Development of in vivo ventilatory and single chemosensitive neuron responses to hypercapnia in rats
Development of in vivo ventilatory and single chemosensitive neuron responses to hypercapnia in rats
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DOI：
10.1016/s0034-5687(01)00242-0
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发表时间：
2001-09-01
期刊：
影响因子：
--
通讯作者：
Putnam, RW
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文献类型：
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作者：
Stunden, CE;Filosa, JA;Putnam, RW
我们使用压力体积描记法来研究急性暴露于高水平CO2的新生大鼠和成年大鼠的呼吸模式。通气量（V/dotE）随着吸入CO2的增加而逐渐增加。V超过dotE的升高与潮气量的增加有关，但与呼吸频率无关。在研究的所有动物中，CO2敏感性（根据V/dotE与吸入% CO2曲线的斜率确定）每天都是可变的。新生儿出生后第一天（PI）的化疗敏感性较高，在第一周下降至约P8时的最低值。在P10至成年大鼠中，化学敏感性再次升高至略高的值。这些在体内的发育模式是不同的，比个人蓝斑（LQ神经元反应增加CO2。在脑片上使用穿孔贴片（apertericin B）技术测量LC神经元的膜电位（V-m）。在所有年龄段的研究，LC神经元增加了他们的放电率类似于44%，高碳酸酸中毒（10%CO2，pH 7.0）。因此，在体内的高碳酸血症的净化反应是不相关的V-M反应的个别LC神经元高碳酸血症的新生大鼠。这些数据表明，大鼠通气的CO2敏感性可能以两种形式存在，高敏感性新生儿（或胎儿）形式和较低敏感性成人形式，在两者之间的过渡期间（类似于P8）具有非常低敏感性的临界窗口。(C)2001 Elsevier Science B. V.保留所有权利。
We used pressure plethysmography to study breathing patterns of neonatal and adult rats acutely exposed to elevated levels of CO2. Ventilation (V over dotE) increased progressively with increasing inspired CO2. The rise in V over dotE was associated with an increase in tidal volume, but not respiratory rate. In all animals studied, the CO2 sensitivity (determined from the slope of the V over dotE vs. inspired % CO2 curve) was variable on a day to day basis. Chemosensitivity was high in neonates I day after birth (PI) and fell throughout the first week to a minimum at about P8. Chemosensitivity rose again to somewhat higher values in P10 through adult rats. The developmental pattern of these in vivo ventilatory responses was different than individual locus coeruleus (LQ neuron responses to increased CO2. The membrane potential (V-m) of LC neurons was measured using perforated patch (amphotericin B) techniques in brain slices. At all ages studied, LC neurons increased their firing rate by similar to 44% in response to hypercapnic acidosis (10% CO2, pH 7.0). Thus the in vivo ventilatory response to hypercapnia was not correlated with the V-m response of individual LC neurons to hypercapnic acidosis in neonatal rats. These data suggest that CO2 sensitivity of ventilation in rats may exist in two forms, a high-sensitivity neonatal (or fetal) form and a lower-sensitivity adult form, with a critical window of very low sensitivity during the period of transition between the two (similar to P8). (C) 2001 Elsevier Science B.V. All rights reserved.