Scemes E, Garcia Mendes E
Comp Biochem Physiol C Comp Pharmacol Toxicol. 1986;83(1):171-8. doi: 10.1016/0742-8413(86)90032-0.
Crude whole body homogenates of Liriope tetraphylla exhibit a cholinesterase particularly active on acetylthiocholine but not on butyrylthiocholine. The acetylthiocholine hydrolysis is completely blocked by neostigmine. The Michaelis-Menten constant for acetylthiocholine is 0.14 mM. The pharmacological analysis of the responses to the choline esters nicotine and atropine suggests the involvement in Liriope tetraphylla of a cholinergic mechanism in the pointing reflex. Butyrylcholine, nicotine and atropine (but not muscarinic agonists) caused the contraction of the subumbrellar radial muscles. The effects of atropine were dose-dependent and were depressed in competition with muscarinic agonists. MgCl2 interfered with the action of atropine. The results were explained by suggesting the existence, at least at the neuromuscular junction, of excitatory (nicotinic) and inhibitory (muscarinic) pre-synaptic receptors modulating the release of the (unknown) transmitter acting post-synaptically.
麦冬的粗制全身匀浆表现出一种对乙酰硫代胆碱特别活跃但对丁酰硫代胆碱不活跃的胆碱酯酶。乙酰硫代胆碱的水解被新斯的明完全阻断。乙酰硫代胆碱的米氏常数为0.14 mM。对胆碱酯类尼古丁和阿托品反应的药理学分析表明，麦冬在指向反射中存在胆碱能机制。丁酰胆碱、尼古丁和阿托品（但不是毒蕈碱激动剂）引起伞下放射状肌肉收缩。阿托品的作用呈剂量依赖性，并在与毒蕈碱激动剂竞争时受到抑制。MgCl2干扰了阿托品的作用。通过提示至少在神经肌肉接头处存在调节突触后作用的（未知）递质释放的兴奋性（烟碱样）和抑制性（毒蕈碱样）突触前受体来解释这些结果。
