Intermittent hypoxia improves atrial tolerance to subsequent anoxia and reduces stress protein expression
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We tested the hypothesis that 21 days of intermittent hypoxia (IH) increases the tolerance of the spontaneously beating guinea‐pig double atria preparation to acute in‐vitro hypoxia, and reduces cardiac stress protein expression. A total of 28 guinea‐pigs were divided into four groups: (i) IH; (ii) IH + in‐vitro hypoxia (IH + IV); (iii) control (CON); (iv) control + in‐vitro hypoxia (CON + IV). The IH animals were exposed to 8% O 2 /0.3% CO 2 for 12 h day –1 for 21 days. Normoxic controls were exposed to room air for the same duration. Acute in‐vitro hypoxia (20, 10, 5 and 0% O 2 in 5% CO 2 ) was introduced into the atrial preparation. Heat shock protein (Hsp) 70 and Hsp90 content were determined by Western blotting. Intermittent hypoxia groups demonstrated typical responses to chronic hypoxic exposure, characterized by significantly ( P < 0.05) lower body weights, reduced growth rates and increased heart weight/body weight ratios. In the CON + IV group, in‐vitro hypoxia reduced heart rate (20% O 2 , –30 ± 8 beats min –1 ; 10% O 2 , –34 ± 8 beats min –1 ; 5% O 2 , –37 ± 9 beats min –1 and 0% O 2 , –51 ± 9* beats min –1 : * P < 0.05 vs. 20% O 2 ). At 0% O 2, the decrease in the rate response was significantly attenuated in the IH + IV (–30 ± 8 beats min –1 ; n =10) compared with the CON + IV (–51 ± 9 beats min –1 ; n =10). IH significantly reduced atrial Hsp70 and Hsp90 expression, however, levels of both proteins were unchanged in the ventricle. Furthermore, Hsp90 and to a lesser degree Hsp70 in the atria remained suppressed following in‐vitro hypoxia in the IH group. Our results show that the increased resistance of the isolated atria to anoxia following IH may contribute to the concomitant reductions in basal and hypoxia‐induced Hsp expression as the overall stress response is reduced.Keywords:
Hypoxia
Intermittent hypoxia
Room air distribution
Objective To establish a hypoxia amimal model with different exposed periods and severe intermittent hypoxia and to explore effects of severe intermittent hypoxia on learning and memory function in rats.Methods Male Wistar rats(n=48) were randomly divided into chronic intermittent hypoxia group and control group.The 5% hypoxia models was made with hypoxia box.AT 2,4,6,and 8 weeks after hypoxia,the morphologic changes of neuron were observed with HE staining.The learning and memory ability of the rats were assessed with Morris water maze.Results Compared with the control group,neuronal morphologic structure in the hypoxia group was damaged significantly.The survival neuronal density was decreased with prolonged hypoxia(13.18 ± 2.18).The mean of escaping latency period was 49.17±8.87,58.47±6.98,65.15±7.44,and 68.42±7.91 seconds at 2,4,6,and 8 weeks in intermittent hypoxia group,which was decreased with prolonged hypoxia(P0.5).Conclusion Intermittent hypoxia can cause nerve cell damage and learning-memory dysfunction.The damage increases with the prolonged intermittent hypoxia.
Hypoxia
Intermittent hypoxia
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HSP60
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Objective: To observe the expression of the rats gastrocnemius protective protein and heat shock protein 70 under the simulated hypoxia training at different altitudes,and provided hypoxia training of study foundation.Method: Sixty healthy adult male SD rats were randomly divided into six groups according to their body mass.Adopting the oxygen content of 14.5% and 12.7% hypoxia models of ‘living high-training low’,increase the exercise intensity gradually for 4 weeks.And after that,take the rat’s gastrocnemius to test the expression of HSP70 with RT-PCR and immunohistochemistry technologies.Results: The expression of HSP70 was all able to be inducted from normal training,hypoxia exposure and hypoxia training;compared with normal training,the expression of HSP70 of hypoxia training groups increased(P0.05)under the hypoxia condition,and the expression of Group LH14.5%O2 and Group Hilo12.7 %O2 increased significantly(P0.01).Conclusion: Hypoxia and training,or hypoxia training can increased the expression of HSP70,the impact of the stimulation of hypoxia training to the expression of HSP70 increased compared with hypoxia exposure.
