Fig. 2.

In vivo properties of the somatic intracellular Ca²⁺ stores in silent, normal, and hyperactive cells from amyloid-depositing mice. (A) Maximum intensity projection image (155- to 161-μm depth) of layer 2/3 in the frontal/motor cortex of an AD mouse. Locations of 10 mM NMDA and 80 mM caffeine-containing pipettes are indicated. AF 594 (50 μM) was routinely added to all pipette solutions. (B) Caffeine-induced Ca²⁺ transient. Here and below, the triangle indicates the time point of application. The schematic illustrates parameters of Ca²⁺ transients analyzed in this study (amplitude, T-half, tau, and AUC). ΔF/F, relative change in fluorescence. Box-and-whisker plots illustrate amplitude (C), T-half (D), tau (E), and normalized AUC (F; AUC_Caffeine/AUC_{AF 594}) of caffeine-induced Ca²⁺ transients in silent (blue; n = 13 cells in five mice), normal (green; n = 21 cells in five mice), and hyperactive (red; n = 17 cells in five mice) cells in AD mice. Amplitude and normalized AUC are similar in the different cells types (one-way ANOVA: F_2,48 = 0.88, P = 0.42 for amplitude and F_2,48 = 1.68, P = 0.20 for normalized AUC). The T-half and tau of hyperactive cells are significantly higher [T-half; one-way ANOVA: F_2,48 = 6.24, P = 0.01 (hyperactive vs. silent cells), P = 0.01 (hyperactive vs. normal cells), and P = 0.99 (silent vs. normal cells); tau: F_2,48 = 6.49, P < 0.01 (hyperactive vs. silent cells), P = 0.01 (hyperactive vs. normal cells), and P = 0.99 (silent vs. normal cells)]. ns, not significant. (G) Evoked Ca²⁺ transients recorded from neurons labeled with respective numbers in A before, during, and after application of 400 μM CPA. (H) Maximum intensity projection image (169- to 175-μm depth) of layer 2/3 in the frontal/motor cortex of an AD mouse. The location of the pipette used for NMDA application (10 mM) is indicated. (I) NMDA-induced Ca²⁺ transients recorded from a hyperactive cell marked with an asterisk in H before (black), during (light gray), and after (dark gray) application of CPA. (J) Box-and-whisker plot illustrating the CPA effect on amplitude, T-half, tau, and normalized AUC of NMDA-induced transients in silent, normal, and hyperactive cells (n = 5 mice). All values obtained under CPA are normalized to respective control values. The dashed line is drawn at 100%. In the presence of CPA, there is no significant change in all parameters for all cell types [two-way repeated measures ANOVA: F_4,48 = 1.62, P = 0.18]. *P < 0.05 in D and E.