Ballanyi K, Schlue W R
Institut für Zoologie, Universität Düsseldorf, Federal Republic of Germany.
Glia. 1989;2(5):330-45. doi: 10.1002/glia.440020506.
Ion-selective double-barrelled microelectrodes were used to measure the activities of intracellular K+, Na+, Cl-, and H+ (aiK, aiNa, aiCl, pHi) and membrane potential (Em) in neuropile glial cells as well as extracellular K+ activity (aeK) in the neuropile of the leech, Hirudo medicinalis, during bath application of carbachol. As measured with conventional single-barrelled microelectrodes, acetylcholine (ACh), nicotine, carbachol, tetramethylammonium (TMA), and choline elicited concentration-dependent (10(-6)-5 X 10(-3) M) transient membrane depolarizations of up to 60 mV amplitude whereas muscarine (10(-6)-10(-3) M) did not affect Em. alpha-Bungarotoxin (10(-7) M), decamethonium (10(-5) M), d-tubocurarine (5 X 10(-5) M), and strychnine (5 X 10(-5) M) blocked the carbachol depolarization by about 90%. Atropine (5 X 10(-5) M) blocked the response by about 75%, whereas hexamethonium was only effective at millimolar concentrations. Average baseline levels of aeK in the neuropile and of aiK, aiNa, and aiCl in the neuropile glial cells were about 3, 70, 10, and 7 mM, respectively. During the carbachol depolarization aeK and aiNa transiently increased, whereas aiK decreased. In contrast, a rise of aiK and a fall of aiNa were observed during glial depolarizations in solutions with elevated K+ concentration. aiCl increased during both the carbachol- and the K+-induced depolarization. During carbachol, pHi transiently fell by about 0.2 units from its average baseline level of 6.9, whereas an alkalinization of small amplitude was observed in high-K+ solutions. Bath-applied choline, TMA, and decamethonium rapidly accumulated in the neuropile glial cells as intracellularly monitored with double-barrelled microelectrodes filled with Corning K+ exchanger resin, which is highly selective for these agents. The results suggest that leech neuropile glial cells have a nicotinic ACh receptor coupled to a cation channel. It is hypothesized that this channel might also be permeable to choline, TMA, and decamethonium.
使用离子选择性双管微电极来测量医用蛭类（Hirudo medicinalis）神经纤维网神经胶质细胞内的钾离子（aiK）、钠离子（aiNa）、氯离子（aiCl）和氢离子（pHi）活性以及膜电位（Em），同时测量在浴槽中施加卡巴胆碱期间神经纤维网中的细胞外钾离子活性（aeK）。如用传统单管微电极所测量的那样，乙酰胆碱（ACh）、尼古丁、卡巴胆碱、四甲基铵（TMA）和胆碱引发浓度依赖性（10⁻⁶ - 5×10⁻³ M）的瞬时膜去极化，幅度高达60 mV，而毒蕈碱（10⁻⁶ - 10⁻³ M）不影响Em。α-银环蛇毒素（10⁻⁷ M）、十烃季铵（10⁻⁵ M）、d-筒箭毒碱（5×10⁻⁵ M）和士的宁（5×10⁻⁵ M）使卡巴胆碱去极化作用阻断约90%。阿托品（5×10⁻⁵ M）使反应阻断约75%，而六甲铵仅在毫摩尔浓度时有效。神经纤维网中aeK以及神经纤维网神经胶质细胞中aiK、aiNa和aiCl 的平均基线水平分别约为3 mM、70 mM、10 mM和7 mM。在卡巴胆碱去极化期间，aeK和aiNa瞬时增加，而aiK减少。相反，在钾离子浓度升高的溶液中神经胶质细胞去极化期间观察到aiK升高和aiNa下降。在卡巴胆碱和钾离子诱导的去极化过程中aiCl均增加。在卡巴胆碱作用期间，pHi从其平均基线水平6.9瞬时下降约0.2个单位，而在高钾溶液中观察到小幅度的碱化。用填充有对这些试剂具有高度选择性的康宁钾离子交换树脂的双管微电极在细胞内监测发现，浴槽中施加的胆碱、TMA和十烃季铵迅速在神经纤维网神经胶质细胞中积累。结果表明，水蛭神经纤维网神经胶质细胞具有与阳离子通道偶联的烟碱型ACh受体。据推测，该通道可能也对胆碱、TMA和十烃季铵通透。
