Inhibitory effect of unaggregated amyloid beta protein (25-35) on delayed rectifier potassium current in rat hippocampal CA3 pyramidal neurons

To investigate the effect of unaggregated Abeta(25.35) on delayed rectifier potassium current (I(K)) in neonatal rat hippocampal CA3 pyramidal neurons.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.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.The inhibitory effect of unaggregated Abeta(25-35) on I(K) may be a possible mechanism involved in the pathogenesis of Alzheimer's disease.PubMed03301-43