Increase of Intracellular Free Calcium Inhibits the Afferent Discharges From Isolated Soleus Muscle Spindle in Rats

Yu Lei; Zhao Xuehong; Fan Xiaoli; Li Xueping

doi:10.16289/j.cnki.1002-0837.2019.05.002

Abstract：Objective To investigate the effects of the increase of intracellular free calcium on afferent discharges of isolated soleus muscle spindle in rats.Methods Twelve rats were randomly divided into three groups:the 2.0ion group,the 5.0ion group,and the dimethyl sulfoxide(DMSO) group.The isolated soleus muscle spindle of rats in 3 groups were separated.After incubation with 2μmol/L ionomycin in 2.0ion group and 5 μmol/L ionomycin in 5.0ion group respectively,the changes of free calcium concentration in soleus muscle spindle were observed by laser scanning confocal microscopy.The air-gap technique was used to observe the afferent discharge activities of rats' isolated soleus muscle spindle,and the changes of the afferent discharge activities in 3 groups were observed after treated with DMSO,2μmol/L,or 5 μmol/L Ionomycin respectively.Results Ionomycin (2 and 5 μmol/L) could significantly increase the level of resting calcium in intrafusal muscle of rats' soleus muscle,and the effect was concentration dependent (P＜0.01).Ionomycin (2 and 5 μmol/L) could significantly reduce the afferent discharges of single muscle spindle of soleus muscle (P＜0.05).5 μmol/L ionomycin could prolong the periodic interval of spontaneous discharge of single muscle spindle (P ＜ 0.05),and there was no significant changes on evoked discharges of muscle spindle after the adding of Succinylcholine chloride(Sch) with concentration of 50 mg/L.Conclusion Increased free calcium concentration in rat soleus muscle spindle can inhibit afferent discharges of muscle spindle.