[Effect of coriaria lactone on the activation of Ca(2+)-activated K+ channel in hippocampal pyrimidal neurons of rats].
OBJECTIVE
This research sought to disclose the regulatory effect of Coriaria lactone (CL) on the Ca(2+)-activated K+ channel in hippocampal pyrimidal neurons of Wistar rats in epileptogenesis.


METHODS
Cell-attached and inside-out methods of patch clamp technique were used to record the activity of single channel. The sample data were stored in a computer and analyzed by the application of Pclamp softwares.


RESULTS
1. By means of inside-out method, the KCa channels (120.34 +/- 25.12) pS on the membrane of hippocampal pyrimidal neurons showed a distinct dependence on calcium concentration (n = 6) and on voltage (n = 17), and the channels could be blocked by TEA. 2. With the use of cell-attached method, the KCa channels could be activated by CL apparently (n = 25, P < 0.01). 3. In the conditions where the neuronal membranous voltage was kept at 20 mV and the [Ca2+]i at 10(-8) mol/L in bath solution, the CL at concentrations from 0 microliter/ml to 1.0 microliter/ml could make the open state probability of KCa to increase from 0.025 to 0.553 (P < 0.01), the mean opening time (ms) to prolong from 1.875 +/- 0.412 to 6.829 +/- 0.136, and the mean closing time (ms) to decrease from 179.342 +/- 13.831 to 6.412 +/- 1.383 (n = 25, P < 0.01).


CONCLUSIONS
The membranous KCa activation induced by CL may play an important negative feedback regulating role in the mechanism of epileptogenesis.
Department of Neurology, West China Hospital, Sichuan University, Chengdu 610041, China.
Xiao-yi
XY
Zou
Xiao-hui
XH
Lai
Hui-fang
HF
Shang
Shu-shun
SS
Zhou
Xiao-rong
XR
Zeng
Yan
Y
Yang
D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D004827:Epilepsy / Q000139:chemically induced; D005260:Female; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism*; D007783:Lactones / Q000494:pharmacology*; D008297:Male; D008564:Membrane Potentials; D018408:Patch-Clamp Techniques; D024681:Potassium Channels, Calcium-Activated / Q000187:drug effects*; D017966:Pyramidal Cells / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D007783:Lactones; D024681:Potassium Channels, Calcium-Activated; C049836:coriaria lactone