Respiratory physiology & neurobiology
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Respir Physiol Neurobiol · Aug 2014
Clinical TrialExercise training improves breathing strategy and performance during the six-minute walk test in obese adolescents.
We aimed to examine ventilatory responses during the six-minute walk test in healthy-weight and obese adolescents before and after exercise training. ⋯ Our results suggest that exercise training can improve breathing strategy during submaximal exercise in obese adolescents and that this increase is associated with greater exercise performance.
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Respir Physiol Neurobiol · Aug 2014
Methylxanthine reversal of opioid-induced respiratory depression in the neonatal rat: mechanism and location of action.
Methylxanthines like caffeine and theophylline have long been used to treat apnea of prematurity. Despite their success in stimulating neonatal breathing, their mechanism of action remains poorly understood. ⋯ Here we used the in situ neonatal rat working heart-brainstem preparation and the ex vivo neonatal rat carotid body preparation to test the hypothesis that methylxanthines act at the level of the carotid body. We conclude that although the neonatal carotid body has active adenosine receptors, the effects of methylxanthine therapy are likely mediated centrally, predominantly via inhibition of cAMP-dependent phosphodiesterase-4.
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Respir Physiol Neurobiol · Aug 2014
Does expiratory muscle activity influence dynamic hyperinflation and exertional dyspnea in COPD?
Increased expiratory muscle activity is common during exercise in patients with COPD but its role in modulating operating lung volumes and dyspnea during incremental cycle ergometry is currently unknown. We compared gastric (Pga) and esophageal (Pes) pressures, operating lung volumes and qualitative descriptors of dyspnea during exercise in 12 COPD patients and 12 age- and sex-matched healthy controls. Pes- and Pga-derived measures of expiratory muscle activity were significantly (p<0.05) greater in COPD than in health during exercise. ⋯ Dynamic function of the diaphragm was not different in health and COPD throughout exercise. In both groups, dyspnea descriptors alluding to increased work and inspiratory difficulty predominated whereas expiratory difficulty was rarely reported, even at the limits of tolerance. In conclusion, increased expiratory muscle activity did not mitigate the rise in EELV, the relatively early respiratory mechanical constraints or the attendant perceived inspiratory difficulty during exercise in COPD.
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Respir Physiol Neurobiol · Aug 2014
Protective role of peroxisome proliferator-activated receptor β/δ in acute lung injury induced by prolonged hyperbaric hyperoxia in rats.
Peroxisome proliferator-activated receptor (PPAR)-β/δ is a transcription factor that belongs to the PPAR family, but the role of PPAR-β/δ in acute lung injury (ALI) induced by hyperbaric oxygen is unknown. In this study we investigated if PPAR-β/δ activation protects from hyperoxia-induced ALI in a rat model. ⋯ However, administration of the PPAR-β/δ antagonist GSK0660 abolished these protective effects. These findings indicate that activation of PPAR-β/δ ameliorates hyperoxia-induced ALI in rats by up-regulating antioxidant enzyme activity as well as suppressing inflammation and apoptosis.