Objective To study the effects of hyperoxia on ventilator-induced lung injury(VILI) in rats.Methods 48 healthy male SD rats were randomly divided into four groups:Group A received conventional mechanical ventilation(VT=8 mL/kg) with room air,Group B received the same tidal volume as group A with 100% O2,Group C received large tidal volume(VT=40 mL/kg) with room air,group D received the same tidal volume as group C with 100% O2.Arterial blood gases were measured every one hour and oxygenation index(PaO2/FiO2) was calculated.The changes of lung histopathology were assessed by HE staining and observed under light microscope.Wet-to-dry weight ratio(W/D) of left lung,neutrophils and white blood cell(WBC) counts in BALF were measured.TNF-α,IL-1β,and MIP-2 levels in BALF,malondialdehyde(MDA),myeloperoxidase(MPO),and superoxide dismutase(SOD) levels in the lung were assayed,respectively.Results Compared with the Group C,the Group D demonstrated more infiltrating neutrophils in the lung and more destructive changes in the alveolar wall.Meanwhile,the oxygenation index decreased,the WBC and neutrophils counts in BALF increased,and the W/D of left lung was higher in the Group D with significant differences compared with the Group C.Moreover,the BALF levels of TNF-α,IL-1β and MIP-2,the lung levels of MDA increased,and the lung levels of SOD decreased significantly in the Group D compared with those in the Group C.There were no statistical significant differences between the Group B and Group A in all parameters except that MDA levels increased and SOD levels decreased significantly in the Group B.Conclusion Hyperoxia can increase lung injury induced in large tidal volume ventilation in rats,but has mininmal effects in conventional mechanical ventilation.
Ojective To establish a rat model of hyperoxia induced acute lung injury. Methods Eighty healthy male SD rats were randomly divided into an air group and a hyperoxia group ( ≥95% O2 ) .Each group was further divided into 12 h, 24 h, 36 h, 48 h, 60 h subgroups. Arterial blood gas was monitored. Lung tissue was sampled for evaluation of lung wet to dry ratio, lung index, and pulmonary permeation index. Bronchoalveolar lavage fluid ( BALF) was collected for measurement of lactatedehydrogenase ( LDH) activity and white blood cell count ( WBC) . Results After hyperoxia exposure for 48 ~60 h, lung pathology showed alveolar structure disruption, lung parenchyma wrath bleeding and edema.Lung wet to dry ratio, lung index, pulmonary permeation index, LDH and WBC in BALF all increased significantly, peaked at 48 h and remained at high level at 60 h while PaO2 dropped progressively.Conclusion Exposure to ≥ 95% O2 for 48 ~60 h can successfully establish the rat model of hyperoxia induced acute lung injury.
Objective To investigate the effects of recombinant human erythropoietin ( rHuEPO) on expressions of Bax and Bcl-2 proteins in hyperoxia-induced lung injury of adult rats. Methods Fortyeight healthy male SD adult rats were randomly divided into six groups. The control group ( 0 h) breathed with room air. The rHuEPO intervention group was put into oxygen chamber and breathed with 100% O2 for 96 h plus intraperitoneal injection of rHuEPO (1000 U/kg) daily. Other four groups were put into oxygen chamber and breathed with 100% O2 for 24, 48, 72 and 96 h respectively. Arterial blood gases were measured to calculate oxygenation index. Wet-to-dry weight ratios of left lung were measured. The contents of TNF-α and IL-1β in bronchoalveolar lavage fluid (BALF) were assayed with radioimmunoassay. The expressions of Bax and Bcl-2 proteins in the lung were determined withWestern blot and immunohistochemisty. The changes of lung histopathology were assessed by hematoxylin and eosin stain and observed under light microscope. Results After breathing 100% O2 , the oxygenation index decreased gradually and reached minimal value at 96 h. The wet-to-dry weight ratio of left lung increased gradually and reached maximal value at 96 h. The contents of TNF-α and IL-1β in BALF reached maximal value at 48 h and then decreased gradually. The expression of Bax protein increased, but the expression of Bcl-2 protein decreased gradually in the lung. Compared with the 96 h group, the oxygenation index was higher, wet-to-dry weight ratio and contents of TNF-α and IL-1β in BALF decreased, the expression of Bax protein decreased, and the expression of Bcl-2 protein increased in the lung of the rHuEPO group. Conclusion rHuEPO can attenuate hyperoxia-induced lung injury of adult rats by down-regulating expression of Bax protein and up-regulating expression of Bcl-2 protein.
