Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020440 (hypercapnia)
 7,939 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Muscular dystrophy is associated with inflammation and fiber necrosis in the diaphragm that may alter ventilatory function. The purpose of this study was to determine to what extent in vivo ventilatory function in dystrophic (mdx) mice was compromised and to assess the impact of deletion of tumor necrosis factor-alpha (TNF-alpha), a known proinflammatory cytokine, on ventilatory function, diaphragm contractility, and myosin heavy chain (MHC) distribution in 10-12-month-old mdx mice. Although the resting ventilatory pattern did not significantly differ between control and mdx mice, the ventilatory response to hypercapnia in mdx mice was significantly attenuated. Elimination of TNF-alpha significantly improved the hypercapnic ventilatory response and diaphragm muscle maximal isometric force. Long-term TNF-alpha deletion also altered the myosin heavy chain isoform profile of the diaphragm. These data indicate that a blunted ventilatory response to hypercapnia exists in mdx mice, and that TNF-alpha influences the progressive deterioration of diaphragm muscle in mdx mice.
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PMID:Ventilatory dysfunction in mdx mice: impact of tumor necrosis factor-alpha deletion. 1292 94

Obstructive sleep apnoea syndrome (OSAS) is a common respiratory disorder characterized by chronic intermittent hypoxia (CIH). We have shown that CIH causes upper airway muscle dysfunction in the rat due to oxidative stress. Ageing is an independent risk factor for the development of OSAS perhaps due to respiratory muscle remodelling and increased susceptibility to hypoxia. We sought to examine the effects of CIH on breathing and pharyngeal dilator muscle structure and function in aged rats. Aged (18-20 months), male Wistar rats were exposed to alternating cycles of normoxia and hypoxia (90 s each; F(I)O(2)=5% O(2) at nadir) or sham treatment for 8h/day for 9 days. Following CIH exposure, breathing was assessed by whole-body plethysmography. In addition, sternohyoid muscle contractile and endurance properties were examined in vitro. Muscle fibre type and cross-sectional area, and the activity of key oxidative and glycolytic enzymes were determined. CIH had no effect on basal breathing or ventilatory responses to hypoxia or hypercapnia. CIH did not alter succinate dehydrogenase or glycerol phosphate dehydrogenase enzyme activities, myosin heavy chain fibre areal density or cross-sectional area. Sternohyoid muscle force and endurance were unaffected by CIH exposure. Since we have established that this CIH paradigm causes sternohyoid muscle weakness in adult male rats, we conclude that aged rats have decreased susceptibility to CIH-induced stress. We suggest that structural remodelling with improved hypoxic tolerance in upper airway muscles may partly compensate for impaired neural regulation of the upper airway and increased propensity for airway collapse in aged mammals.
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PMID:Respiratory control and sternohyoid muscle structure and function in aged male rats: decreased susceptibility to chronic intermittent hypoxia. 2212 88