Fig. 7. Calcium release experiments in embryonic and fetal myoblasts. Embryonic (a-b) and fetal (c-d) myoblasts after 4 days of culture under differentiating conditions were loaded with Fluo 3 AM and analyzed by a confocal laser microscope. Stimulation with either 10 µM carbachol and 40 mM caffeine exerted a transient increase on the intracellular calcium concentration in both embryonic (a) and fetal (c) myoblasts. Treatment with 300 µM ryanodine abolished caffeine- but not carbachol-induced calcium release in both embryonal (b) and fetal (d) myoblasts.