Fig. 6.

Frequency of Ca²⁺ events in dedifferentiated adult FDB fibers decreases with addition of Ca²⁺ channel blockers. All fibers were cultured for 6–7 days in CoCl₂-free, nifedipine-free, serum-containing medium before each experiment. A: fibers cultured in serum-containing media were bathed in Ringer solution and imaged both before and after the addition of 5 mM CoCl₂ as indicated. B: time course of resting fiber fluorescence in the same fibers both before and after the addition of CoCl₂. C: fibers cultured in serum-containing media were bathed in Ringer solution and imaged both before and after the addition of 5 μM nifedipine as indicated. D: time course of resting fiber fluorescence in the same fibers both before and after the addition of nifedipine. E: fibers cultured in serum-containing media were bathed in Ringer solution and imaged for spark activity without Ca²⁺ channel blocker treatment. F: time course of resting fiber fluorescence in the same fibers without Ca²⁺ channel blocker treatment; n = 21 in A and B, n = 10 in C and D, and n = 10 in E and F. Statistical significance was determined using a 1-way ANOVA test (P < 0.05). Groups with the same letter exhibit significant difference from each other.