Virchows Archiv

, Volume 446, Issue 3, pp 265–269

Myocardial ultrastructure in cardiac hypertrophy induced by thyroid hormone—an acute study in rats

  • Li Wen Hu
  • Edson Aparecido Liberti
  • Maria Luiza Morais Barreto-Chaves
Original Article

DOI: 10.1007/s00428-004-1175-1

Cite this article as:
Hu, L.W., Liberti, E.A. & Barreto-Chaves, M.L.M. Virchows Arch (2005) 446: 265. doi:10.1007/s00428-004-1175-1

Abstract

The early responses of the myocardium ultrastructure under thyroid dysfunction conditions, hemodynamic parameters, cardiac hypertrophy and ultrastructural evaluations were performed in hypothyroid and hyperthyroid rats submitted to different doses [T4–25 and T4–100; 0.025 mg and 0.1 mg kg−1 body weight (BW)·per day, respectively)]. All groups were treated for 7 days. The animals were sacrificed, the hearts were excised and weighed and the left ventricle tissue samples were processed for transmission election microscopy. Systolic blood pressure (SBP) was not altered by administration of T4. An increased heart rate and ratio of heart weight to body weight (HW/BW) were found in the hyperthyroid rats. However, the SBP and HW/BW decreased significantly in hypothyroid rats. No significant ultrastructural alterations were detected when the hypothyroid and T4–25 groups were compared with the control group. Alterations of cardiomyocytes nuclei of these groups were also not detected. Notably, disorganization of intercellular junctions was observed in many cardiomyocytes of T4–100 group. The present results indicate that in the early stages of hyperthyroidism, the cardiac hypertrophy development was mainly due to direct effects of thyroid hormone. Despite cardiac hypertrophy development, there is no ultrastructural evidence of myocardial degeneration.

Keywords

Thyroid hormone Cardiac hypertrophy Cardiomyocytes Transmission electron microscopy 

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Li Wen Hu
    • 1
  • Edson Aparecido Liberti
    • 1
  • Maria Luiza Morais Barreto-Chaves
    • 1
  1. 1.Laboratory of Cellular Biology and Functional Anatomy, Department of AnatomyBiomedical Sciences Institute, University of São PauloSão PauloBrazil

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