[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.
Zou
Xiao-yi
XY
Department of Neurology, West China Hospital, Sichuan University, Chengdu 610041, China.
Lai
Xiao-hui
XH
Shang
Hui-fang
HF
Zhou
Shu-shun
SS
Zeng
Xiao-rong
XR
Yang
Yan
Y
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