Fig. 4. Xestospongin C (Xc) inhibited isoflurane-induced cytotoxicity and calcium elevations in mutated Huntington disease (HD) knocked-in striatal cells. (  A ) Representative images of phase contrast (PC) or propidium iodide (PI) staining of HD or wild-type (WT) striatal cells at 24 h after completion of treating cells with 2.4% isoflurane for 24 h.  Scale bar = 100 μm. (  B ) Isoflurane at 2.4% for 24 h significantly increased percentage of cell damage determined by PI staining in HD knocked-in but not in WT striatal cells. Data represent mean ± SE of 18 repeats from three separate experiments. *  P < 0.05 compared with control in HD striatal cells. (  C ) Pretreatment of 100 nm Xc for 30 min abolished the MTS reduction induced by 2.4% isoflurane for 24 h in HD striatal cells. Data represent mean ± SE from 12 repeats of three separate experiments. *** or ###  P < 0.001 compared with control or isoflurane treatment alone. (  D ) Representative tracing reveals averaged isoflurane-evoked elevation of cytosolic calcium concentration ([Ca²⁺]^c) with or without pretreatment of Xc in the absence of extracellular calcium in both WT and HD cells. (  E ) Isoflurane at 2.4% induced significantly higher peak elevation of [Ca²⁺]^cin the absence of extracellular calcium in HD knocked-in than in WT striatal cells. Xc (1 μm) nearly abolished isoflurane-induced peak elevation of [Ca²⁺]^cin the absence of extracellular calcium in both WT and HD striatal cells. Data represent mean ± SE from three separate experiments. **  P < 0.01 compared with isoflurane treatment alone without Xc pretreatment. ##  P < 0.01 compared with WT striatal cells treated with isoflurane alone. ISO = isoflurane; MTS = 3-(4,5-dimethylthiazol-2-yl)-5-(3carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt.