Ca2+ from A/A-induced NMDA channel activation structurally and functionally damages mitochondria. (A) Untreated (live) RGM1 cells were incubated with Rh 123 to measure mitochondrial membrane potential (Contr). Membrane potential was also measured for 10–120 min during A/A exposure (NH4Cl) with or without BAPTA-AM (B-AM). (B) At the end of the experiment in A, ATP was measured or (C) cells were lightly fixed and incubated with anti-COX (green). n ≥ 3; *P < 0.05, ** P < 0.01, *** P < 0.001, ND, not different; comparisons as indicated by brackets; scale bar, 20 µm.