The calcitonin gene-related peptide (CGRP) restores an apparant normal ultrastructure in mdg/mdg muscle cells in vitro, including a normal triadic organization which is known to be essential for excitation-contraction (E-C) coupling. However, neither slow L-type Ca2+ channel activity nor E-C coupling, which are absent in mdg/mdg muscle, were re-established. These observations suggest a potential role of CGRP (and also ofcAMP as the intracellular messenger) in the morphological development of the muscle fiber.
