组胺H3受体降低电激发收缩的小鼠成肌细胞胞浆中钙离子浓度

目的:探讨组胺H3受体(H3R)在小鼠成肌细胞C2C12成肌分化过程及分化后的横纹肌细胞中的表达和可能发挥的作用。方法:诱导C2C12细胞成肌分化,测量H3R和分化晚期标志物肌球蛋白重链mRNA和蛋白的表达;分化过程中加入H3R拮抗剂ciproxifan,测量分化早期标志物desmin、中期标志物myogenin和肌球蛋白重链mRNA的表达。Fluo-4结合剂标记分化后的横纹肌胞内钙离子,测量双极交流电200 m A刺激下,H3R激动剂甲基组胺(RMe HA)对胞浆中钙离子浓度的影响。结果:H3R和肌球蛋白重链在成肌分化过程中表达量逐渐增加。Ciproxifan在成肌分化过程中对3种分化标志物mRNA的表达与对照组相比无差异(P0.05)。RMe HA在浓度10 nmol/L~100μmol/L刺激细胞5~20 min,可呈钟形降低因交流电引起的肌浆钙离子浓度的升高(P0.05),其中RMe HA 100 nmol/L在10 min和20 min对电刺激细胞中Ca2+的抑制百分率最高。相同浓度的RMe HA在20 min和10 min时对Ca2+的抑制率比其在5 min时高(P0.05)。结论:H3R可能在成肌分化过程中的作用不大,而在分化成熟细胞中可以降低电刺激引起的胞浆钙离子浓度的升高。

Histamine H3 receptor inhibited electrically evoked cytoplasmic calcium in differentiated skeletal C2C12 myoblasts

AIM: To explore the expression and possible function of histamine H3 receptor (H3R) in striated myogenesis and the differentiated C2C12 cells. METHODS: H3R and myogenesis late marker myosin heavy chain (MHC) were detected at mRNA and protein levels during C2C12 myogenesis. H3R antagonist ciproxifan was added and the expression of the myogenesis early marker desmin, intermediate markers myogenin and MHC was detected. Differentiated myoblasts were loaded with Fluo-4 calcium indicator dye and the effect of R-(a)-methylhistamine (RMeHA) on the cytoplasmic calcium concentration was determined under the 200 mA electrical stimulation. RESULTS: The expression of H3R and MHC was increased during myogenesis. Ciproxifan incubation had no influence on the 3 striated myogenesis mar-kers (P>0.05). In C2C12 myoblasts, RMeHA (10 nmol/L~100 μmol/L) effectively diminished cytoplasmic calcium peak when the cells were electrically paced (P<0.05). The best inhibitory effect of RMeHA was observed at dose of 100 nM for 10 min and 20 min, which was higher than that for 5 min (P<0.05). CONCLUSION: H3R might have little effect on the myogenic differentiation, but diminishes cytoplasmic calcium peak of the differentiated myoblasts under electrical stimulation.