Treatment Effect Of Epidermal Growth Factors On Rats With Smoke Inhalation Injury

Objective: Through observing the therapeutical effect on smoke inhalation injury on rats with different doses of epidermal growth factor, which are infused in their airways, the doses and the method of epidermal growth factor can be determined and the reference for clinical treatment programmes (dosage, usage) can be provided.Methods: The study was divided into two parts: 1. Rat model of smoke inhalation injury: rats were randomly divided into 7 groups——control group and six experiment groups in which rats were killed in 1h, 6h, 12h, 24h, 48h, 72h after inhalation injury. Rats were vulnerated in a special device smoke injuries. To evaluate the effect of smoke inhalation injury model through multiple factors: blood gas analysis, lung index, gross morphometric and pathological obserevation, the count of total number of cells, macrophages, neutrophils, lymphocytes, red blood cells, epithelial cells and protein concentration in bronchoalveolar lavage fluid.2. To observe therapeutic efficacy of different doses of epidermal growth factor on rats: Rats were randomly divided into four groups——control group, low dose group(100ug/kg), medium dose group (150ug/kg) and high dose group (200ug/kg), normal sodium and different concentrations of epidermal growth factor(50ug/ml, 75ug/ml, 100ug/ml) 2ml/kg were dropped into airways of rats respectively, BrdU (100mg/kg) was intraperitoneal injected after 12 hours. Rats were killed after 72h and therapeutic efficacy was evaluated through multiple factors: blood gas analysis, lung index, gross morphometric and pathological obserevation , the count of total number of cells, macrophages, neutrophils, lymphocytes, red blood cells, epithelial cells and protein concentration in bronchoalveolar lavage fluid. And we estimated epidermal growth factor on airway epithelial cell proliferation through observing immunohistochemical staining of BrdU.Results: 1 .This model of smoke inhalation injury on rats achieves the desire. Blood gas analysis showed that: PH was on a downward trend, and there was significant difference between the groups of 12h, 24h, 48h, 72h after injury and the control group, and PH was the lowest 24h after inhalation injury. PaO₂ decreased significantly while there was significant difference between the groups of 1h,6h,12h, 24h, 48h, 72h after injury and the control group. PaCO₂ was on a upward trend, and there was significant difference between the groups of 24h, 48h, 72h after injury and the control group. There was significant difference between the groups of 12h, 24h, 48h, 72h after injury and the control group in lung index. Lung index reached the peak in 24h after injury, then reduced gradually. Bronchoalveolar lavage fluid: Total number of cells greatly increased after 12h. Macrophage cells, red blood cells significantly increased after 24h.Neutrophils, lymphocytes significantly increased after 6h.Epithelial cells significantly increased at 48h. Protein concentrations in bronchoalveolar lavage fluid of control group was (11.303±5.634)ug/ml, it was on upward trend after injury, [46.956±15.175, P <0.05)] at 48h, [(60.781±35.354, P <0.01)] at 72h, respectively. 2. Saline and different doses of epidermal growth factor were dropped into the airway of rats after injury, and the results demonstrated: PH was on a upward trend with the dose increasing, and there was significant difference between medium dose group, high dose group and control group. PaO₂ was on the upward trend, and PaCO₂ was on a downward trend. There was significant difference between medium dose group, high dose group and control group. PaO₂ of high dose group increased obviously compared with that of low dose group. Lung index and protein concentrations in bronchoalveolar lavage fluid were on downward trend with the doses of epidermal growth factor increased. There was a significant difference between medium dose group, high dose group and control group, but low dose group had no significant differences. Bronchoalveolar lavage fluid: the total number of cells, macrophages, neutrophils, lymphocytes of three treatment groups significantly decreased compared with the control group. Red blood cells and epithelial cells of medium dose group and high dose group significantly decreased compared with the control group. Labeling index of three treatment groups was on the upward trend, high dose group significantly increased compared with the control group and low dose group.Conclusion: smoke inhalation injury can lead to pulmonary edema, airway inflammatory infiltration and cell damage. Exogenous epidermal growth factor can remove pulmonary edema, inhibit airway inflammation, promote the proliferation and repair of epithelial injury, and restore the form and function of epithelial integrity. With the increase of doses ,the effects are more obvious.