A Subpopulation of Rat Muscle Fibers Maintains an Assessable Excitation-Contraction Coupling Mechanism After Long-Standing Denervation Despite Lost Contractility

• DOI: 10.1097/nen.0b013e3181c18416
• Publication Date: 2009-11-17T08:28:48Z
• Authors: Roberta Squecco; Ugo Carraro; Helmut Kern; Amber Pond; Nicoletta Adami; Donatella Biral; Vincenzo Vindigni; Simona Boncompagni; Tiziana Pietrangelo; Gerardo Bosco; Giorgio Fanò; Marina Marini; Provvidenza M. Ab...; Elena Germinario; Daniela Danieli-B...; Feliciano Protasi; Fabio Francini; Sandra Zampieri
• Keywords: Contractility

To define the time course and potential effects of electrical stimulation on permanently denervated muscle, we evaluated excitation-contraction coupling (ECC) rat leg muscles during progression to long-term denervation by ultrastructural analysis, specific binding dihydropyridine receptors, ryanodine receptor 1 (RYR-1), Ca channels extrusion pumps, gene transcription translation Ca-handling proteins, in vitro mechanical properties electrophysiological analyses sarcolemmal passive L-type current (ICa) parameters. We found that response denervation: 1) isolated muscle is unable twitch has very small myofibers but may show a slow caffeine contracture; 2) only roughly half fibers with "voltage-dependent channel activity" are able contract; 3) ECC mechanisms still present and, part, functional; 4)ECC-related expression upregulated; 5) at any point, there more resistant than others atrophy disorganization apparatus. These results support hypothesis prolonged "resting" [Ca] drive degeneration stimulation-induced modulation mimic lost nerve influence, playing key role modifying muscle. Hence, these data provide molecular explanation for recovery occurs rehabilitation strategies developed based empirical clinical observations.