Figure 7

Effect of glutamate application on Ca²⁺ fluxes. Glutamate (10 μM) was applied to cortical neurons following daily treatment with 1 μM Aβ_1-40, and to age-matched un-treated control cells. Peak values of Ca²⁺ fluxes (A) and steady-state Ca²⁺ fluxes recorded 20 min after glutamate application (B) are shown for one, three, six, and eight days of treatment with Aβ. Glutamate application to the bath induced a mild Ca²⁺ influx in primary cortical neurons with peak values being not statistically different from the relevant Ca²⁺ peak values recorded from age-similar control cells one and three days after the treatment. However, treatment with soluble Aβ for six days and longer increased Ca²⁺ uptake by more than two-fold as compared with non-treated age-similar control cells (* - P < 0.05, t-test). While steady-state values of Ca²⁺ fluxes measured 20 min after the glutamate challenge were not statistically different from the relevant values of age-similar control cells even after six days of Aβ treatment (Figure 7B; P < 2.0 at n = 7), the calculated total amount of Ca²⁺ taken up by Aβ treated cells over 20 minutes of treatment with glutamate was 2.5-fold higher than in age-similar un-treated control cells (P < 0.05). Error bars represent SEM (n = 4-7).