Jones S V
Department of Psychiatry, University of Vermont College of Medicine, Burlington 05405.
Neurosci Lett. 1992 Dec 7;147(2):125-30. doi: 10.1016/0304-3940(92)90576-s.
The modulation of an inwardly rectifying potassium conductance by muscarinic receptor stimulation was studied in the AtT-20 pituitary cell line, using the whole-cell patch-clamp technique. Only m4 mRNA was detected in these cells, thus, it is assumed that the actions of muscarinic receptor stimulation are mediated by the m4 receptor. AtT-20 cells express a slowly activating inwardly rectifying potassium conductance. Application of acetylcholine (ACh), resulted in an atropine sensitive, reversible increase in inwardly rectifying current. The ACh-induced current differed from the current recorded in control, in that it was fast activating, while the control current was slowly activating. Inclusion of GTP gamma S in the patch pipette activated an inward current with characteristics similar to the ACh-induced current, and the ACh-induced current response could be inhibited by pre-incubation with pertussis toxin (PTX). It is concluded that the m4 muscarinic receptor is coupled to an inwardly rectifying potassium conductance via a PTX sensitive G-protein.
利用全细胞膜片钳技术，在AtT-20垂体细胞系中研究了毒蕈碱受体刺激对内向整流钾电导的调节作用。在这些细胞中仅检测到m4 mRNA，因此，推测毒蕈碱受体刺激的作用是由m4受体介导的。AtT-20细胞表达一种缓慢激活的内向整流钾电导。应用乙酰胆碱（ACh）可导致内向整流电流出现对阿托品敏感的、可逆的增加。ACh诱导的电流与对照记录的电流不同，在于它是快速激活的，而对照电流是缓慢激活的。在膜片吸管中加入GTPγS可激活一种具有与ACh诱导电流相似特征的内向电流，并且ACh诱导的电流反应可被百日咳毒素（PTX）预孵育所抑制。得出的结论是，m4毒蕈碱受体通过一种对PTX敏感的G蛋白与内向整流钾电导偶联。
