Thyroid hormone at supra-physiological dose optimizes cardiac geometry and improves cardiac function in rats with old myocardial infarction.
JOURNAL OF PHYSIOLOGY AND PHARMACOLOGY : AN OFFICIAL JOURNAL OF THE POLISH PHYSIOLOGICAL SOCIETY 2009;
60:49-56. [PMID:
19826181]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 07/17/2008] [Accepted: 07/15/2009] [Indexed: 05/28/2023]
Abstract
Thyroid hormone (TH) is critical in cardiac cell differentiation (regulating contractile proteins and cell geometry) and this effect could be potentially exploited therapeutically in reversing the process of de-differentiation which underlies postischemic cardiac remodeling. Acute myocardial infarction was induced in male Wistar rats by ligating left coronary artery (AMI, n=8), while sham operated animals served as control (SHAM, n=8). 13 weeks after AMI, TH was administered in a group of animals for 4 weeks (AMI-THYR, n=9). TH significantly increased beta-MHC and decreased alpha-MHC expression in the myocardium. This response was accompanied by changes in cardiac geometry: sphericity index, (SI, long to short axis ratio) was found to be 1.95 (SEM, 0.02) in SHAM, 1.51(0.03) in AMI and 1.64(0.03) in AMI-THYR, p<0.05. As a consequence, cardiac function was significantly improved: left ventricular ejection fraction (EF%) was 74.5% (SEM, 2.8) in SHAM vs 29.5% (2.1) in AMI, and 40.0% in AMI-THYR, p<0.05. Furthermore, +dp/dt and -dp/dt were 4250 (127) and 2278 (55) in SHAM vs 2737(233) and 1508 (95) in AMI vs 3866 (310) and 2137(111) in AMI -THYR, respectively, p<0.05. TH treatment partially reverses cardiac dysfunction in rats with old myocardial infarction by favorably changing cardiac chamber geometry and expression of myosin isoforms. Thyroid hormone, unlike current treatments, appears to be a paradigm of therapeutic intervention which aims at restoring cardiac geometry and may prove new effective treatment for heart failure.
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