378 resultados para Oxido nitrico : Pressao arterial : Frequencia cardiaca : Ratos

em Repositório Institucional UNESP - Universidade Estadual Paulista "Julio de Mesquita Filho"


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Purpose - To evaluate the influence of sustained elevations of arterial pressure on dP/dt values, which the left ventricular end diastolic pressure was kept constant. Methods - Thirteen anesthetized dogs, mechanically ventilated and submitted to thoracotomy and pharmacological autonomic block (atropine - 0.5 mg/kg IV + oxprenolol - 3 mg/kg IV) were studied. The arterial pressure elevation was obtained by mechanical constriction of the descending thoracic aorta. Analyses were made in control (C) situation and after two successives increments of arterial pressure, sustained for 10min, called hypertension 1 (H1) and hypertension 2 (H2), respectively. The end diastolic left ventricular pressure was kept constant by utilization of a perfusion system connected to the left atria. Results - Heart rate did not change (C: 125 ± 13.9bpm; H1: 125 ± 13.5bpm; H2: 123 ± 14.1bpm; p > 0.05); the LVSP increased (C: 119 ± 8.1mmHg; H1: 142 ± 7.9mmHg; H2: 166 ± 7.7mmHg; p < 0.01); the AoDP increased (C: 89 ± 11.6mmHg; H1: 99 ± 9.5mmHg; H2: 120 ± 11.8mmHg; p < 0.01); the LVEDP (C: 6.2 ± 2.48mmHg; H1: 6.3 ± 2.43mmHg; H2: 6.1 ± 2.51mmHg; p > 0.05) and the dP/dt (C: 3068 ± 1057.1mmHg/s; 3112 ± 995.7mmHg/s; H2: 3086 ± 979.5mmHg/s; p > 0.05) did not change. Conclusion - dP/dt values are not influenced by a sustained elevation of arterial pressure, when the end diastolic left ventricular pressure is kept constant.

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Silicosis, a common type of pneumoconiosis, is an occupational lung disease caused by inhalation of silica dust often with mining activity and thus reaches the miners. The fine and ultrafine silica particles deposited in the alveolar epithelium may lead to the development of progressive massive fibrosis. An increased reactive oxygen species (ROS) production has been proposed to explain the mechanism for induction of pulmonary fibrosis in silicosis. In this situation, alveolar macrophages are activated to phagocytes silica particles deposited in the alveoli. The activated macrophages secrete large amounts of ROS that in turn induce synthesis of fibrotic factors. In addition, the activity of antioxidant enzymes is impaired, which results in increased lipid peroxidation, as well as generating a local inflammatory process. Diffuse pulmonary fibrosis progresses with interstitial collagen deposition. Interstitial collagen overlies small pulmonary arteries and arterioles and thus it is associated with pulmonary hypertension in pulmonary fibrotic diseases. In addition, cytokines and silica particles passing through the respiratory membrane can reach the bloodstream. In this context, the increase in the generation of ROS in the circulation may lead to a reduction in the bioavailability of nitric oxide, an important endothelium-derived relaxing factor. A deficiency in the nitric oxide bioavailability can result in vascular endothelial dysfunction. Moreover, pro-inflammatory cytokines could contribute to the impairment of endothelial function. In the airways, pro-inflammatory cytokines can reduce the smooth muscle responsiveness to β- adrenergic agonists as isoproterenol. Thus, the aim of this study was to evaluate the effect of silica dust instillation in the function of the pulmonary artery, aorta and trachea of rats with acute silicosis. For this purpose, male Wistar rats were anesthetized... (Complete abstract click electronic access below)

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