Respiration-modulated membrane potential and chemosensitivity of locus coeruleus neurones in the in vitro brainstem-spinal cord of the neonatal rat
Respiration-modulated membrane potential and chemosensitivity of locus coeruleus neurones in the in vitro brainstem-spinal cord of the neonatal rat
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DOI：
10.1111/j.1469-7793.1998.381bb.x
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发表时间：
1998-12-01
影响因子：
5.5
通讯作者：
Scheid, P
中科院分区：
文献类型：
--
作者：
Oyamada, Y;Ballantyne, D;Scheid, P
1. 采用全细胞（常规和双性霉素b穿孔补片）记录法检测蓝斑（LC）神经元（n=126）的活性，并在不同CO2浓度（2和8%；浴液pH 7.8和7.2）下测定新生大鼠（1-5日龄）体外脑干-脊髓制备中C4或C5膈神经根记录的LC活性与呼吸放电的关系。在大多数神经元（n=105）中，持续活动随呼吸频率而调节。通常，这包括一个去极化阶段和与膈破裂同步的放电频率增加，随后是一个超极化阶段和放电抑制（n=94 / 105）。呼吸调节的发生率从P1的91%下降到P5.3的57%。非NMDA受体拮抗剂6-氰-7-硝基喹啉-2,3-二酮（CNQX; 5 μ M）或NMDA受体拮抗剂dl -2-氨基-5-磷酸戊酸（APV; 100 μ M）的盆浴应用可消除这两个阶段的呼吸调节。肾上腺素能受体拮抗剂咪唑嗪（5 μ M）或酚妥拉明（0.8 μ M）可消除超极化相。这些结果表明，兴奋性氨基酸途径既参与兴奋性成分的传递，也参与抑制成分的传递，后者还涉及α(2)-肾上腺素受体介导的途径。将CO2浓度从2%增加到8%，导致呼气持续时间缩短，呼吸相抑制减弱或丧失；这伴随着去极化，放电频率增加，并且在最初存在它们的神经元中（60%），阈下膜电位振荡频率增加。在河豚毒素（TTX, 0.2 ~ 1.0 μ M）存在下，去极化反应保持不变。这些结果表明，在新生儿准备过程中，LC神经元构成了突触连接的脑干呼吸网络的一部分，并且LC构成了二氧化碳或ph依赖性化学接受的一个位点。
1. The activity of locus coeruleus (LC) neurones (n=126) was examined in whole-cell (conventional and amphotericin B-perforated patch) recordings, and the relationship of this activity to the respiratory discharge recorded on the C4 or C5 phrenic nerve roots was determined at different CO2 concentrations (2 and 8%; bath pH 7.8 and 7.2) in the in vitro brainstem-spinal cord preparation of the neonatal rat (1-5 days old).2. In most neurones (n=105) ongoing activity was modulated at respiratory frequency. Typically, this consisted of a phase of depolarization and increased discharge frequency synchronous with the phrenic burst, followed by a phase of hyperpolarization and inhibition of discharge (n=94 of 105). The incidence of respiratory modulation decreased from 91% on P1 to 57% on P5.3. Bath application of the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; 5 mu M) or the NMDA receptor antagonist DL-2-amino-5-phosphonovaleric acid (APV; 100 mu M) abolished both phases of respiratory modulation. The hyperpolarizing phase alone was abolished by the adrenoceptor antagonists idazoxan (5 mu M) or phentolamine (0.8 mu M). These results indicate that excitatory amino acid pathways are involved in the transmission of both the excitatory and inhibitory components and that the latter involves in addition an alpha(2)-adrenoceptor-mediated pathway.4. Increasing the CO2 concentration from 2 to 8% resulted in a shortening of expiratory duration and weakening or loss of respiratory-phased inhibition; this was accompanied by depolarization, increased discharge frequency and, in those neurones where they were initially present (60%), an increase in the frequency of subthreshold membrane potential oscillations. The depolarizing response was retained in the presence of tetrodotoxin (TTX, 0.2-1.0 mu M).5. These results indicate that in this neonatal preparation LC neurones form part of the synaptically connected brainstem respiratory network, aad that the LC constitutes a site of CO2- or pH-dependent chemoreception.