Modification of electrophysiological properties of rat heart with age

Meo, S. Di; Rosaroll, P. de Martino; Piro, M. C.; Leo, T. De

doi:10.3109/13813459209035251

Cited by 5 publications

(3 citation statements)

References 15 publications

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“…This is in accordance with observations of age-dependent effects on heart action potential parameters observed to parallel age-related thyroid states (47,48). This observation might relate to a down-regulation of thyroid hormone receptors with aging (49).…”

Section: Hypothyroidsupporting

confidence: 80%

Thyroid Hormone Effects on Sensory Perception, Mental Speed, Neuronal Excitability and Ion Channel Regulation

Dietzel¹,

Mohanasundaram²,

Niederkinkhaus³

et al. 2012

Thyroid Hormone

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Section: Hypothyroidsupporting

confidence: 80%

Thyroid Hormone Effects on Sensory Perception, Mental Speed, Neuronal Excitability and Ion Channel Regulation

Dietzel¹,

Mohanasundaram²,

Niederkinkhaus³

et al. 2012

Thyroid Hormone

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“…General features of thyroid hormone action include enhanced contraction strength/velocity and increased speed of diastolic relaxation in the hyperthyroid state [5,21,22]. In contrast, these mechanisms are decreased in hypothyroid animals [10]. Accordingly, Ferreira et al [11] have observed the predominant appearance of myofibrillar disarray, associated with disorganization of cytoskeletal proteins in the deep myocardium.…”

Section: Introductionmentioning

confidence: 94%

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

Liberti

Barreto‐Chaves

2005

Virchows Arch

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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.

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“…General features of thyroid hormone action include enhanced contraction strength/velocity and increased speed of diastolic relaxation in the hyperthyroid state (Biondi et al, 2000;Cohen et al, 1981;Dillmann et al, 1987). In contrast, inotropism and chronotropism are decreased in hypothyroid animals (Di Meo et al, 1992;Kragie et al, 1993). The acute gain of heart function driven by thyroid hormone may evolve, however, to hypertrophy, a completely opposite scenario that eventually leads to severe loss of function, including congestive heart failure and atrial arrhythmia (Ebisawa et al, 1994;Fadel et al, 2000;Klein and Ojamaa, 2001a;Sussman, 2001;Woeber, 1992).…”

Section: Introductionmentioning

confidence: 99%

Temporal and topographic ultrastructural alterations of rat heart myofibrils caused by thyroid hormone

Ferreira

L’Abbate

Abrahamsohn

et al. 2003

Microscopy Res & Technique

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In order to further our understanding regarding the temporal and topographic ultrastructural aspects of the myocardium under thyrotoxicosis, thyroxine (T4; 25 and 100 microg/100 g bw) was administered to young rats 24 hours after birth until 15 days. The animals were then sacrificed, the hearts excised and weighed, and the ventricle tissue samples were then processed for confocal and transmission electron microscopy. At 48/72 hours and 1 week after initiation of T4 treatment with 100 microg/100 g bw, numerous lamellar bodies (probably formed by phospholipids) progressively accumulated in the heart. These bodies were observed in the cytosol, inside mitochondria and in the extracellular matrix. At 2 weeks of T4 treatment with 100 microg/100 g bw, lamellar bodies were virtually absent. Changes in cell shape, disorganization of intercellular junctions, and substantial myofibrillar disarray were observed in many cardiomyocytes. A gradient of myofibrillar disarray, which increased in abundance and intensity from the endocardium to the epicardium, was also observed. Immunocytochemical staining for desmin showed that the arrangement of this protein was disorganized in many cells of T4-treated rats as compared with normal ones, confirming ultrastructural data. The predominant appearance of myofibrillar disarray, associated with disorganization of cytoskeletal proteins in the deep myocardium, may be due to higher mechanical wall stress and consequent higher metabolic demand. Alternatively, differential sensitivity of cardiomyocytes to thyroid hormone in different areas is also a possibility.

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Modification of electrophysiological properties of rat heart with age

Cited by 5 publications

References 15 publications

Thyroid Hormone Effects on Sensory Perception, Mental Speed, Neuronal Excitability and Ion Channel Regulation

Thyroid Hormone Effects on Sensory Perception, Mental Speed, Neuronal Excitability and Ion Channel Regulation

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

Temporal and topographic ultrastructural alterations of rat heart myofibrils caused by thyroid hormone

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