The Expression SP–C In Lung Of COPD Rat

Background chronic obstructive pulmonary disease?COPD?is a chronic airway inflammatory disease characterised by progressive respiratory airflow obstruction that is not fully reversible,which is associated with chronic airway inflammation,Symptoms include chronic cough,sputum,asthma,and so on.The most commonly encountered risk factors for COPD are tobacoo smoking and noxious particles or gases of inhaled gas.Chronic inflammatory injury such as pulmonary interstitial hyperplasia,alveolar epithelial cells degeneration,and decreased compliance is the prerequisite of pulmonary disfunction.Surfactant Protein C?SP-C?which is one of main components of pulmonary surfactant is closely related to pulmonary compliance.This research establish a COPD rat model by passive smoking + intratracheal LPS instillation,the main testing index is SP-C.Objectives The paper mainly studied COPD rats,we obversed oxygen?PaO₂?and carbon dioxidemeasure arterial partial pressure?PaCO₂?,the levels of SP-C and pro SP-C in bronchoalveolar lavage fluid?BALF?,SP-C protein and m RNA expression.The study investigated the effect of SP-C changes of COPD rats on respiratory function and its mechanisms.Methods Forty healthy conventional Sprague-Dawley?SD?rats were randomly divided into four groups,normal control group?control group?,smoke exposure group?smoking group?,lipopolysaccharide group?LPS group?,smoke exposure+Lipopolysaccharide group?COPD group?.Rats of normal group,were done nothing expect normal feeding.In smoking group,rats were placed in a 60 x 40 x 30 cm smoke exposure box for 30 min,twice daily,for 28 consecutive days.In LPS group,LPS was administered at 1 mg/kg by intratracheal instillation on days 1 and 14?1d and 14d?.In COPD group,rats were treated by smoke exposure 30 min twice daily for 28 days,andintratracheal instillation of 1 mg/kg LPS on days 1 and 14?1d and 14d?.On day 29?29d?,all rats were anesthetized by intraperitoneal injection of 4% chloral hydrate at 10 mL/kg and an incision was made below the xiphoid process.A 5-mL article sample was collected from unilateral common carotid arteriy.Then rats were sacrificed.Completing the following experiments?1?Testing PO₂ and PCO₂ by enzyme-linked immunosorbent assay,?2?Testing an expression level of SP-C in lung tissue,?3?Observing the ultrastructure of lung tissue by transmission electron microscope,?4?Observing SP-C mRNA level by reverse transcriptionpolymerase chain reaction?RT-PCR?.Result?1?The result of PaO₂ and PaCO₂: The arterial partial pressure of oxygen of COPD group was lower than smoke group,that of smoke group was lower than LPS group,that of LPS group was lower than normal group.The arterial partial pressure of carbon dioxide of COPD group was higher than smoke group,that of smoke group was higher than LPS group,that of LPS group was higher than normal group.?2?The ultrastructure changes of type?alveolar epithelial cells: There were Surface microvillus decreased significantly,the lamellar bodies vacuolization,mitochondrial swelling with or without crista rupture in COPD group.There were Surface microvillus slightly reducing,part of the lamellar bodies vacuolization,structure of mitochondria almost normal,mitochondrial swelling without crista rupture in smoke group.There were Surface microvillus almost normal,the lamellar bodies without vacuolization,structure of mitochondria almost normal,mitochondrial swelling in LPS group.There were normal Surface microvillus,the normal lamellar bodies,mitochondria with normal structure and normal mitochondrial swelling in normal group.?3?The content of SP-C in BALF: The content of SP-C in BALF of COPD group rats was lower than that of smork group rats.The content of SP-C in BALF of smork group rats was lower than that of LPS group rats.The content of SP-C in BALF of LPS group rats was lower than that of normal group rats.?4?The content of SP-C in lung tissue homogenate: the content of SP-C of COPD group was lower than that of smork group,that of smork group was lower than that of LPS group,that of LPS group was lower than that of normal group.?5?Reverse transcription-polymerase chain reaction results : the level of SP-C of COPD group was lower than smork group,that of smoke group was lower than that of LPS group,that of LPS group was lower than that of normal group.All above results have statistical significance.P<0.05.Conclusion1.There is the structural damage of type ? alveolar epithelial cells in the rat with chronic obstructive pulmonary disease,and this structural damage can reduce the expression of SP-C.2.It is one of the important role of lung ventilation dysfunction that this structural damage can reduce the expression of SP-C in rats with chronic obstructive pulmonary disease.