RESUMEN
Objective To investigate the signal pathway of platelet activation in acute respiratory distress syndrome (ARDS). Methods Thirty healthy Sprague-Dawley (SD) rats were randomly divided into control group (n = 6) and model group (n = 24). The model of ARDS was reproduced by intravenous injection of oleic acid (0.25 mL/kg), and the rats in control group were injected with the same amount of normal saline. The blood of abdominal aorta was collected at 2, 6, 24, and 72 hours after model reproduction, the platelets were separated, and c-Jun N-terminal kinase phosphorylation (pJNK) levels which was one of major protein kinases in the mitogen-activated protein kinases (MAPKs) signal pathway was determined by Western Blot. The rats were sacrificed, the lung tissues were harvested, and lung coefficient (lung weight/body weight ×100%) and lung wet/dry (W/D) ratio were calculated. Pathological changes in the lung tissue were observed with hematoxylin-eosin (HE) staining in light microscope. Results Comp ared with the control group, platelet pJNK level in ARDS model group was significantly increased at 2 hours after model reproduction (gray value: 0.72±0.09 vs. 0.22±0.01), and peaked at 6 hours (gray value: 0.91±0.03 vs. 0.22±0.01), then it was decreased gradually. It was also significantly higher than that of control group till 72 hours after model reproduction (gray value: 0.39±0.06 vs. 0.22±0.01, all P < 0.05). Lung coefficient and lung W/D ratio in ARDS model group were significantly increased at 2 hours after model reproduction as compared with those of control group [(1.30±0.20)% vs. (0.60±0.10)%, 6.00±0.60 vs. 3.30±0.30], then they were decreased gradually. They were also significantly higher than those of control group till 72 hours after model reproduction [(0.90±0.10)% vs. (0.60±0.10)%, 4.80±0.70 vs. 3.30±0.30, all P < 0.05]. It was showed by light microscopy that lung tissue of rats in the control group had no significant pathological changes. At 2 hours after model reproduction in model group, clearly visible alveolar edema and interstitial edema, interstitial lung infiltration of inflammatory cells, small blood vessels dilation and congestion were found, and the re were a lot of protein exudates. The lesions of lung peaked at 24 hours. At 72 hours, absorption of most of fluid leaking in alveolar, alveolar space narrow, alveolar septum thickening, the reduction of inflammatory cells infiltration, fibrous tissue proliferation, and micro thrombosis formation were found. Conclusion In ARDS, in addition to pathological changes in the lung tissue, platelet activation occurs, and its activation process is related to the priming of JNK signal transduction pathways.