RESUMO
Objective To observe the effect of exposure of emphysema with intermittent hypoxia on oxidative stress injury of myocardial cells in rats. Methods Sixty male Wistar rats were divided randomly into four experimental groups(each n=15). The normal control group was bred normally. The emphysema group was exposed to cigarette smoke twice a day(once 30 minutes). The intermittent hypoxia(IH)group was exposed to intermittent hypoxia circumstance 8 hours/day,and the emphysema with IH group was exposed to cigarette smoke twice a day (once 30 minutes)and intermittent hypoxia circumstance 8 hours/day. Each group was exposed for 8 weeks. At the beginning of 9 weeks,the blood gas analysis was performed in 5 rats selected randomly from each group,and the rest rats were sacrificed and their hearts and lungs were taken. Under light microscope,the lung tissues stained with hematoxylin-eosin(HE)were examined. The lung pathology and the results of blood gas analysis showed that the emphysema with IH rat model was established successfully. The levels of malonaldehyde(MDA)and superoxide dismutase(SOD)in rat myocardium were measured by enzyme-linked immunosorbent assay(ELISA),and the subunit p22phox mRNA expressions of nicotinamide adenine dinucleotide phosphate(NADPH)-oxidase were detected by real-time reverse transcription-polymerase chain reaction(RT-PCR). Results Compared with the normal group, the MDA levels and p22phox mRNA expressions were increased obviously in emphysema group, IH group and emphysema with IH group〔MDA(μmol/g):2.93±0.54, 3.58±0.63, 4.51±0.72 vs. 1.75±0.56, p22phox mRNA:0.043±0.004,0.067±0.015,0.123±0.016 vs. 0.018±0.002,all P<0.05〕,but the activities of SOD were decreased significantly(U/mg:36.07±4.79,33.51±7.12,24.29±5.36 vs. 46.08±5.12,all P<0.05). In emphysema with IH group,the increase of MDA levels and p22phox mRNA expressions and decrease of SOD levels were more remarkable compared with those in emphysema group and IH group(all P<0.05). The expression of p22phox mRNA was positively correlated with MDA level(r=0.734,P<0.001). Conclusion The myocardial tissue oxidative stress injury in rats induced by emphysema with intermittent hypoxia exposure is more serious than that induced by exposure of either emphysema or intermittent hypoxia alone,NADPH oxidase possibly being the important medium of myocardial cell response to oxidative stress.
RESUMO
Objective To investigate the effect of intermittent hypoxia (IH) with pulmonary emphysema on the ex-pression of hypoxia inducible factor-1α(HIF-1α),Bax and Bcl-2, and the mechanism underlying the role of HIF-1αin he-patocyte apoptosis thereof. Methods Sixty rats were randomly divided into four groups: normal control group, rats were treated normally;IH group, rats were treated by 30 s nitrogen and then 90 s air, and rats were treated by from 9:00-17:00 daily;pulmonary emphysema group, rats were treated by smudging for half an hour, twice a day (8:00 and 18:00);IH with pul-monary emphysema group, rats were treated by 30 s nitrogen and then 90 s air from 9:00-17:00 daily. After exposure four-teen weeks, rats were killed. qRT-PCR assay was conducted to detect the expression of HIF-1α mRNA, Bax mRNA and Bcl-2 mRNA in live tissues. Results The expressions of HIF-1αmRNA, Bax mRNA and Bax/Bcl-2 were significantly higher in IH with pulmonary emphysema group than those in control group,IH group and pulmonary emphysema group (P0.05). The levels of HIF-1αand Bax were positively correlated with the level of Bax/Bcl-2 (r=0.732 and 0.699),but the lev-els of HIF-1αand Bax were negatively correlated with the level of Bcl-2 (r=-0.705). Conclusion The expression levels of HIF-1αmRNA, Bax mRNA and Bcl-2 mRNA were over-regulated in hepatocytes induced by intermittent hypoxia with pul-monary emphysema. The HIF-1αexpression was correlated with Bax and Bcl-2, suggesting that HIF-1αmay promote the hepatocyte apoptosis through transcriptional co-activators, Bax and Bcl-2.