Hypoxia
Gastrocnemius muscle
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Ventilatory instability, reflected by enhanced acute hypoxic (AHVR) and hypercapnic (AHCVR) ventilatory responses is a fundamental component of obstructive sleep apnoea (OSA) pathogenesis. Intermittent hypoxia-induced inflammation is postulated to promote AHVR enhancement in OSA, although the role of inflammation in intermittent hypoxia-induced respiratory changes in humans has not been examined. Thus, this study assessed the role of inflammation in intermittent hypoxia-induced respiratory plasticity in healthy humans. In a double-blind, placebo-controlled, randomised crossover study design, 12 males were exposed to 6 h of intermittent hypoxia on three occasions. Prior to intermittent hypoxia exposures, participants ingested (for 4 days) either placebo or the nonsteroidal anti-inflammatory drugs indomethacin (nonselective cyclooxygenase (COX) inhibitor) and celecoxib (selective COX-2 inhibitor). Pre- and post-intermittent hypoxia resting ventilation, AHVR, AHCVR and serum concentration of the pro-inflammatory cytokine tumour necrosis factor (TNF)-α were assessed. Pre-intermittent hypoxia resting ventilation, AHVR, AHCVR and TNF-α concentrations were similar across all three conditions (p≥0.093). Intermittent hypoxia increased resting ventilation and the AHVR similarly across all conditions (p=0.827), while the AHCVR was increased (p=0.003) and TNF-α was decreased (p=0.006) with only selective COX-2 inhibition. These findings indicate that inflammation does not contribute to human intermittent hypoxia-induced respiratory plasticity. Moreover, selective COX-2 inhibition augmented the AHCVR following intermittent hypoxia exposure, suggesting that selective COX-2 inhibition could exacerbate OSA severity by increasing ventilatory instability.
Intermittent hypoxia
Hypoxia
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Hsp27
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Abstract Heat shock proteins (Hsps) are a ubiquitous feature of cells in which these proteins cope with stress‐induced denaturation of other proteins. Among the different families of Hsps, the 70 kDa family ( hsp70 ) is the most highly conserved and has been most extensively studied. Apart from their primary role in cellular defense under stress condition, a number of studies in recent years have shown the immense potential of hsp70 in pollution monitoring using even transgenic approach both in vivo and in vitro. This article reviews the recent developments in the widespread application of hsp70 in environmental risk assessment. © 2003 Wiley Periodicals, Inc. J Biochem Mol Toxicol 17:249–254, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10086
Denaturation (fissile materials)
Environmental stress
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Hypoxia
Intermittent hypoxia
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Recently, IHT(intermittent hypoxia training)has been a highlight in the international academia of sports medicine.Hypoxia can be divided into two sorts in terms of the damage.One is dysoxia and the other is adapted cell hypoxia. Furthermore,IHT can also be defined as chronic hypoxia and intermittent hypoxia according to the training time .We introduce a variety of hypoxia training models and the hypoxia adaption of skeletal muscle and draw the conclusion that the cell signaling mechanisms in adaptions in IH is the future direction of research.
Intermittent hypoxia
Hypoxia
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HSP60
Brain ischemia
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Objective:To investigate the effect of heat shock protein 70(HSP70) expressions in neuronal cells with different hypoxia time.Methods:Cultured neuronal cells with different hypoxia time were divided into six groups(hypoxia 0h, 0.5h, 1h, 2h, 3h and 4h) after they have been infected with recombinant adenovirus(vAd-HSP70) for 48h.Cells in different groups were treated by hypoxia-reoxygenation, then the expression of HSP70 gene was examined by RT-PCR and Western blotting.Results:The expression of human HSP70 gene was tested in the vAd-HSP70-infected group.After hypoxia-reoxygenation treatment, expression of HSP70 mRNA and protein were at higher level within hypoxia 4h, reached its peak at hypoxia 1h, and then step down regularly.At hypoxia 4h group, the expression of HSP70 was lower than that of the other groups, with statistical significance(P0.05).Conclusions:The expression of HSP70 was at high level when the cultured neuronal cells were treated reoxygenation within hypoxia 2h and may also promote the functional recovery.
Hypoxia
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