ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effect of unaggregated Abeta(25.35) on delayed rectifier potassium current (I(K)) in neonatal rat hippocampal CA3 pyramidal neurons.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>The inhibitory effect of unaggregated Abeta(25-35) on I(K) may be a possible mechanism involved in the pathogenesis of Alzheimer's disease.</p>