Abstract: Objective To investigate the cerebral protective effects of hyperoxia management during deep hypothermia circulatory arrest(DHCA) rabbit by the blood gas indexes, superoxide dismutase( SOD) activity and malondialdehyde (MDA) levels of brain, and ratio of water to brain. Methods A DHCA and antegrade selective cerebral perfusion (ASCP) rabbit model was established. Twenty-four 11-13 week-old male New Zealand rabbits( weighing 2.7 to 3.4 kg) were assigned to three groups with a random number table: a sham operation group (Sham group), an ASCP group (S group), and an ASCP + hyperoxia management group (SH group). There were eight rabbits in each group. We recorded the intraoperative values for arterial oxygen pressure (PaO2), arterial oxygen saturation (SaO2), jugular venous oxygen pressure(PjvO2), jugular venous oxygen saturation( SjvO2) and blood lactate level. The brain SOD activity, MDA levels, and ratio of water to brain were measured after the operation. Results Before initiating circulatory arrest, before initiating reperfusion and five minutes of reperfusion, levels of PaO2 , PjvO2 , and SjvO2 in the SH group were significantly higher than those of the S group and Sham group. SOD activity in the SH group was not significantly different from that of the S group[(213.53±33.52) U/mg. prot vs. (193.02±27.67) U/mg. prot] and Sham group[(213.53±33.52) U/mg. prot vs.(244.38±35.02)U/mg. prot], but the SOD activity in the S group was lower than that in the Sham group( P < 0.05). MDA levels in the SH group were lower than that in the S group[(1.42±0.30) nmol/mg. prot vs. (2.37±0.55) nmol/mg. prot, P < 0.05]. Conclusion Our data show that hyperoxia management during DHCA+ASCP improves rabbits’PjvO2 and SjvO2, maintains brain SOD activity, and decreases brain MDA levels, demonstrating the neuroprotective effects of hyperoxia mangagement.
ObjectiveTo explore the role of osteopontin (OPN) in hyperoxia-induced acute lung injury and its relationship with nuclear factor-κB (NF-κB),matrix metalloproteinase 2 and 9 (MMP-2,MMP-9). MethodsNinety-six mice were randomly divided into a phosphate buffer solution intranasal inhalation group (PBS group) and a recombinant OPN intranasal inhalation group. The mice were exposed in sealed cages >95% oxygen for 24-72 hours to induce lung injury or room air as control. The severity of lung injury was evaluated. The expression of NF-κB,MMP-2,MMP-9,TIMP-1 and TIMP-2 mRNA in lung tissue at 24,48 and 72 hours under hyperoxia were examined by reverse transcript-polymerase chain reaction (RT-PCR). Immunohistochemistry (IHC) was performed for detection of NF-κB protein in lung tissue. ResultsPBS group mice developed more severe acute lung injury at 72 hours under hyperoxia.TIMP-1 and TIMP-2 mRNA expressions were significantly increased in r-OPN group than their matched PBS group when exposed to hyperoxia. IHC study showed higher expression of NF-κB protein in lung tissue of PBS group at 72 hours of hyperoxia. ConclusionOPN can protect against hyperoxia-induced lung injury by inhibiting the expressions of NF-κB,MMP-2 and MMP-9.
