Cell-attached patch-clamp recordings on native striated myofibers from adult dystrophic mdx mice revealed a higher occurrence and open probability compared to non-dystrophic wild-type myofibers of a 30 pS voltage-insensitive Ca2+-permeable channel, inhibited by Gd3+, streptomycin and ruthenium red. Myofibers from in vivo exercised animals had higher channel occurrence and/or open probability. Insulin-like growth factor 1 (3.3 nM) induced and/or enhanced channel activity, via PI3 kinase, in wild-type but not in mdx myofibers. Interestingly, in both genotypes the current was silenced by db-cAMP or pentoxifylline, a phosphodiesterase inhibitor. The channel activity/occurrence in pentoxifylline-treated exercised mdx (50 mg/kg/day i.p. for 4-8 weeks) overlapped that of exercised wild-type mice. Thus, a growth factor-sensitive current, likely due to a TRP channel, is activated in vivo by exercise in native striated fibers; its deregulation in the absence of dystrophin may contribute to Ca2+ homeostasis alteration. The possibility to pharmacologically counteract abnormal channel activity discloses important therapeutic application.

译文

:成年营养不良mdx小鼠的天然横纹肌纤维的细胞附着膜片钳记录显示,与非营养性野生型肌纤维相比,不受30 pS电压敏感性Ca2渗透的通道受Gd3,链霉素抑制的发生率和开放概率更高和钌红色。来自体内运动动物的肌纤维具有较高的通道发生率和/或开放概率。胰岛素样生长因子1(3.3 nM)通过PI3激酶在野生型中诱导和/或增强了通道活性,但在mdx肌纤维中却没有。有趣的是,在这两种基因型中,电流都被db-cAMP或磷酸二酯酶抑制剂己酮可可碱沉默。己酮可可碱治疗的运动型mdx(50 mg / kg /天i.p.,持续4-8周)的通道活性/发生与运动的野生型小鼠的通道活性/发生重叠。因此,可能是由于TRP通道引起的对生长因子敏感的电流通过在天然横纹肌中运动而在体内被激活。在缺乏肌营养不良蛋白的情况下,其失调可能导致Ca2稳态改变。在药理学上抵消异常通道活性的可能性公开了重要的治疗应用。

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