大鼠体内通气和单一化学敏感神经元对高碳酸血症反应的发展

C.E Stunden, J.A Filosa, A.J Garcia, J.B Dean, R.W Putnam
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引用次数: 136

摘要

我们使用压力容积描记术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 (e))随吸入CO2的增加而逐渐增加。V (e)的升高与潮气量的增加有关,而与呼吸速率无关。在所研究的所有动物中,二氧化碳敏感性(由V / e与吸入% CO2曲线的斜率确定)每天都是可变的。新生儿在出生后1天(P1)化疗敏感性较高,在第一周内下降至P8左右的最低水平。通过成年大鼠,P10的化学敏感性再次上升到更高的值。这些体内通气反应的发育模式与个体蓝斑(LC)神经元对二氧化碳增加的反应不同。采用脑切片穿孔贴片(两性霉素B)技术测定LC神经元膜电位(Vm)。在所有年龄的研究中,LC神经元对高碳酸性酸中毒(10% CO2, pH 7.0)的反应增加了约44%的放电率。因此,新生大鼠体内对高碳酸血症的通气反应与单个LC神经元对高碳酸血症酸中毒的Vm反应不相关。这些数据表明,大鼠对通气的CO2敏感性可能以两种形式存在,一种是高敏感性的新生儿(或胎儿)形式,另一种是低敏感性的成年形式,在这两种形式之间的过渡期间存在一个非常低敏感性的关键窗口(~ P8)。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Development of in vivo ventilatory and single chemosensitive neuron responses to hypercapnia in rats

We used pressure plethysmography to study breathing patterns of neonatal and adult rats acutely exposed to elevated levels of CO2. Ventilation (V̇e) increased progressively with increasing inspired CO2. The rise in V̇e 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 V̇e vs. inspired % CO2 curve) was variable on a day to day basis. Chemosensitivity was high in neonates 1 day after birth (P1) 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 (LC) neuron responses to increased CO2. The membrane potential (Vm) 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 ∼44% in response to hypercapnic acidosis (10% CO2, pH 7.0). Thus the in vivo ventilatory response to hypercapnia was not correlated with the Vm 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 (∼P8).

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