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Cardiomyocyte aging and hypertrophy: atrial and ventricular changes in normal and myopathic Syrian hamsters
J Gilloteaux1, J J Bissler, P Kondolios
1Department of Anatomy, Northeastern Ohio Universities College of Medicine, Rootstown.
Insights
Cardiomyopathic hamsters exhibit significant cardiac hypertrophy, with atrial and ventricular cells enlarging even as the heart decompensates. This study details the cellular changes in cardiac eccentric hypertrophy.
Area of Science:
- Cardiology
- Cell Biology
- Pathology
Background:
- Cardiac eccentric hypertrophy involves complex cellular and metabolic changes.
- Understanding these alterations is crucial for managing heart conditions.
Purpose of the Study:
- To compare atrial and ventricular myocyte dimensions in cardiomyopathic (Bio 14.6) and control (F1b) Syrian hamsters.
- To examine the histopathology of cardiac eccentric hypertrophy using electron microscopy.
Main Methods:
- Comparative analysis of myocyte diameters (atrial and ventricular) between hamster strains.
- Histopathological examination via electron microscopy.
Main Results:
- Ventricular myocyte diameter increased with age in both strains, but was significantly greater in Bio 14.6 hamsters.
- Bio 14.6 hamsters showed atrial myocyte hypertrophy preceding ventricular changes.
- Histopathology revealed amitotic myocardial divisions, focal myocyte necrosis, and sarcoplasmic widening of Z-lines in Bio 14.6 hearts.
Conclusions:
- The cardiomyopathic heart (Bio 14.6) shows continued fiber hypertrophy despite cardiac decompensation.
- Cellular changes include myocyte necrosis and altered sarcomere structure.
- Atrial myocyte hypertrophy can precede ventricular changes in this model of cardiac eccentric hypertrophy.
Abstract:
Cardiac eccentric hypertrophy is associated with complex architectural and metabolic alterations. Atrial and ventricular myocyte diameters in cardiomyopathic (Bio 14.6) and age-matched control (F1b) Syrian hamsters were compared and histopathology was examined by electron microscopy. The mean diameter of ventricular myocyte diameters increased with age in both F1b and Bio 14.6 hamsters. Significantly greater hypertrophy was noted in the Bio 14.6 left ventricle myocytes than the F1b. Histo- and cytopathologic findings included amitotic myocardial divisions and focal myocyte necrosis in Bio hearts. Sarcomere length appeared to be similar across age and strain; however, wider sarcomeres were found in conjunction with wider diameters of myopathic left ventricle myocytes. Moreover, F1b hamsters' atrial myocytes maintained a static diameter, while those of the Bio 14.6 showed hypertrophy even preceding ventricular changes. These findings indicated that the cardiomyopathic heart is characterized by a continued fiber hypertrophy despite cardiac decompensation. Other histopathological findings included amitotic myocardial divisions, focal necrosis and sarcoplasmic widening of Z-lines. In addition, vascular smooth muscles of Bio 14.6 demonstrated vacuolization.