Key result
Muscle regeneration in adult Xenopus laevis after cardiotoxin injury involves a precocious larval to fast heavy chain transition without thyroid hormone influence, indicating a myogenic program distinct from normal development.
Muscle regeneration in adult Xenopus laevis follows a different myogenic program than normal development, characterized by precocious expression of fast myosin heavy chains independent of thyroid hormone.
Does not support clinical changes in muscle repair; leaves open distinct myogenic programs in mammalian models.
The anterior brachial muscle of Xenopus laevis forelimb was characterized as a fast-type muscle composed of type II fibers exclusively. Larval and adult muscles showed three distinct isomyosins composed by two different heavy chains, HCl and HCf, respectively, associated with the same fast light chains. Muscle regeneration was examined after degeneration of the myofibers by injection of cardiotoxin, a snake toxin. 24 h after the injury no myofibers and no myosin were detected. New myosins of larval and adult fast types started to be synthesized two weeks after the injury, during a stage of proliferation of mononucleated cells. 1 month after the injury, the regenerated muscles which showed structural differences with the normal muscle contained only fast isomyosins. The precocious larval to fast heavy chain transition observed in regenerating muscles of the adult X. laevis without any thyroid hormone influence shows that the myogenic program in adult muscle regeneration is regulated by factors that are different from those regulating normal development.
No takes yet. Share an insight, caveat, or question.
Saadi et al. (1994) studied Muscle injury. Cardiotoxin injection vs. Normal uninjured muscle was evaluated on Myosin isoform expression and morphological changes during muscle regeneration. Muscle regeneration in adult Xenopus laevis after cardiotoxin injury involves a precocious larval to fast heavy chain transition without thyroid hormone influence, indicating a myogenic program distinct from normal development.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: