Study of the effects of hypertonic saline solution on microcirculatory and cardiac tissue changes, and development of the inflammatory process in a rat model of brain death

Abstract

In previous studies it has been shown that brain death itself induces hypoperfusion in the mesenteric microcirculation that is associated with a pronounced reduction in the endogenous corticosterone level, thereby leading to increased local inflammation and organ dysfunction. Furthermore, the autonomic storm does not seem to be responsible for the inflammatory changes associated with brain death, since thoracic epidural anesthesia does not modify the expression of inflammatory mediators, although it effectively blocks the autonomic storm. This study aims to investigate the effects of hypertonic saline solution (7.5%) on microcirculatory changes through the in vivo and in situ observation of the mesenteric microcirculation, and the development of the cardiac and mesenteric inflammatory process in a rat model of brain death. The design includes the investigation of: (1) blood flow, vascular density and leukocyte-endothelial interactions in the mesenteric microcirculation by intra-vital microscopy; (2) expression of P-selectin, ICAM-1, and VCAM-1 on mesenteric microvessels by immunohistochemistry; (3) expression of e-NOS, i-NOS, and endotelin-1 by immunohistochemistry and by real time RT-PCR on the mesentery; (4) expression of ICAM-1 and VCAM-1, caspase-3 and Bcl-2, and a-actin on cardiac tissue by immunohistochemistry; (5) serum and cardiac levels of cytokines by ELISA; (6) serum levels of corticosterone by ELISA; (7) hemodynamic and respiratory parameters, blood gases, electrolytes, and lactate. (AU)