Control of breathing in vertebrates: effects of chronic respiratory challenges and modulation of discontinuous breathing

这项研究探讨了一些控制无尾两栖动物（青蛙和蟾蜍）呼吸的机制。与人类和其他哺乳动物不同，两栖动物不能连续呼吸。相反，它们表现出一种不连续的呼吸模式，称为周期性呼吸。这种类型的呼吸可以采取不规则的单次呼吸的形式，偶尔出现成对呼吸或将呼吸分组（通常为4-8次）成离散的发作，由称为呼吸暂停的无呼吸期分开（可以持续几分钟）。虽然周期性呼吸在两栖动物中是正常的，但在人类中却是不正常的和病态的。人类在睡眠中表现出这种呼吸模式，要么是由于气道阻塞（阻塞性睡眠呼吸暂停），要么是由于大脑中调节连续呼吸的区域异常（中枢性睡眠呼吸暂停）。人类睡眠呼吸暂停的任何一种形式都与心脏病发作或中风等心血管疾病的风险增加有关。此外，由于缺乏连续呼吸，呼吸暂停与血液中氧气水平的降低和血液中二氧化碳水平的增加有关。一般来说，氧气水平的降低被称为缺氧，而二氧化碳水平的增加被称为高碳酸血症。

This research examines some of the mechanisms involved in controlling breathing in anuran amphibians (frogs and toads). Unlike humans and other mammals, amphibians do not breathe continuously. Rather they display a discontinuous pattern of breathing called periodic breathing. This type of breathing can take the form of irregular single breaths, the occasional occurrence of pairs of breaths or the grouping of breaths (usually 4-8) into discrete episodes separated by periods of no breathing called apneas (which can be several minutes in length). While periodic breathing is normal in amphibians, it is abnormal and pathological in humans. Humans can display this pattern of breathing during sleep either due to an obstruction of the airway (obstructive sleep apnoea) or due to abnormalities in the areas of the brain that regulate continuous breathing (central sleep apnoea). Either form of sleep apnoea in humans is associated with increased risk for cardiovascular disease such as heart attack or stroke. Furthermore, apnoea is associated with a reduction in oxygen levels in the blood and an increase in carbon dioxide levels in the blood due to the absence of continuous breathing. In general, a reduction in oxygen levels is called hypoxia while an increase in carbon dioxide levels is called hypercapnia.