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Tissue-specific modulation of angiotensin-converting enzyme (ACE) in hyperthyroidism
M S Carneiro-Ramos1, V B Silva, R A S Santos
1Department of Cell and Developmental Biology, Institute of Biomedical Sciences, Universidade de São Paulo, São Paulo 05508-900, Brazil.
Peptides
|May 30, 2006
Summary
Thyroid hormones (TH) influence angiotensin-converting enzyme (ACE) activity differently across tissues. While renal ACE increased, cardiac ACE diminished in hyperthyroid rats, indicating tissue-specific transcriptional regulation.
Area of Science:
- Endocrinology
- Cardiovascular Physiology
- Molecular Biology
Background:
- Established interaction between the Renin-Angiotensin System (RAS) and thyroid hormones (TH).
- Need to understand the tissue-specific effects of TH on local enzyme activity and expression.
Purpose of the Study:
- To investigate the role of TH in the local regulation of Angiotensin-Converting Enzyme (ACE) activity and expression.
- To determine tissue-specific responses of ACE to TH administration in rats.
Main Methods:
- Administration of L-thyroxine (T4) at two doses (0.025 and 0.100 mg/kg/day) to adult male Wistar rats for 14 days.
- Evaluation of hemodynamic parameters, cardiac, and renal hypertrophy.
- Measurement of ACE activity (Fluorimetric assay) and mRNA levels (Northern blot) in serum, pulmonary, renal, and cardiac tissues.
Main Results:
- T4 administration increased systolic blood pressure (SBP) and heart rate (HR), inducing cardiac and renal hypertrophy.
- Pulmonary and serum ACE levels remained unchanged.
- Renal ACE activity and expression were significantly increased, while cardiac ACE activity and expression were decreased in hyperthyroid groups.
Conclusions:
- Thyroid hormones exert differential effects on ACE activity and expression in a tissue-specific manner.
- The observed changes in cardiac and renal ACE are mediated by tissue-specific transcriptional mechanisms.
- Highlights the complex interplay between thyroid hormone status and the local renin-angiotensin system.