Resumo

PRADOS, J. et al. IMMUNOHISTOCHEMICAL ANALYSIS OF THE CHANGES IN THE a-ACTININ EXPRESSION DURING CARDIAC CHICK DEVELOPMENT. Rev. chil. anat. [online]. 1998, vol.16, n.2, pp. 255-261. ISSN 0716-9868.  doi: 10.4067/S0716-98681998000200013.

SUMMARY: The cytoskeleton of muscle cell is a complex network of proteins which expression pattern is related with the differentiation process. The a-actinin, a protein which plays an important role in the muscular contraction, is essential to the sarcomeres conformation, serving as an anchoring point or center of organization for the preformation of actin filaments. The modulation of the a-actinin expression during the muscular cell maturation, has an important morphofuntional implications to the myocardiocytes. Immunofluorescence studies on cryotome sectins of chick embryo hearts and myocardiocyte cultures showed that a-actinin expression was weak in early stages (Hamburger Hamilton stage 18), staining the cellular membrane of myocardiocytes. A diffuse label for citoplasmic compartment was observed in these stages. a-actinin expression increased during the chick cardiac development. We found in Hamburger Hamilton stage 29, an intense label for the ventricular myocardium coinciding with the presence of a-actinin along the myocardiocyte myofibrills. Analysis of the Hamburger Hamilton stage 36 showed an increase in the a-actinin expression but without changes in their immunolocalization. The expression pattern of a-actinin during the cardiac development indicated that this protein is a good marker to the degree of myogenic differentiation, the importance of the 29 HH stage to the morphofuntional maturation of myocardiocytes and, the differential expression on the atrial and ventricular myocardium.

Palavras-chave : a-actinin; Cytoskeleton; Cardiac development; Chick embryo.