The acute effects of beta-amyloid (25-35) and (1-40) on high voltage activated calcium channels were compared in CA1 pyramidal cells of adult mouse hippocampal slices using the whole-cell patch-clamp recording. Bath application of oligomeric beta-amyloid (25-35) reversibly increased the barium current (I(Ba)) to 1.61 (normalized amplitude), while oligomeric beta-amyloid (1-40) reversibly enhanced the I(Ba) to 1.74. Reverse-sequence beta-amyloid [(35-25) and (40-1)] had no effect. The effect of beta-amyloid (25-35) was blocked by nifedipine, a selective antagonist of L-type calcium channels. In contrast, the effect of beta-amyloid (1-40) was not blocked by nifedipine and I(Ba) was enhanced to 4.96. It is concluded that these oligomeric peptides may act through different types of calcium channels and/or receptors. The toxicity of Abeta(25-35) implicates a potentiation of L-type calcium channels while the one of Abeta(1-40) is related to an increase of non-L-type calcium channels, which may involve an increase in transmitter release.