ObjectiveTo investigate the effects of short-time hyperoxia ventilation on lung tissue and pulmonary surfactant proteins C and D (SP-C and SP-D) in rats.MethodsSixteen male Sprague-Dawley rats were randomly divided into two groups (n=8): hyperoxia group (FiO2=0.90), air group (FiO2=0.21). Tracheal intubations were administrated after anesthesia, and rats in two groups were exposed hyperoxia or air ventilation for 4 h. At the same time, carotid artery blood gas was analyzed after 2 h and 4 h of ventilation, then oxygenation index (OI) was calculated. Four hours later, the anterior lobe of right lung was taken to observe the pathological change and the injury level was scored. The middle lobe of right lung was prepared for making tissue homogenate, and the remaining part of the lung was used to measure the wet/dry weight (W/D) ratio. The bronchoalveolar lavage fluid (BALF) was prepared in left lung. The content of SP-C and SP-D were detected in lung tissue homogenate and BALF by ELISA.ResultsComparing with hyperoxia group, the arterial partial pressure of oxygen, lung histopathology score and lung W/D ratio in air group were significantly increased (P<0.05), but OI, the content of SP-C and SP-D in lung tissue homogenate and BALF were significantly decreased (P<0.05).ConclusionHyperoxia ventilation for 4 h in rats can cause lung injury histologically, and reduce the concentration of SP-C and SP-D apparently in the lungs.
ObjectiveTo investigate the effect of succinate induced polarization of MH-S murine alveolar macrophage cells on hyperoxia-induced epithelial-mesenchymal transition (EMT) of MLE-12 mouse alveolar epithelial cells. Methods Determine the exposure time: MLE-12 cells was cultured in an incubator with 95%O2 for different time to establish a cell model of acute hyperoxia-induced lung injury. The relative expression of EMT-related proteins (E-cadherin, N-cadherin, vimentin) was determined by Western blotting. Co-culture of MLE-12 and MH-S to explore the influence of MH-S on EMT: MLE-12 was divided into hyperoxia group for 0h, hyperoxia group for 48h and co-cultured with MH-S hyperoxia group for 48h (Co). The relative expression of EMT-related proteins was determined by Western blotting. Determination of succinate concentration and its effect on MH-S polarization and succinate receptor GPR91: MLE-12 was cultured in different concentrations of succinate medium for 24h, and the cell viability was determined by CCK-8. MH-S was divided into control group (C) and succinate group (S). Group C was cultured for 24h, and group S was added with succinate at the above concentration. The relative expression of GPR91 and polarization-related factor mRNA in MH-S was measured by RT-qPCR, and the expression of macrophage polarization-related proteins (CD11b, CD206, CD86) was measured by flow cytometry. Study on the effect of succinate on EMT by cell co-culture: MLE-12 and MH-S were co-cultured in a Transwell chamber and divided into control group (Co), succinate group (SUC) and GPR91 inhibitor group (I). Results Expression of EMT-related proteins in four groups of MLE-12 at different times: Compared with 0h, the expression of vimentin and N-cadherin in 24h and 48h increased, while the expression of E-cadherin in 48 h and 72 h decreased (P<0.05), and there was no significant difference in other groups. The follow-up experiment was conducted under hyperoxia conditions for 48h. Influence of MH-S on EMT: The expression of vimentin and N-cadherin in Co group was higher than that in 48h, and the expression of E-cadherin was lower than that in 48h (P<0.05). After 24 h of intervention with different concentrations of succinate on MLE-12, compared with the 0mmol/L, the cell viability of 2.5mmol/L, 1mmol/L and 500 μmol/L increased (P<0.05), and there was no significant difference in other groups, so the 1mmol/L succinate concentration was selected for subsequent experiment. Compared with group C, the expression of GPR91 mRNA in group S increased, and the expression of iNOS and CD86 mRNA in group S increased (P<0.05), but there was no significant difference in other groups. The analysis of flow cytometry showed that 1mmol/L succinate could increase the number and proportion of CD86+CD206– alveolar macrophages. Compared with Co group, the expression of vimentin and N-cadherin in SUC group increased, while the expression of E-cadherin decreased. Compared with SUC group, the expression of vimentin and N-cadherin in group I decreased, while the expression of E-cadherin increased (P<0.05). Conclusion Succinate can induce mouse alveolar macrophages polarization to M1 through GPR91, enhance EMT of mouse alveolar epithelial cell injury model under hyperoxia, and promote the formation of pulmonary fibrosis.