Adaptação de um sistema de ensaio biológico para detecção de fatores relaxantes endoteliais derivados do endocárdio atrial canino

Yeow Leng Chua, Paulo Roberto Barbosa Evora, Andrea Carla Celotto, Paul Joseph Pearson, Berent Discigil, Hartzell Vernon Schaff
2009 Brazilian Journal of Cardiovascular Surgery  
Adaptação de um sistema de ensaio biológico para detecção de fatores relaxantes endoteliais derivados do endocárdio atrial canino Adaptation of bioassay to detect endotheliumderived relaxing factors from the canine atrial endocardium Abstract Objective: The aim of this study was to assess the release of endothelium-derived relaxing factors from the endocardium of canine atrial appendage. Method: To study the release of endothelium-derived relaxing factor (EDRF) from intact atrial endocardial
more » ... othelium, tube-shaped sutures of canine atrial appendages were performed and effluents from these tubes were bioassayed (isolated perfused organ chamber system) for detection of EDRF in canine coronary artery. Results: Effluent from the right atrial appendage caused a relaxation of 58.4 + 10.1% and the left atrial appendage 74.9 + 8.5% from the initial prostagladin FF2α α α α α contraction in coronary artery. No significant statistical difference was detected in effluent from the right and left atrial appendages. This relaxation was abolished by treating the heart tubes with Triton X-100 and reduced by treatment with LNMMA, a competitive inhibitor of nitric oxide and with indomethacin, an inhibitor of the cyclo-oxygenase pathway, also indicating the release of vasodilatory prostanoids from the endocardial endothelium. Conclusion: This study showed for the first time, in vitro luminal release of EDRF and prostacyclin from the canine heart atrium. The ability of the endocardial endothelium to produce these factors could play an important role in preventing thrombus formation in the cardiac chambers. Descriptors: Heart atria. Endothelium. Nitric oxide. Endocardium Resumo Objetivo: Estudar a liberação de fatores relaxantes derivados do endotélio (EDRF) pelo endocárdio de aurículas de corações caninos. Métodos: Aurículas atriais caninas foram suturadas em forma de tubos e o efluente desses tubos foram submetidos a ensaios biológicos (sistema de perfusão isolada em Study performed at CHUA, YL ET AL -Adaptation of bioassay to detect endotheliumderived relaxing factors from the canine atrial endocardium Bras Cir Cardiovasc 2009; 24(2): 225-232 regulation of receptors when the cells are cultured and the response of the cultured endothelium to agonists can be altered [13, 14] . In the present experiments, a bioassay technique was developed to detect luminal release of endothelium-derived relaxing factors from intact canine atrial endocardium. Rev METHODS Bioassay technique Heartworm free mongrel dogs (25-30 kg; n=10) of either sex were anesthetized with intravenous pentobarbital sodium (30 mg/kg bolus injection; Fort Dodge Laboratories) and exsanguinated via the carotid arteries; the beating heart was excised and immersed in cool, oxygenated physiological salt solution of the following millimolar composition: NaCl, 118.3; KCl, 4.7; MgSO 4 , 1.2; KH 2 PO 4 , 1.22; CaCl 2 , 2.5; NaHCO 3 , 25.0 and glucose, 11.1 (control solution). The procedures and the handling of the animals were reviewed and approved by the Institutional Animal Care and Use Committee of the Mayo Foundation. The left circumflex coronary artery was carefully dissected free from the heart and placed in control solution. A coronary ring of about 3 mm was cut and the endothelium removed with a pair of watchmakers forceps. This procedure effectively removes endothelium from the coronary ring without affecting the smooth muscle ability to contract or relax. Both the right and left atrial appendages were removed as close to its base as possible, and placed in physiological salt solution. The atrium is then sutured into a tube with two layers of continuous 5/O prolene and its ends tied to the bioassay lines. The setup is then checked for leaks and repaired when necessary. The whole suturing process which takes about 10 minutes, was done in a dish containing the control solution and the tissue was kept under solution as much as possible to prevent damage to the endothelium (Figure 1) .
doi:10.1590/s0102-76382009000200020 pmid:19768303 fatcat:m6kgjpmtyfhurl6jbdf4iuitfu