A Study On The Morphologic Changes And Injury Mechanism Of The Lung, Heart And Brain In The Oleic-Induced Ards Rats

Objectives To probes the morphologic changes and its injury mechanism of the lung, heart and brain in the oleic-induced ARDS rats; to provide the theoretic basis for the clinic treatment on ARDS patients. Methods 15 Pure Wistar rats were divided into the experiment and the control group randomly. The amount of 0.1ml/Kg oleic acid were injected through lingua vein in the experiment group (n=10); and the same amount of N.S were injected instead in the control group (n=5). Rats were killed after 2 hours and the cerebral cortex, lung tissue and right atria were obtained. The morphologic changes of these three tissues were observed with light microscope and transmission electronic microscope; the pulmonary wet-to-dry weight ratio, the pulmonary weight indexs, and the ratio of the area of the multilamellar body to the area of cytoplasm in type II alveolar cell were measured.Results 1.The permeability of the pulmonary endothelial cells increased 2 hours after the injection of oleic acid. Ultrastructure revealed increased amount of micropinocytosis vesicles, swelling of endothelial cells and apoptosis; the swelling of pulmonary epithelial (type I and type II), the reduced amount of multilamellar body with significant cavitation; the alveolar cavities were infiltrate with large amount ofplasma, fibrin substance and blood cells; mild pulmonary interstitial hyperplasia and infiltration of inflammatory cells (predominantly polymorphonuclear leukocyte). 2. The myocardic cells: slight dissolution of nucleus, dotted dissolve of myofilament, mild swelling of the inner chamber of mitochondria, mildly enlarged saroplasmic reticulun; SAG reduced or disappeared; margination or pycnosis for the heterochromatin of endothelial cells nucleus, heavier change of the electronic density of plasm, with some cavitation.3.The brain tissues: some neurons were swelling in different degree, which displayed to be the mild dissolve of nucleus and swelling of plasma (mostly for the neuron near the capillaries); significant edema at the pericapillaries area, the endothelial cells showed only increased amount of micropinocytosis vesicle, with normal tight junction. Conclusions 　1.The basic morphological changes of the oleic-induced ARDS lungs among rats was that: oleic acid directly injured pulmonary capillary endothelial cells and alveolar epithelium, resulted in the infiltration of plasma and blood cells into the alveolar lumen, led to the reduction of PS in the alveolar type II cells, and cause to the collapse of the alveolar lumen and disability of lung function, and produce progressive hypoxemia.2. The ultrastructure of myocardium capillary endothelial cells and myocardial cells displayed to be an anoxia change 2 hours later after the oleic injection. This change might be related to progressive hypoxemia resulted from ARDS. In addition, as apoptosis of capillary endothelial cells were observed. 3.Neurons and capillary endothelial cells of cerebral cortex were swelling and mildly dissolved 2 hours later after the oleic induced ARDS in rats. At the mean time, there was an increase of water around thecapillaries. All of these changes may related to the secondary progressive hypoxemia.