| Part I The Influence of Chronic Intermittent Hypoxia and Reoxygenation on Tissue and Cellular Morphology and Expression of Hypoxia Inducible Factor-la in KidneyObjective To explore the influence of chronic intermittent hypoxia and reoxygenation on tissue and cellular morphology and expression of hypoxia inducible factor-la in kidney of rats.Methods The output flow, time and switching of oxygen and nitrogen of the self-made CIH animal cabin could be adjusted through control procedures, so as to make sure the every hypoxic cycle lasted for 1 minute and the oxygen concentration within the cabin fluctuated between 6～21%.27 rats were randomly divided into three groups with each of nine, CIH group, reoxygenation group and control group respectively. Rats of CIH group were exposed to intermittent hypoxia in the cabin 8 hours per day for successive 35 days. Rats of reoxygenation group were treated the same as CIH group in the first 35 days, while oxygen and nitrogen were replaced by air from the 36th day, lasting 8 hours per day for successive 21 days. Oxygen and nitrogen were replaced by air for rats of control group with other conditions being the same as CIH group. Tissue morphology of kidney was examined through HE dyeing and ultrastructures of proximal tubular cells were observed by transmission electron microscopy. Cellular expression of HIF-la protein was detected by immunohistochemical staining. Total protein content of HIF-la in the kidney was detected by Western blot. Expression of HIF-la mRNA in the kidney was detected by real-time PCR.Results The glomerulus and proximal tubular epithelial cells were highly swelling in CIH group. Glomerular and proximal tubule edema was significantly reduced after reoxygenation of 21 days. The renal tissue morphology of control group was normal. Empty bubble degeneration, nuclear membrane and mitochondria swelling were observed in proximal tubular cells of CIH group. Ultrastructural changes in reoxygenation group were significantly less than CIH group. The renal ultrastructures of control group were normal. The staining of HIF-la protein in proximal and distal tubular cells was stronger in CIH group compared with control group, while significantly reduced after reoxygenation. Relative quantity of HIF-la protein in CIH group, reoxygenation group and control group were 1.72±0.57,1.08±0.39 and 1.03±0.35respectively. The difference between CIH group and control group was significant statistically (p<0.05). The difference between CIH group and reoxygenation group was significant statistically (p<0.05). There was no statistical difference between reoxygenation group and control group (p>0.05). Relative express quantity of HIF-la mRNA in CIH group, reoxygenation group and control group were 22.24±6.49,7.46±2.79 and 3.81±1.72 respectively. The difference between CIH group and control group was and significant statistically (p<0.05). The difference between CIH group and reoxygenation group was significant statistically (p<0.05). There was no statistical difference between reoxygenation group and control group (p>0.05).Conclusion Under the condition of CIH, kidney tissue and cells showed significant edema and kidney levels of HIF-1αprotein and mRNA increased significantly. After reoxygenation, tissue and celluar edema was alleviated accompanied by reduced HIF-1αprotein content and mRNA expression. Chronic intermittent hypoxia is a factor that can lead to renal hypoxia and cell degeneration. Reoxygenations can ameliorate renal hypoxia and cell degeneration and therefore has a therapeutic effect. PartⅡThe Influence of Chronic Intermittent Hypoxia and Reoxygenation on Expression of Neutrophil Gelatinase-Associated Lipocalin in KidneyObjective To explore the influence of chronic intermittent hypoxia and reoxygenation on expression of neutrophil gelatinase-associated lipocalin in kidney of rats.Methods The output flow, time and switching of oxygen and nitrogen of the self-made CIH animal cabin could be adjusted through control procedures, so as to make sure the every hypoxic cycle lasted for 1 minute and the oxygen concentration within the cabin fluctuated between 6-21%.27 rats were randomly divided into three groups with each of nine, CIH group, reoxygenation group and control group respectively. Rats of CIH group were exposed to intermittent hypoxia in the cabin 8 hours per day for successive 35 days. Rats of reoxygenation group were treated the same as CIH group in the first 35 days, while oxygen and nitrogen were replaced by air from the 36th day, lasting 8 hours per day for successive 21 days. Oxygen and nitrogen were replaced by air for rats of control group with other conditions being the same as CIH group. Cellular expression of NGAL protein was detected by immunohistochemical staining. Total protein content of NGAL in the kidney was detected by Western blot. Expression of NGAL mRNA in the kidney was detected by real-time PCR.Results The staining of NGAL protein in glomerular, proximal and distal tubular cells was stronger in CIH group compared with control group, while significantly reduced after reoxygenation. Relative quantity of NGAL protein in CIH group, reoxygenation group and control group were 2.17±0.38,1.75±0.14 and 1.75±0.44 respectively. The difference between CIH group and control group was significant statistically (p<0.05). The difference between CIH group and reoxygenation group was significant statistically (p=0.05). There was no statistical difference between reoxygenation group and control group (p>0.05). Relative express quantity of NGAL mRNA in CIH group, reoxygenation group and control group were 32.30±9.43,8.69±2.76 and 6.16±2.63 respectively. The difference between CIH group and control group was significant statistically (p<0.05). The difference between CIH group and reoxygenation group was significant statistically (p<0.05). There was no statistical difference between reoxygenation group and control group (p>0.05).Conclusion Under the condition of CIH, kidney levels of NGAL protein and mRNA increased significantly. After reoxygenation, NGAL protein content and mRNA expression were both reduced. Chronic intermittent hypoxia is a factor that can lead to renal cell impairment. Reoxygenations can ameliorate renal cell impairment and therefore has a therapeutic effect. |
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