Abstract: The experiment was used Ca2+ import agent Ionomycin to establish intrafusal muscle cell calcium overload model of soleus muscle in rats. The confocal laser scanning microscopy was adopted to observe the effects of different concentrations of Ionomycin on resting intracelluar calcium in intrafusal fibers of rats′ soleus muscle. After administration of 2 mol/L Ionomycin, the resting intracelluar calcium in intrafusal fibers of rats′ soleus muscle increased slowly（P<0.01）, and (2.67±0.43) min later after reaching the peak value, the maximum value of MFI decreased by 50%. After administration of 5 μmol/L Ionomycin, the resting intracelluar calcium in intrafusal fibers of rats′ soleus muscle increased rapidly （P<0.01）, and (6.26±0.87) min later after reaching the peak value, the maximum value of MFI decreased by 50%. Ionomycin of 2 μmol/L can form a short-term calcium overload in intrafusal cells. Ionomycin of 5 μmol/L can establish a stable intrafusal muscle cell calcium overload model of soleus muscle in rats. This study provides valuable information for the study of rat muscle spindle physiology and the experimental study of calcium and weightlessness.

Key words: Ionomycin, Ca2+, muscle spindle, soleus muscle