Wilkerson Julia E R, Devinney Michael, Mitchell Gordon S
Department of Comparative Biosciences University of Wisconsin Madison, WI, 53706, USA; Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
Department of Comparative Biosciences University of Wisconsin Madison, WI, 53706, USA; Department of Anesthesiology, Duke University, Durham, NC, 27710, USA.
Respir Physiol Neurobiol. 2018 Oct;256:15-20. doi: 10.1016/j.resp.2017.10.005. Epub 2017 Oct 23.
Phrenic long-term facilitation (pLTF) is a form of serotonin-dependent respiratory motor plasticity induced by moderate acute intermittent hypoxia (AIH), but not by moderate acute sustained hypoxia (ASH) of similar cumulative duration. Thus, moderate AIH-induced pLTF is sensitive to the pattern of hypoxia. On the other hand, pLTF induced by severe AIH protocols is neither pattern sensitive nor serotonin dependent (it converts to an adenosine-dependent mechanism). Although moderate AIH also induces hypoglossal LTF (hLTF), no data are available concerning its sensitivity/insensitivity to the pattern of hypoxia. Since hLTF following moderate hypoxia is serotonin-dependent, we hypothesized that hLTF is pattern-sensitive, similar to serotonin-dependent pLTF. Integrated hypoglossal nerve activity was recorded in urethane-anesthetized, vagotomized, paralyzed, and ventilated rats exposed to isocapnic AIH (3, 5min episodes of 11% O) or ASH (a single 25min episode of 11% O). Similar to previous studies of pLTF, hypoglossal motor output was elevated for more than 1h following AIH (50±20%, p<0.01), but not ASH (-6±9%, p>0.05). Frequency LTF was not observed following either hypoxic exposure. Thus, in agreement with our hypothesis, hypoglossal LTF following moderate AIH is pattern-sensitive, similar to phrenic LTF.
膈神经长期易化（pLTF）是一种由中度急性间歇性低氧（AIH）诱导产生的、依赖于血清素的呼吸运动可塑性形式，但相似累积时长的中度急性持续性低氧（ASH）则不能诱导产生。因此，中度AIH诱导的pLTF对低氧模式敏感。另一方面，由重度AIH方案诱导的pLTF既不具有模式敏感性也不依赖于血清素（它转变为一种依赖于腺苷的机制）。虽然中度AIH也能诱导舌下神经长期易化（hLTF），但尚无关于其对低氧模式敏感/不敏感的数据。由于中度低氧后的hLTF依赖于血清素，我们推测hLTF具有模式敏感性，类似于依赖血清素的pLTF。在接受异碳酸血症性AIH（11%氧气，每次3或5分钟）或ASH（单次25分钟，11%氧气）的氨基甲酸乙酯麻醉、迷走神经切断、麻痹且通气的大鼠中记录舌下神经的综合活动。与先前关于pLTF的研究相似，AIH后舌下运动输出升高超过1小时（50±20%，p<0.01），但ASH后则没有（-6±9%，p>0.05）。两种低氧暴露后均未观察到频率长期易化。因此，与我们的假设一致，中度AIH后的舌下神经长期易化具有模式敏感性，类似于膈神经长期易化。
