Abstract

This thesis establishes and validates an experimental animal model to analyse leukocyte recruitment and microvascular dysfunction in pulmonary ischemia/reperfusion injury by intravital fluorescence microscopy in the rat. The pleural surface of the rat left lung has been exposed by atraumatic microsurgical techniques and fluorescence epi-illumination was used to visualize subpleural pulmonary microcirculation under baseline conditions and during reperfusion after 30 min of ischemia. The results show that this experimental setup bears the required spatial and temporal resolution to study postischemic leukocyte responses within the pulmonary microcirculation. All segments of pulmonary microvascular tree can be differentially analysed, including feeding arterioles, alveolar capillaries and draining postcapillary venules. The data analyses demonstrate that the relatively mild ischemic insult of 30 min provokes a detectable leukocytic response, i.e. significantly increased leukocyte- endothelial cell adhesive interactions in postcapillary subpleural pulmonary venules during reperfusion. Microhemodynamics were not significantly altered during reperfusion. These results translate into the histopathological analyses, confirming mild affection of the pulmonary tissue structures after 90 min of reperfusion. Confirming i) the relatively mild ischemic insult to the lung and ii) virtual absence of trauma by the microsurgical preparations, remote organ damage was basically absent the heart and kidney, but only minimally seen in the liver. In conclusion, the established experimental setup allows for reproducible analyses pulmonary ischemia/reperfusion injury on the microcirculatory level in the rat lung. The use of this basic approach may serve as a reliable basic model for further studies on pulmonary ischemia/reperfusion injury and experimental allo- and xenogeneic lung transplantation.