Objective To investigate the intracellular calcium ion release and the system of calcium channel by 1,25 (OH)2D3stimulus, and the effect of mechanical pressure on it in rabbit mandibular condylar chondrocytes (MCC)in vitro. Methods In vitrocultured MCC from two-week-old New Zealand rabbits were incubated under 20 g/L heparin, 1 g/L procaine, continuous pressure of 90 kPa for 60 min and 360 min in a hydraulic pressure controlled cellular strain unit. With the Fluo-3/AM probe loaded, 1,25(OH)2D3was added to the medium and then the intracellular calcium level was detected by a laser confocal scanning microscope.Results Intracellular calcium concentration increased inMCC treated with 1,25(OH)2D3, 1,25(OH)2D3 and procaine, while it didn′t change in heparin treated group. Calcium in group under continuous pressure of 90 kPa for 60 min was also increased, even higher than the group stimulated only with 1,25(OH)2D3. Intracellular calcium in group treated with continuous pressure of 90 kPa for 360 min showed no significant difference compared to the control and even decreased at the end of the recording period.Conclusion 1,25(OH)2D3could stimulate the intracellular calcium release channel of inositol triphos- phate (IP3) receptor open in MCCin vitroand increases the level of intracellular calcium concentration. Pretreatment of definite mechanical pressure could modulate the sensitivity of IP3 channel to 1,25(OH)2D3stimulus.
