Intracellular Ca²⁺ store content is similar in FDB fibers from WT and IT/+ mice. (A) Representative Fura-FF traces in FDB fibers from WT and IT/+ mice during successive applications of 500 µM 4-CMC and ICE (10 µM ionomycin, 30 µM CPA, and 100 µM EGTA/0 Ca²⁺ Ringer’s solution). (B) Average (±SEM) peak Fura-FF responses to 4-CMC in FDB fibers from WT (n = 10; left) and IT/+ (n = 13; right) mice. (C) Average (±SEM) peak rate of change in Fura-FF ratio (F₃₄₀/F₃₈₀) during 4-CMC application in FDB fibers from WT (n = 10; left) and IT/+ (n = 13; right) mice. (D) Average (±SEM) peak ICE responses in FDB fibers from WT (n = 10; left) and IT/+ (n = 13; right) mice. †, P < 0.05.