| PART ONE THE CHANGES OF AQUAPORINS EXPRESSIONS AND CORRELATIVE MARKS CONCERNING RAT LUNG MATURTION AMONG DIFFERENT AGE OBJECTIVE: Bronchopulmonary dysplasia (BPD) is a kind of chronic lung disease (CLD) influencing children's life quality seriously,death rate is extremely high,the survivors are often accompanied by obvious lung development obstacle and abnormal lung functions. At present the pathogenesis of BPD is not well understood. A large number of researches have shown that the etiological factors were closely correlated with hyperoxia-induced alveolus inflammatory edema and lung fluid transport might participate in development process of BPD. Aquaporins (AQPs) is a kind of cell membrane protein that actively and selectively transports water, which plays an important role in the regulation of tissue liquid transport. AQPs might affect the course of lung tissue development and maturation through regulating its water transportation. We observe several kinds of main AQPs gene expression and its protein localization in lung cell membranes and the content changes of relative marks in the course of lung development and maturation from four different age group of rat, and analyze the change tendency and relativity between them in order to investigate the expression and meaning of AQPs in the course of lung development and maturation. METHODS: The cleanly type wistar rats were divided into Four groups: the E20 (20th-day of the 21 days gestation) group, the 7th-day group, one-month and adult rat group, 8 in each group. The AQP1, AQP3, AQP4 and AQP5 of lung cell membrane proteins were localized and measured by immunohistochemical method (SABC) and the expressions of AQP1, AQP3, AQP4 and AQP5 mRNA in rat lung tissues were detected by Reverse transcription-polymerase chain reaction (RT-PCR). Furthermore, the lung tissue maturation marks (protein and DNA contents, Wet/Dry weight ratio) and morphological structures were analyzed in different group too. RESULTS: 1. Lung morphological structure were clearly observed by HE-stained slices: with the growth of rat age, the cells split and tissues differentiation inparenchymatous tissue, the alveolus numbers increase, the wall becomes thin, lung tissues and blood vessel structure become flawless gradually, which shown a dynamic and successive development course. The protein and DNA contents increase gradually in lung tissues, it is uninterrupted, developing rapidest from fetus rat to newborn rat, afterwards, the growth rate slows down. The lung water content is very high at fetus rat, reducing rapidly to the adult's normal level in one week after birth. 2. Researches manifested through immunohistochemical method (SABC): AQP1 has already weak expression at E20, increasing rapidly to peak level after birth and maintaining at the high expression level to the adulthood, but AQP3, AQP4 and AQP5 has no expression at E20, they all increased rapidly after birth, exhibiting a increasing expression to adulthood. AQP1 is present in lung interstitium, mostly in the apical and basolateral membranes of vascular endothelium cells and interstitial cells. AQP3 is present in basal membranes of tracheal epithelium cells. AQP4 resides in basolateral membranes of bronchial, tracheal epithelium. AQP5 is localized to the apical plasma membrane of type I pneumocytes and secretory epithelium of glands under mucosae. 3. Researches revealed through Reverse transcription-polymerase chain reaction (RT-PCR): AQP1 mRNA has already begun expressed at E20, there are almost three times increase during newborn rat, and afterwards maintaining high expression level to the adulthood. AQP3 and AQP4mRNA expressions were only faint before birth, increased after birth, the increase changes was a linear trend with age growth. AQP5 mRNA expressions were began before birth, it was nearly ten times increase up to newborn period, with age growth it's expressions have several times acceleration rate and entered adulthood. There was a significant statistic difference that they compare with two-two mutually (P<0.01...
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