Provan S D, Miyamoto M D
Department of Pharmacology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City 37614.
Neurosci Lett. 1991 Feb 11;123(1):127-30. doi: 10.1016/0304-3940(91)90174-r.
The effect of 1,2,3,4-tetrahydro-9-aminoacridine (THA) on quantal transmitter release was examined at the frog neuromuscular junction. THA (3 microM) caused an increase in m (no. of quanta released) as measured by K(+)-evoked miniature endplate potential (MEPP) frequency. This was due to an increase in p (probability of release), as n (no. of functional release sites) was unchanged. The increase in p was dose-dependent over a range of 0.3-10 microM. By contrast, physostigmine (3 microM) caused a decrease in p, and neostigmine, which does not cross the nerve membrane, had no consistent effect on p. At the postsynaptic site, neostigmine produced the largest increase in MEPP size (79.2%), and THA produced the smallest (17.5%). The divergent effects of THA and physostigmine on p indicate a fundamental difference in their actions at the nerve terminal.
在青蛙神经肌肉接头处研究了1,2,3,4-四氢-9-氨基吖啶（THA）对量子递质释放的影响。通过钾离子诱发的微小终板电位（MEPP）频率测量，THA（3微摩尔）使m（释放的量子数）增加。这是由于p（释放概率）增加，而n（功能性释放位点的数量）未改变。在0.3 - 10微摩尔范围内，p的增加呈剂量依赖性。相比之下，毒扁豆碱（3微摩尔）使p降低，而不能穿过神经膜的新斯的明对p没有一致的影响。在突触后位点，新斯的明使MEPP大小增加最多（79.2%），而THA增加最少（17.5%）。THA和毒扁豆碱对p的不同影响表明它们在神经末梢的作用存在根本差异。
