慢性缺氧对化学感受的影响。
The influence of chronic hypoxia upon chemoreception.
作者信息
Powell Frank L
机构信息
Department of Medicine and White Mountain Research Station, University of California, San Diego, La Jolla, CA 92093-0623, USA.
出版信息
Respir Physiol Neurobiol. 2007 Jul 1;157(1):154-61. doi: 10.1016/j.resp.2007.01.009. Epub 2007 Jan 20.
Carotid body chemoreceptors are essential for time-dependent changes in ventilatory control during chronic hypoxia. Early theories of ventilatory acclimatization to hypoxia focused on time-dependent changes in known ventilatory stimuli, such as small changes in arterial pH that may play a significant role in some species. However, plasticity in the cellular and molecular mechanisms of carotid body chemoreception play a major role in ventilatory acclimatization to hypoxia in all species studied. Chronic hypoxia causes changes in (a) ion channels (potassium, sodium, calcium) to increase glomus cell excitability, and (b) neurotransmitters (dopamine, acetylcholine, ATP) and neuromodulators (endothelin-1) to increase carotid body afferent activity for a given PO(2) and optimize O(2)-sensitivity. O(2)-sensing heme-containing molecules in the carotid body have not been studied in chronic hypoxia. Plasticity in medullary respiratory centers processing carotid body afferent input also contributes to ventilatory acclimatization to hypoxia. It is not known if the same mechanisms occur in patients with chronic hypoxemia from lung disease or high altitude natives.
颈动脉体化学感受器对于慢性低氧期间通气控制的时间依赖性变化至关重要。早期关于低氧通气适应的理论集中在已知通气刺激的时间依赖性变化上，比如动脉pH的微小变化，这在某些物种中可能起重要作用。然而，在所有研究的物种中，颈动脉体化学感受的细胞和分子机制的可塑性在低氧通气适应中起主要作用。慢性低氧会导致以下变化：(a)离子通道（钾离子、钠离子、钙离子通道），以增加球细胞兴奋性；(b)神经递质（多巴胺、乙酰胆碱、三磷酸腺苷）和神经调质（内皮素-1），以在给定的氧分压下增加颈动脉体传入活动并优化氧敏感性。颈动脉体中含血红素的氧感应分子在慢性低氧中尚未得到研究。延髓呼吸中枢处理颈动脉体传入输入的可塑性也有助于低氧通气适应。尚不清楚患有肺部疾病导致慢性低氧血症的患者或高原原住民是否存在相同的机制。
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