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

Abstract

Adaptação de um sistema de ensaio biológico para detecção de fatores relaxantes endoteliais derivados do endocárdio atrial caninoAdaptation 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 endothelium, 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. 226CHUA, 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 techniqueHeartworm 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 r...

The Left Atrial Appendage Revised

“…In the present model, it could not demonstrate a basal release of EDNO ( i.e. release in the absence of stimulation by an agonist from the intact atrium, as is typically present in other vessels [ 10 ] .…”

“…These cells play the role of a physic-chemical barrier between the cardiomyocytes and the circulating blood [ 7 - 9 ] . Furthermore, just like other types of endothelial cells, EECs release several factors such as nitric oxide (NO), angiotensin II [ 7 ] , endothelin and prostacyclin [ 8 - 10 ] .…”

“…The lateral cannulae were connected to the right and left atrium and the solution perfused thought atrial tubes was dripped on coronary ring. The coronary ring was connected to a force transducer that registers the variation of vascular tone (contraction and relaxation) [ 10 ] . …”

“…2 Representative recording of change in contraction of canine coronary artery ring with endothelium superfused with effluent from atrial appendage tubes infused with A23187. Relaxation was inhibited when the ring was superfused with L-NMMA (A) and when the endothelium was removed (B) [ 10 ] . …”

“…Results are reported as means±SEM. * indicate significant difference between with and without L-NMMA groups (P<0.001) [ 10 ] . …”