[Inhibitory effect of unaggregated amyloid beta protein (25-35) on delayed rectifier potassium current in rat hippocampal CA3 pyramidal neurons].
OBJECTIVE
To investigate the effect of unaggregated Abeta(25.35) on delayed rectifier potassium current (I(K)) in neonatal rat hippocampal CA3 pyramidal neurons.


METHODS
The rat hippocampal neurons were enzymatically isolated from 10-11-day-old Wistar rat. The I(K) was recorded using whole-cell patch clamp technique.


RESULTS
The inhibitory effect of unaggregated Abeta(25-35) on I(K) was time-dependent, because I(K) significantly decreased from (6.987 +/- 1.152) nA to (2.540 +/- 0.349) nA after adding unaggregated Abeta(25-35) and reached a stabilized level after 5-7 min (n = 8, P <0.01). However, the inhibitory effect was not concentration-dependent, because the decrease of the I(K) amplitude in different concentration groups were all around 60%. Unaggregated Abeta(25-35) also remarkably affected the half-activation potential, which was (4.114 +/- 0.730) mV and (-5.463 +/- 0.950) mV before and after its application (n = 15, P <0.05); however, the slope factor of activation curve was not significantly changed.


CONCLUSIONS
The inhibitory effect of unaggregated Abeta(25-35) on I(K) may be a possible mechanism involved in the pathogenesis of Alzheimer's disease.
Li
Lin
L
Central Laboratory, the First Hospital, Peking University, Beijing 100034, China.
Liu
Zhen-Zhai
ZZ
He
Bing-Jun
BJ
Qi
Yu
Y
D000544:Alzheimer Disease / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D005260:Female; D006624:Hippocampus / Q000166:cytology*; D008297:Male; D051379:Mice; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D016229:Amyloid beta-Peptides; D011188:Potassium