Acetylcholine modulates respiratory pattern: Effects mediated by M3-like receptors in preBotzinger complex inspiratory neurons
Acetylcholine modulates respiratory pattern: Effects mediated by M3-like receptors in preBotzinger complex inspiratory neurons
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DOI：
10.1152/jn.2000.83.3.1243
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发表时间：
2000-03-01
影响因子：
2.5
通讯作者：
Feldman, JL
中科院分区：
文献类型：
--
作者：
Shao, XM;Feldman, JL
脑干中胆碱能神经传递的扰动影响体内和体外的呼吸运动模式;潜在的细胞机制尚不清楚。使用髓片制备从新生大鼠自发产生呼吸节律，我们膜片钳吸气神经元的preBotzinger复杂（preBotC），假设网站的呼吸节律的产生，并同时记录与运动相关的运动输出从舌下神经（XIIn）。大多数（88%）的吸气神经元测试响应于乙酰胆碱（ACh）或氨甲酰胆碱（CCh）或局部应用浴应用毒蕈碱。浴应用50亩M毒蕈碱增加的频率，幅度和持续时间的XIIn吸气爆发。在细胞水平，毒蕈碱诱导紧张性内向电流，增加的持续时间，并降低在电压钳下记录的preBotC吸气神经元的相位吸气内向电流的幅度。毒蕈碱还诱导在XIIn活性的呼气期明显的呼吸样活性;这些作用被阿托品阻断。在河豚毒素（TTX）存在的情况下，将2 mM的CCh或ACh局部喷射到preBotC吸气神经元上，在电压钳下诱导一个内向电流沿着膜电导的增加，在电流钳下诱导一个去极化。阿托品以浓度依赖性方式阻断这种反应。浴应用1 μ M哌仑西平，10 μ M的gallamine，或10 μ M的himbacine对CCH诱导的电流几乎没有影响，而10 μ M的4-二苯基乙酰氧基-N-甲基哌啶methiodide阻断电流。在-110~-20 mV范围内呈线性关系，在-11.4 mV时呈反向关系。在起搏和非起搏吸气神经元中发现了类似的反应。当贴片电极含有高浓度的EGTA（11 mM）或双-（邻氨基苯氧基）-N，N，N'，N'-四乙酸（10 mM）时，对CCh的响应不受影响。用128mMTris-Cl代替NaCl后，对CCh的响应大大降低，I-V曲线左移，反转电位移至-47mV。将细胞外Cl-浓度从140 mM降低至70 mM对逆转电位没有影响。这些结果表明，在preBotC吸气神经元中，ACh作用于突触后神经元上的M3-样ACh受体，以打开对Na+和K+可渗透的通道，而不是Ca 2+依赖性的。这种内向阳离子电流在去极化preBotC吸气神经元（包括起搏器）中起着重要作用，这可能是在系统/行为水平上观察到的呼吸运动输出频率增加的乙酰胆碱诱导的原因。
Perturbations of cholinergic neurotransmission in the brain stem affect respiratory motor pattern both in vivo and in vitro; the underlying cellular mechanisms are unclear. Using a medullary slice preparation from neonatal rat that spontaneously generates respiratory rhythm, we patch-clamped inspiratory neurons in the preBotzinger complex (preBotC), the hypothesized site for respiratory rhythm generation, and simultaneously recorded respiratory-related motor output from the hypoglossal nerve (XIIn). Most (88%) of the inspiratory neurons tested responded to local application of acetylcholine (ACh) or carbachol (CCh) or bath application of muscarine. Bath application of 50 mu M muscarine increased the frequency, amplitude, and duration of XIIn inspiratory bursts. At the cellular level, muscarine induced a tonic inward current, increased the duration, and decreased the amplitude of the phasic inspiratory inward currents in preBotC inspiratory neurons recorded under voltage clamp at -60 mV. Muscarine also induced seizure-like activity evident during expiratory periods in XIIn activity; these effects were blocked by atropine. In the presence of tetrodotoxin (TTX), local ejection of 2 mM CCh or ACh onto preBotC inspiratory neurons induced an inward current along with an increase in membrane conductance under voltage clamp and induced a depolarization under current clamp. This response was blocked by atropine in a concentration-dependent manner. Bath application of 1 mu M pirenzepine, 10 mu M gallamine, or 10 mu M himbacine had little effect on the CCh-induced current, whereas 10 mu M 4-diphenylacetoxy-N-methylpiperidine methiodide blocked the current. The current-voltage (I-V) relationship of the CCh-induced response was linear in the range of -110 to -20 mV and reversed at -11.4 mV. Similar responses were found in both pacemaker and nonpacemaker inspiratory neurons. The response to CCh was unaffected when patch electrodes contained a high concentration of EGTA (11 mM) or bis-(o-aminophenoxy)-N,N,N',N'-tetraacetic acid (10 mM). The response to CCh was reduced greatly by substitution of 128 mM Tris-Cl for NaCl in the bath solution; the I-V curve shifted to the left and the reversal potential shifted to -47 mV. Lowering extracellular Cl- concentration from 140 to 70 mM had no effect on the reversal potential. These results suggest that in preBotC inspiratory neurons, ACh acts on M3-like ACh receptors on the postsynaptic neurons to open a channel permeable to Na+ and K+ that is not Ca2+ dependent. This inward cation current plays a major role in depolarizing preBotC inspiratory neurons, including pacemakers, that may account for the ACh-induced increase in the frequency of respiratory motor output observed at the systems/behavioral level.