Figure 3.

Removal of Extracellular Ca²⁺ Reverses Cytoplasmic Calcium Accumulation and Prevents Axon Degeneration

(A) In vivo multiphoton maximum intensity projection of an acute EAE lesion (as ratiometric YFP/CFP images color coded for axonal [Ca²⁺]_cyt), shown before (top, Pre) and after (bottom, 4 h EGTA) removal of extracellular Ca²⁺.

(B) [Ca²⁺]_cyt plotted as YFP/CFP ratios of single-stage 0 (left) and stage 1 (right) axons before (Pre) and after (4 h EGTA) removal of extracellular calcium. Top: percentage of axons with [Ca²⁺]_cyt ≥3 SD above control mean, shown as mean ± SEM (tested per animal in n = 5 control and n = 5 EAE mice, paired t test).

(C) Axon fate of [Ca²⁺]_cyt-high stage 0 (left, 31 axons, 8 mice) and [Ca²⁺]_cyt-high stage 1 (right, 66 axons, 8 mice) axons over 4 h with (EGTA) and without (artificial cerebral spinal fluid [aCSF]) removal of extracellular Ca²⁺ (chi-square test).

Scale bar in (A), 25 μm. ^∗p < 0.05; ^∗∗p < 0.01; ^∗∗∗p < 0.001. See also Figure S3.