We developed a new method for the quantitative determination of myosin heavy chain (MyHC) isoforms taking advantage of immunochemical differences and based on the ELISA principle. In the present paper we compare anal ysis of MyHC isoforms using the SDS-PAGE and the ELISA methods in the same samples of adult female inbred Lewis strain euthyroid, hyperthyroid and hypothyroid rats. In all thyroid states, the same composition and corresponding changes of MyHC isoforms were determined using both methodological approaches in the slow soleus and the fast extensor digitorum longus muscles. Our results showed that ELISA can be used for a “semi-quantitative” or “comparative” measurement of MyHC isoforms in multiple muscle samples, but that it is neither more exact no r faster compared to SDS-PAGE., Jan Říčný., and Obsahuje bibliografii a bibliografické odkazy
We examined the effects of the unilateral heterochronous isotransplantation on the fiber type composition and myosin heavy chain (MyHC) isoform content of unoperated slow soleus and fast extensor digitorum longus muscles of female inbred Lewis strain rats. Comparison was made between “control” unoperated muscles of experimental rats (after intramuscular transplantation surgery) with the corresponding muscles of completely naive (unoperated) rats of three age groups (5-, 8- and 14-month-old). This was done in order to ascertain whether these muscles can be used as reliable controls to the transplanted and host muscles for our ongoing grafting experiments. The fiber type composition was determined by assessing the histochemical reaction for myofibrillar adenosine triphosphatase, the MyHC isoform content was determined immunocytochemically using monoclonal antibodies specific to different MyHC isoforms and by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Our experiments show that the heterochronous intramuscular isotransplantation procedure had no significant effect on the fiber type composition and MyHC isoform content of the “control” unoperated muscles of the experimental rats when compared to the corresponding muscles of the naive animals. Furthermore, the duration and type of isotransplantation did not also lead to differences among corresponding “control” muscles of experimental animals. We conclude that the unoperated muscles of the experimental rats can be used as controls in our current transplantation project dealing with long-term grafting experiments., T. Soukup, V. Smerdu, G. Zachařová., and Obsahuje seznam literatury
Expression of the muscle phenotype is the result of interaction between intrinsic and extrinsic factors, the latter including innervation, mechanical influences and hormonal signals. This minireview summarizes some of the current knowledge regarding the regulation of myosin heavy chain (MHC) isoform transitions during muscle development and regeneration. It describes the role of genetic factors, neural and mechanical influences and it focuses on the contribution of thyroid hormones to the differentiation of muscle fiber phenotypes as shown by the regulation of the expression of MHC isoforms and development of myofibrillar ATPase activity. Finally, it shortly summarizes results regarding the differentiation of MHC isoforms in regenerated muscle fibers of the graft after heterochronous isotransplantation in rats with different thyroid status., T. Soukup, I. Jirmanová., and Obsahuje bibliografii