Olubadewo J O, Rama Sastry B V
J Pharmacol Exp Ther. 1978 Feb;204(2):433-45.
Isolated villus from human term placenta contains about 167 nmol/g of acetylcholine (ACh). It was incubated in a muscle bath containing Krebs-Ringer bicarbonate buffer (pH 7.2-7.4) at 37 degrees C and ACh released into the medium was analyzed by pyrolysis-gas chromatography. The spontaneous release of ACh into the medium was linear with time and was 35 pmol/g/min. ACh was not released when Ca++ was absent in the medium. Raising the Ca++ concentration in the Krebs-Ringer bicarbonate buffer from 2.34 to 4.64 mM, or adding L-nicotine (58 muM) to the bath, increased the rate of release of ACh to 53 and 47 pmol/min respectively. Nicotine did not exhibit any effect on ACh release in the absence of Ca++ in the medium. Both the rate of the spontaneous release of ACh and the nicotine-induced increase in the release of ACh was decreased by atropine (152 muM). They were not influenced by d-tubocurarine (30 muM). Depolarizing concentrations of potassium (16-63 mM) in the medium increased the rate of release of ACh. Cocaine, a known Ca antagonist, decreased the rate of spontaneous release of ACh as well as nicotine-induced release of ACh. These observations indicate that 1) Ca++ ions in the external medium are required for release of ACh, 2) Ca++ ions in the external medium are required for release of ACh, 2) Ca++ ions act as a link between the stimulation of ACh release and the final release of ACh and 3) The effect of nicotine on placental release of ACh may be classified as a muscarinic type.
取自足月人胎盘的孤立绒毛含约167 nmol/g的乙酰胆碱（ACh）。将其置于含 Krebs - Ringer 碳酸氢盐缓冲液（pH 7.2 - 7.4）的肌肉浴中，于37℃孵育，通过热解气相色谱法分析释放到培养基中的 ACh。ACh 向培养基中的自发释放与时间呈线性关系，为35 pmol/g/分钟。当培养基中不存在 Ca++ 时，ACh 不释放。将 Krebs - Ringer 碳酸氢盐缓冲液中的 Ca++ 浓度从2.34 mM 提高到4.64 mM，或向浴中加入 L - 尼古丁（58 μM），分别使 ACh 的释放速率增加到53和47 pmol/分钟。在培养基中不存在 Ca++ 的情况下，尼古丁对 ACh 释放无任何影响。阿托品（152 μM）降低了 ACh 的自发释放速率以及尼古丁诱导的 ACh 释放增加。它们不受 d - 筒箭毒碱（30 μM）影响。培养基中去极化浓度的钾（16 - 63 mM）增加了 ACh 的释放速率。可卡因，一种已知的 Ca 拮抗剂，降低了 ACh 的自发释放速率以及尼古丁诱导的 ACh 释放。这些观察结果表明：1）外部培养基中的 Ca++ 离子是 ACh 释放所必需的；2）外部培养基中的 Ca++ 离子是 ACh 释放所必需的；3）Ca++ 离子充当 ACh 释放刺激与 ACh 最终释放之间的联系；4）尼古丁对胎盘 ACh 释放的作用可能属于毒蕈碱型。
