Sastry B V, Olubadewo J O, Boehm F H
Arch Int Pharmacodyn Ther. 1977 Sep;229(1):23-36.
According to our studies, human term placenta contains about 112 nmol/g of ACh. In the present studies, isolated placental villi were suspended in Kreb's bicarbonate buffer (pH 7.4) at 37 degrees and acetylcholine (ACh) released into the medium was analyzed by gas chromatography. The spontaneous release of ACh into the medium was linear with time and was 35 pmol/g/min. Cocaine in doses of 280 and 56o micrometer decreased the spontaneous release of ACh to 23, and 17 pmol/g/min, respectively. Raising the Ca2+ concentration in the Kreb's bicarbonate buffer from 2.34 to 4.64 mM, or the addition of nicotine (58 micrometer) to the bath increased the rate of release of ACh to 53 and 47 pmol/g/min, respectively. Cocaine decreased the rate of release of ACh even in the presence of Ca2+ or nicotine. ACh was not released when Ca2+ was absent in the medium. Nicotine did not stimulate the release of ACh in the Ca2+ free medium. High concentrations of K+ increased ACh release in the presence of Ca2+ and it did not have any effect on ACh release in the absence of Ca2+. These observations indicate that external Ca2+ is required for the release of ACh and cocaine acts possibly by preventing the entry of external Ca2+ into the syncytiotrophoblast, and thereby decreases ACh release from the placental villus.
根据我们的研究，足月人胎盘含约112 nmol/g的乙酰胆碱（ACh）。在本研究中，将分离的胎盘绒毛在37℃下悬浮于pH 7.4的克雷布斯碳酸氢盐缓冲液中，采用气相色谱法分析释放到培养基中的乙酰胆碱（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。剂量为280和560微摩尔的可卡因分别将ACh的自发释放降低至23和17 pmol/g/分钟。将克雷布斯碳酸氢盐缓冲液中的Ca2+浓度从2.34 mM提高到4.64 mM，或向浴液中添加尼古丁（58微摩尔），分别使ACh的释放速率增加至53和47 pmol/g/分钟。即使在存在Ca2+或尼古丁的情况下，可卡因也会降低ACh的释放速率。当培养基中不存在Ca2+时，ACh不会释放。尼古丁在无Ca2+的培养基中不会刺激ACh的释放。高浓度的K+在有Ca2+存在时会增加ACh的释放，而在无Ca2+时对ACh的释放没有任何影响。这些观察结果表明，ACh的释放需要细胞外Ca2+，可卡因可能通过阻止细胞外Ca2+进入合体滋养层，从而减少胎盘绒毛中ACh的释放。
