Respiratory physiology & neurobiology
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Respir Physiol Neurobiol · Oct 2014
Rabbit model of chest wall rigidity induced by fentanyl and the effects of apomorphine.
A rabbit model for fentanyl-induced chest wall rigidity and the effect of apomorphine was evaluated. Eleven New Zealand adult rabbits were anesthetized and mechanically ventilated. An esophageal balloon catheter was used to estimate pleural pressure (P(pl)). ⋯ In 5 rabbits, C(cw) decreased significantly after fentanyl administration and apomorphine was able to restore C(cw) to baseline values. Rabbits can be used as a model for fentanyl-induced chest wall rigidity. Results from this study support central dopaminergic pathways as being at least partially responsible for the opioid-induced chest wall rigidity.
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Respir Physiol Neurobiol · Oct 2014
Spontaneous swallowing occurs during autoresuscitation in the in situ brainstem preparation of rat.
Previous studies report that upper airway reflexes are operational during autoresuscitation from respiratory arrest. We investigated swallowing/breathing interactions, measured by recording of vagal (VNA) and phrenic nerve activities (PNA), during autoresuscitation in the in situ perfused brainstem preparation of juvenile rats. During the initial surgery, respiratory arrest was induced by exsanguination and cooling. ⋯ Successful autoresuscitation was characterised by re-establishment of the 3 phase respiratory motor pattern and no spontaneous swallowing. Pharmacological inhibition (isoguvacine, 10 mM, 50-75 nl; n=10) of the Kölliker-Fuse nucleus (KF) mimicked stage 2 autoresuscitation. However, the frequency of spontaneous swallowing after KF inhibition did not correlate with subsequent recovery of the eupneic respiratory motor pattern.
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Respir Physiol Neurobiol · Sep 2014
Regional distribution of lung compliance by image analysis of computed tomograms.
Computed tomography (CT) can yield quantitative information about volume distribution in the lung. By combining information provided by CT and respiratory mechanics, this study aims at quantifying regional lung compliance (CL) and its distribution and homogeneity in mechanically ventilated pigs. The animals underwent inspiratory hold maneuvers at 12 lung volumes with simultaneous CT exposure at two end-expiratory pressure levels and before and after acute lung injury (ALI) by oleic acid administration. ⋯ A remarkably heterogeneous distribution of voxel compliance was found in the injured lungs. As the lung inflation increased, the homogeneity increased in healthy lungs but decreased in injured lungs. Image analysis brought novel findings regarding spatial homogeneity of compliance, which increases in ALI but not in healthy lungs by applying PEEP after a recruitment maneuver.
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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.