胞内游离钙离子浓度增加抑制大鼠离体比目鱼肌肌梭传入放电（英文）

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

目的探讨大鼠离体比目鱼肌胞内游离钙离子浓度增加对肌梭传入放电的影响。方法 12只大鼠随机分为3组,2.0ion组、5.0ion组、二甲基亚砜(dimethyl sulfoxide,DMSO)组。分离大鼠比目鱼肌单一肌梭,2.0ion组、5.0ion组分别给予2和5μmol/L钙离子导入剂伊吾诺霉素(ionomycin)孵育,采用激光扫描共聚焦显微镜观察肌梭内游离钙离子浓度的改变。采用空气隔绝法记录大鼠比目鱼肌单一肌梭传入放电活动,观察3组肌梭传入放电活动的变化。结果伊吾诺霉素(2和5μmol/L)能显著增加大鼠比目鱼肌梭內肌静息钙的含量,且呈浓度依赖性(P<0.01)。DMSO对大鼠比目鱼肌单一肌梭传入放电活动无明显影响。2和5μmol/L伊吾诺霉素可明显抑制比目鱼肌单一肌梭传入放电(P<0.05)。5μmol/L伊吾诺霉素可延长单一肌梭传入放电周期间隔(P<0.05),在此基础上给予50mg/L氯化琥珀酰胆碱(Sch)诱发肌梭传入发电,可见肌梭传入放电无明显改变。结论大鼠比目鱼肌梭內肌游离钙离子浓度的增加可抑制肌梭传入放电。

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 2.0 ion group,the 5.0 ion 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 2.0 ion group and 5μmol/L ionomycin in 5.0 ion 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 5μmol/L Ionomycin respectively.Results Ionomycin(2 and 5μmol/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 5μmol/L)could significantly reduce the afferent discharges of single muscle spindle of soleus muscle(P<0.05).5μmol/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.