Estudo bioquímico e imunohistoquímico da enzima conversora de angiotensina e da quimase no fluido pericárdico e no pericárdio parietal bovino

Abstract

The mammalia pericardium consists of a serous membrane and a fibrous sac. The serous covers the outside of the heart (pericardium visceral and lines the inside of the fibrous sac (parietal pericardium). The space among parietal and visceral pericardium contain the pericardial fluid wich serves as lubricant and play many local roles. The composition of this fluid is considered as an ultrafiltrate of plasma enriched in molecules, such as prostaglandins, atrial natriuretic factor, growth factors and angiotensin (Ang II). The classic vision of Ang II as vasoactive molecule that participates of systemic and local hemodynamic regulation has been expanded. This peptide nowadays is considered as a cytokine presents an active role in cardiovascular pathology with pro-fribrotic and pro-inflammatory effects. Studies demonstraded that chymase is an alternative pathway of Ang II synthesis. The aims of this study was to show the presence of ACE and chymase in the bovine pericardial fluid, quantify the mast cells and identify the presence of both enzymes on the bovine parietal pericardium. The results obtained allowed the identification of an ACE isoform in the pericardial fluid weighing about 146 kDa, after immunoreaction on nitrocellulose membrane. In sections of the pericardial membrane, ACE has been identified along the mesothelial layer. It s suggesting this layer can be a source that produce part of the ACE in pericardial fluid. Regarding chymase, an enzyme of the alternative pathway of Ang II , has not been possible to detect the presence of this enzyme in samples of this fluid after immunoreaction on nitrocellulose membrane. Through histochemical reactions, mast cells were identified and quantified in the pericardial membrane. The average density was 43.77 ± 14.73 cells / mm ² per animal. In relation to the integrity of these cells, the density of degranulated, median, mast cells was greater than the density of mast cell granules, and this difference was statistically significant. Finally, the immunodetection of chymase by fluorescence microscopy, allowed for the first time, the identification of chymase positive mast cells in sections of bovine tissues, although small amounts.