Newton M W, Jenden D J
J Pharmacol Exp Ther. 1985 Oct;235(1):135-46.
The metabolism and subcellular distribution of a novel choline analog, N-amino-N,N-dimethylaminoethanol (N-aminodeanol) in rat striatal synaptosomes was studied using combined gas chromatography mass spectrometry for simultaneous estimation of N-aminodeanol, choline, tracer choline and their acetate esters. The enzymes choline acetyltransferase, acetylcholinesterase and choline kinase were assayed in kinetic studies using N-aminodeanol or acetyl-N-aminodeanol as substrates. The results demonstrate that [2H4]N-aminodeanol is transported and acetylated in synaptosomes at rates approximately 30% of those measured for [2H4]choline. Of the [2H4]N-aminodeanol that was transported by the high affinity choline uptake system, the proportion acetylated was similar to that measured for [2H4]choline. [2H4]Acetyl-N-aminodeanol replaced endogenous acetylcholine stores and was released. The combined release of endogenous and false transmitters from synaptosomes in the presence of [2H4]N-aminodeanol was reduced compared to controls in the presence of [2H4]choline, although combined tissue stores did not change significantly. After coincubation with [2H4]N-aminodeanol and [2H4]choline, the molar ratios of true and false transmitter in the tissue appeared to reflect the kinetic parameters for high affinity transport of the precursors. Subcellular fractionation experiments indicated that [2H4]acetyl-N-aminodeanol was incorporated into vesicles more slowly than [2H4]acetylcholine. These results indicate that the reduced rate of turnover in the presence of false precursor is not due to its rate of acetylation or to the rate of release of previously formed false transmitter, but rather to the slower membrane transport of N-aminodeanol by the high affinity uptake system. The replacement of endogenous acetylcholine in synaptosomes by acetyl-N-aminodeanol, which has 4% the potency of acetylcholine at muscarinic receptors, suggests that N-aminodeanol may be useful in studying the in vivo effects of a false cholinergic transmitter.
利用气相色谱 - 质谱联用技术同时测定新型胆碱类似物N - 氨基 - N,N - 二甲基氨基乙醇（N - 氨基乙醇）、胆碱、示踪胆碱及其乙酸酯，研究了其在大鼠纹状体突触体中的代谢和亚细胞分布。在动力学研究中，以N - 氨基乙醇或乙酰 - N - 氨基乙醇为底物，测定了胆碱乙酰转移酶、乙酰胆碱酯酶和胆碱激酶的活性。结果表明，[2H4]N - 氨基乙醇在突触体中的转运和乙酰化速率约为[2H4]胆碱的30%。在通过高亲和力胆碱摄取系统转运的[2H4]N - 氨基乙醇中，乙酰化比例与[2H4]胆碱的测定值相似。[2H4]乙酰 - N - 氨基乙醇替代了内源性乙酰胆碱储备并被释放。与存在[2H4]胆碱的对照组相比，在存在[2H4]N - 氨基乙醇时，突触体中内源性和假性递质的联合释放减少，尽管组织中的联合储备没有显著变化。与[2H4]N - 氨基乙醇和[2H4]胆碱共同孵育后，组织中真性和假性递质的摩尔比似乎反映了前体高亲和力转运的动力学参数。亚细胞分级分离实验表明，[2H4]乙酰 - N - 氨基乙醇比[2H4]乙酰胆碱更慢地掺入囊泡中。这些结果表明，在存在假性前体时周转率降低不是由于其乙酰化速率或先前形成的假性递质的释放速率，而是由于高亲和力摄取系统对N - 氨基乙醇的膜转运较慢。乙酰 - N - 氨基乙醇在毒蕈碱受体上的效力仅为乙酰胆碱的4%，它在突触体中替代内源性乙酰胆碱，这表明N - 氨基乙醇可能有助于研究假性胆碱能递质的体内效应。
