Efeitos macrovasculares, microvasculares e interação leucócito-endotélio, na endotoxemia experimental após o uso de Dobutamina com e sem ressuscitação volêmica / Macrovascular and microvascular effects and leukocyte-endothelial interaction in experimental endotoxemia after use of dobutamine with and without volume ressuscitation

Na sepse, o mecanismo desencadeador de morte é a disfunção múltipla de órgãos e sistemas. Com isso a microcirculação é considerada o motor na patogênese da sepse. A perfusão microcirculatória representa um dos principais objetivos para melhorar as taxas de sobrevida. Uma vez reconhecida a síndrome séptica, o protocolo clínico estabelece o uso de fluidoterapia com salina, de forma vigorosa na primeira hora e seguida de suporte inotrópico com Dobutamina. A partir daí foi levantada a hipótese das drogas β-agonistas serem relevantes na recuperação da microcirculação, antes mesmo de seu conhecido papel na recuperação do choque cardiogênico. Assim, estudar o papel da Dobutamina, um β-agonista, na resposta adrenérgica em situação de sepse se faz necessário e urgente e o entendimento de sua ação, associada à reposição volêmica, foi objeto deste estudo. Foram usados no presente estudo, 78 hamsters, induzida a endotoxemia com LPS (2mg/kg/de massa de peso corporal) e divididos em 9 grupos: controle (n=10), endotóxico(n=10), endotóxico tratados com Dobutamina na dose de 5 e 15 μg /kg/min (n=10), Isoproterenol(n=10), ressuscitação volêmica (n=10) e ressuscitação volêmica associada à Dobutamina 5 (n=10) e 15 μg/kg/min (n=4) e Isoproterenol (n=4). Foram comparados os resultados de recuperação da densidade capilar funcional ao longo do tempo entre os grupos, e obteve-se resultado estatisticamente significativo no grupo em que se usa Dobutamina de 5μg/kg/min associada à ressuscitação volêmica p< 0,05. Em conclusão este estudo mostra que o papel da ressuscitação volêmica é crucial na resposta da microcirculação para melhorar a densidade capilar funcional, que a velocidade da hemácia capilar tem relação direta com a melhora na perfusão tecidual e que a associação de recuperação volêmica com solução salina e Dobutamina na dose de 5 μg /kg /min melhora significativamente sua resposta e melhora a perfusão.

uring sepsis the mechanism responsible for death is multiple dysfunctions of organs and systems and therefore the microcirculation is considered the motor in the pathogenesis of sepsis and microcirculatory perfusion represents one of the main objectives to improve survival rate. Once one recognizes the septic syndrome, the clinical protocol establishes the use of fluid therapy with physiological saline, in a vigorous way, in the first hour followed by inotropic support with dobutamine. With these facts in mind, our hypothesis is that β-agonist drugs are relevant for microcirculatory recuperation, even before their role was known in the recuperation of cardiogenic shock. In this way, to study the role of dobutamine, a β-agonist, in the adrenergic response in sepsis is needed and urgent. The understanding of its action associated to volume resuscitation was the aim of our study. Seventy-eight male hamsters were used in our study, endotoxemia being induced with LPS (2 mg/kg body weight), divided in 9 groups: control (n=10), endotoxic (n=10), endotoxic treated with dobutamine in the concentrations of 5 and 15 μg/kg/min (n=10, each), isoproterenol (n=10), volume resuscitation associated to dobutamine 5 μg/kg/min (n=10), 15 μg/kg/min (n=4), isoproterenol (n=4) or not (n=10). The microcirculation was observed in the dorsal window chamber and the results compared the recuperation of function capillary density with time and the group treated with dobutamine 5 μg/kg/min associated to volume resuscitation showed a statistically significant improvement (p<0.05) of it. In conclusion, this study has shown that volume resuscitation plays a crucial role in the microcirculatory response in terms of improvement of functional capillary density, the velocity of red blood cells in the capillary has a direct relationship with the improvement of tissue perfusion and the association of volume resuscitation with physiological saline and dobutamine 5 μg/kg/min elicits ...

A novel femur window chamber for in vivo studies of bone microcirculation

Background: Due to technical difficulties of in vivo observation of blood flow and microvessels in bone, no study has been done concerning the role of blood flow in bone remodeling. Objective: To develop a new window chamber for microscopic observation of the microcirculation in living bone, and to examine the utility of the chamber using rat femur in health and diseases. Methods: A stainless chamber (19 mm in diameter and 5 mm in height) with a circular window (7.5 mm in diameter) for microscopic observation was developed. The chamber was put on rat femur which was exposed for direct observation of the microvasculature. Intravital observation was made of bone blood flow and microvessels, using fluorescence videomicroscopy and confocal laser microscopy. The utility of the chamber was examined based on images of microcirculation (normal and abnormal) in the femur bone. Results and conclusions: Images of rat femur microvasculature were enhanced in the quality by use of the femur window chamber. The new chamber provides a powerful tool for in vivo studies of the bone microcirculation in health and diseases.