Fig. 5.

Frequency of Ca²⁺ events in both normal and dedifferentiated adult FDB fibers and resting Ca²⁺ concentration ([Ca²⁺]) after various times in culture. A: fibers were cultured in either serum-containing media or serum-free media. Frequency of Ca²⁺ event fibers increases as fiber dedifferentiation increases. In serum-containing media, the no. of fibers included with normal appearance was 15, 20, 9, and 3 and 0, 0, 11, and 5 with dedifferentiated appearance at the successive time points, and in serum-free media was 25, 16, 19, and 10 with normal appearance and 0, 2, 5, and 7 with dedifferentiated appearance at the successive time points. Statistical significance was determined using a 2-way ANOVA test. Significance (P < 0.05) was found between the dedifferentiating fibers in serum-containing media and all the other groups at both days 5 and 7. B: intracellular resting [Ca²⁺] during fiber dedifferentiation. Bar graph summarizing mean resting [Ca²⁺] evaluated by ratiometric photometry in indo 1-loaded FDB fibers cultured in serum-containing media at four different stages (days 1, 3, 5, and 7) after fiber plating. Transmitted light images at top of each column shows the typical appearance of FDB fibers for each stage. Scale bar = 10 μm; nos. in parentheses represent sample size.