of TGF-β(1) meantime; NAC, an antioxidant, and enalaprilat treatment attenuated cardiac fibroblast proliferation induced by Ang II and decreased ROS and p-p38MAPK protein levels in rat cardiac fibroblast; SB203580 lowered TGF-β(1) protein expression in rats' CFb in a dose-dependent manner. It could be concluded that enalaprilat can inhibit the cardiac fibroblast proliferation induced by Ang II via blocking ROS/P38MAPK/TGF-β(1) signaling pathways and the study provides a theoretical proof for the application of ACEIs in treating myocardial fibrosis and discovering the primary mechanism through which ACEIs inhibit CFb proliferation.
[Show abstract][Hide abstract] ABSTRACT: The objectives of this study were to investigate the effects of the angiotensin I-converting enzyme inhibitor enalaprilat (Ena) on the proliferation, hydroxyproline content, and transforming growth factor β1 (TGF-β1) protein expression of neonatal cardiac fibroblasts and to probe its anti-cardiac fibrosis mechanism. Cardiac fibroblast (CFb) was isolated using the trypsin digestion method. Methyl thiazolyl tetrazolium (MTT) colorimetric assay was performed to evaluate cell proliferation, a hydroxyproline method of determination was used to measure collagen content, and reverse transcription-polymerase chain reaction and flow cytometry were used to detect mRNA TGF-β1 and protein levels, respectively, with Ena. Ena decreased dramatically the MTT value, the hydroxyproline content, and inhibited TGF-β1 transcription and protein expression in neonatal rat CFb. The antiproliferative effects of Ena on CFb may be attributed to the inhibition of TGF-β1 transcription and protein expression in cardiac fibroblasts and the antagonistic action of angiotensin II (Ang II).