[Effects of melatonin on the voltage-gated delayed rectifier potassium channels of cultured hippocampal neurons of new-born rats].
OBJECTIVE
To investigate the effects of melatonin on voltage-gated delayed rectifier potassium channels.


METHODS
Hippocampus neurons were obtained from newborn Wistar rat and cultured. Primary cultured for 7 to 12 days of new-born Wistar rat were selected as objectives. Patch clamp whole-cell recording technique was used on the hippocampus neurons cultured for 7 to 12 day. to record the delayed rectifier potassium current to analyze the basic electrophysiological characteristics. The effects of melatonin of the concentrations of 1 nmol/L, 10 nmol/L, 100 nmol/L, 1 mol/L, 10 mol/L, 100 mol/L, and 1 mmol/L on the amplitudes and kinetics of delayed rectifier potassium currents were investigated.


RESULTS
With different voltage protocols and specific blockers of potassium channel (4-AP and TEA) a delayed rectifier potassium current that activated and inactivated slowly and had the outward rectifying characteristics (Ik) from the outward potassium currents in cultured new-born hippocampus neurons was separated. The effect of melatonin on the delayed rectifier channel was rapid, reversible and voltage-dependent Melatonin had no effect on the kinetic characteristics of the I -V curve. Melatonin increased the potassium current concentration-dependently. 1 - 100 nmol/L melatonin increased the amplitude of potassium current gradually; the effects of 1 - 100 micromol/L melatonin on the potassium current increased concentration-dependently, while the action of 1 mmol/L melatonin decreased.


CONCLUSIONS
Melatonin reversibly increases the rectifier delayed potassium currents of the cultured hippocampus neurons of new-born rat. This may be involved in some aspects of physiological and pathological significance of potassium currents.
Yin
Yi-qing
YQ
Department of Anesthesia, China-Japan Friendship Hospital, Beijing 100029, China. yyq518@sina.com
Luo
Ai-lun
AL
Guo
Xiang-yang
XY
Zheng
Jian-quan
JQ
Ren
Hong-zhi
HZ
Ye
Tie-hu
TH
Huang
Yu-guang
YG
D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D002492:Central Nervous System Depressants / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D006624:Hippocampus / Q000166:cytology; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D018408:Patch-Clamp Techniques; D024642:Potassium Channels, Voltage-Gated / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
D002492:Central Nervous System Depressants; D024642:Potassium Channels, Voltage-Gated; D008550:Melatonin