Effects of berberine on potassium currents in acutely isolated CA1 pyramidal neurons of rat hippocampus.
The effects of berberine, an isoquinoline alkaloid with antiarrhythmic action, on voltage-dependent potassium currents were studied in acutely isolated CA1 pyramidal neurons of rat hippocampus by using the whole-cell patch-clamp techniques. Berberine blocked transient outward potassium current (IA) and delayed rectifier potassium current (IK) in a concentration-dependent manner with EC50 of 22.94+/-4.96 microM and 10.86+/-1.06 microM, Emax of 67.47+/-4.00% and 67.14+/-1.79%, n of 0.77+/-0.08 and 0.96+/-0.07, respectively. Berberine 30 microM shifted the steady-state activation curve and inactivation curve of IA to more negative potentials, but mainly affected the inactivation kinetics. Berberine 30 microM positively shifted the steady-state activation curve of IK. These results suggested that blockades on K+ currents by berberine are preferential for IK, and contribute to its protective action against ischemic brain damage.
Wang
Fang
F
Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology, Hong Kong Road 13, Wuhan, Hubei 430030, PR China. wf0322@hotmail.com
Zhao
Gang
G
Cheng
Lan
L
Zhou
Hong-Yi
HY
Fu
Li-Ying
LY
Yao
Wei-Xing
WX
D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D001599:Berberine / Q000494:pharmacology*; D020520:Brain Infarction / Q000188:drug therapy / Q000503:physiopathology / Q000517:prevention & control; D002545:Brain Ischemia / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D066298:In Vitro Techniques; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D018696:Neuroprotective Agents / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects* / Q000378:metabolism; D017966:Pyramidal Cells / Q000187:drug effects* / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D000889:Anti-Arrhythmia Agents; D018696:Neuroprotective Agents; D015221:Potassium Channels; D001599:Berberine