Fig. 2.

Intracellular Aβ₄₂ reduces transient A-type K+ currents in primary hippocampal neurons. (A) Isolation of the transient A-type K⁺ current from a hippocampal neuron in the voltage-clamp configuration. The total outward current (upper trace; 1) was recorded during 300 ms voltage steps from −90 to +50 mV. To inactivate the transient K⁺ channel a prepulse to −30 mV (50 ms) was applied before the voltage step to +50 mV (middle trace; 2). The transient K⁺ current (lower trace; 3) was isolated by digital subtraction of the sustained current from the total outward current. (B) K⁺ current recorded in the presence of 5 mM of 4-APs, an A-type K⁺ current blocker (from the same neuron shown in A). (C) Representative traces showing the effect of 20 minutes intracellular application of Aβ₄₂ (left) or vehicle (right). (D) Time course of the transient A-type K⁺ current amplitudes during intracellular perfusion of Aβ₄₂ (black circles; n = 10) and vehicle (open circles; n = 10). (E) Bar graph summarizing data from experiments shown in C (average transient A-type K⁺ current at T₂₀ is expressed as percentage of transient A-type K⁺ current recorded at T0; iAβ42 n = 11; i-vehicle n = 10; iAβ42-1 n = 6; ** p < 0.001). Abbreviations: Aβ, amyloid β-protein; APs, action potentials.