Episodic but not continuous hypoxia elicits long-term facilitation of phrenic motor output in rats
Episodic but not continuous hypoxia elicits long-term facilitation of phrenic motor output in rats
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DOI：
10.1111/j.1469-7793.2000.00215.x
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发表时间：
2000-11-15
影响因子：
5.5
通讯作者：
Mitchell, GS
中科院分区：
文献类型：
--
作者：
Baker, TL;Mitchell, GS
1.间歇性低氧诱发麻醉大鼠膈神经运动输出的长时程易化。我们检验了一个假设，即连续缺氧的累积时间相等不会引起膈LTF。在麻醉、切断迷走神经、麻痹和通气的大鼠中记录了综合膈神经活动，大鼠暴露于：（1）3 × 3分钟缺氧事件（吸入的O-2分数（F-I，F-O2）= 0.11）通过5分钟高氧分离（F-I，F-O_2 = 0.5; n = 6），（2）9 min连续缺氧（n = 6），或（3）20 min连续缺氧（n = 7）。在整个方案中维持等碳酸血症。与先前的研究一致，间歇性缺氧后膈神经振幅显著升高至少1小时（缺氧后60分钟为78 +/- 15%; P < 0.05），伴随着爆发频率的增加（11 +/- 2.1次爆发/分钟; P < 0.05）。相比之下，持续缺氧9或20 min并没有引起膈振幅（缺氧60 min后分别为4.7 +/- 5.1和10.1 +/- 10.2%; P > 0.05）或频率（缺氧60 min后分别为4.6 +/- 1.3和5.1 +/- 2爆发min（-1）; P > 0.05）的LTF.结果表明，低氧诱导的膈运动输出的长时程易化对麻醉大鼠的低氧暴露模式敏感。
1. Intermittent hypoxia elicits long-term facilitation (LTF) of phrenic motor output in anaesthetized rats. We tested the hypothesis that an equal cumulative duration of continuous hypoxia would not elicit phrenic LTF.2. Integrated phrenic nerve activity was recorded in urethane-anaesthetized, vagotomized, paralysed and ventilated rats exposed to: (1) 3 x 3 min hypoxic episodes (inspired O-2 fraction (F-I,F-O2)= 0.11) separated by 5 min hyperoxia (F-I,F-O2 = 0.5; n = 6), (2) 9 min continuous hypoxia (n = 6), or (3) 20 min continuous hypoxia (n = 7). Isocapnia was maintained throughout the protocol.3. Consistent with previous studies, phrenic amplitude was significantly elevated for at least 1 h following intermittent hypoxia (78 +/- 15% 60 min post-hypoxia; P < 0.05) with an associated increase in burst frequency (11 +/- 2.1 bursts min(-1); P < 0.05). In contrast, 9 or 20 min continuous hypoxia did not elicit LTF of either phrenic amplitude (4.7 +/- 5.1 and 10.1 +/- 10.2% 60 min post-hypoxia, respectively; P > 0.05) or frequency (4.6 +/- 1.3 and 5.1 +/- 2 bursts min(-1) 60 min post-hypoxia, respectively; P > 0.05).4. The results indicate that hypoxia-induced long-term facilitation of phrenic motor output is sensitive to the pattern of hypoxic exposure in anaesthetized rats.