Fig. 8.

Ability of HBD_org to trigger Ca²⁺ release from intracellular stores. Differentiated C₂C₁₂ myotubes grown on laminin-coated glass bottom chambers were loaded with fluo 3-AM (5 μM) for 30 min at 37°C, washed, and placed on the stage of a laser confocal microscope (Zeiss Confocal LSM 410 confocal microscope equipped with an Argon-Krypton Laser, 25 mW argon laser, 2% intensity, Thornwood, NJ). A: caffeine (10 mM; i) and HBD_org (50 μg/ml; ii, and 250 μg/ml; iv) were added to the chambers, and Ca²⁺ transients recorded. iii: Three minutes after addition of 50 μg/ml HBD_org and Ca²⁺ transient generation, caffeine (10 mM) was added. v: In separate experiments, differentiated C₂C₁₂ cells were incubated with 50 μM ryanodine 20 min at 37°C before loading with fluo 3-AM and exposure to 250 μg/ml HBD_org. B: fold increase in cytoplasmic Ca²⁺ following addition of HBD_org (50 and 250 μg/ml, with and without ryanodine). Values are means ± SE of peak Ca²⁺ release for >10 cells from 4 separate experiments. *Significantly different from 50 μg/ml HBD_org (P < 0.05). **Significantly different from 50 μg/ml HBD_org and 250 μg/ml HBD_org (P < 0.05).