Canato M, Dal Maschio M, Sbrana F, Raiteri R, Reggiani C, Vassanelli S, Megighian A
Department of Human Anatomy and Physiology, University of Padova, 35131 Padova, Italy.
J Biomed Biotechnol. 2010;2010:981945. doi: 10.1155/2010/981945. Epub 2010 Apr 8.
This study aimed to analyse the sarcolemma of Col6a1-/- fibers in comparison with wild type and mdx fibers, taken as positive control in view of the known structural and functional alterations of their membranes. Structural and mechanical properties were studied in single muscle fibers prepared from FDB muscle using atomic force microscopy (AFM) and conventional electrophysiological techniques to measure ionic conductance and capacitance. While the sarcolemma topography was preserved in both types of dystrophic fibers, membrane elasticity was significantly reduced in Col6a1-/- and increased in mdx fibers. In the membrane of Col6a1-/- fibers ionic conductance was increased likely due to an increased leakage, whereas capacitance was reduced, and the action potential (ap) depolarization rate was reduced. The picture emerging from experiments on fibers in culture was consistent with that obtained on intact freshly dissected muscle. Mdx fibers in culture showed a reduction of both membrane conductance and capacitance. In contrast, in mdx intact FDB muscle resting conductance was increased while resting potential and ap depolarization rate were reduced, likely indicating the presence of a consistent population of severely altered fibers which disappear during the culture preparation.
本研究旨在分析Col6a1基因敲除型纤维的肌膜，并与野生型纤维和mdx纤维进行比较。鉴于mdx纤维膜已知的结构和功能改变，将其作为阳性对照。使用原子力显微镜（AFM）和传统电生理技术，对取自趾长伸肌（FDB）的单根肌纤维进行结构和力学性能研究，以测量离子电导和电容。虽然两种类型的营养不良性纤维的肌膜形貌均得以保留，但Col6a1基因敲除型纤维的膜弹性显著降低，而mdx纤维的膜弹性增加。在Col6a1基因敲除型纤维的膜中，离子电导可能由于泄漏增加而升高，而电容降低，动作电位（ap）去极化速率降低。在培养纤维上进行的实验结果与在完整新鲜解剖肌肉上获得的结果一致。培养的mdx纤维显示膜电导和电容均降低。相比之下，在完整的mdx FDB肌肉中，静息电导增加，而静息电位和ap去极化速率降低，这可能表明存在大量严重改变的纤维，这些纤维在培养制备过程中消失。
