Thyroid Hormones and the Heart

摘要: Recent research has revealed some new and surprising aspects of thyroid hormone action. 1. Many the marked effects hormones can be explained by nuclear binding, alteration in gene expression, increaed mRNA formation subsequent enhancement protein synthesis. 2. Several enzymes carbohydrate fatty acid metabolism are stimulated. However, those involved oxidative pentose phosphate pathway, glucose-6-phosphate dehydrogenase 6-phosphogluconate dehydrogenase, not altered rat heart 3,3′,5-triiodo-L-thyronine. 3. The positive chronotropic inotropic 3,3′,5-triiodo-L-thyronine mediated catecholamines via an increased number β-adrenergic receptors, they abolished blockade with metoprolol. 4. This β-receptor blocker, however, does affect induced increase cardiac output, stimulation myocardial development hypertrophy. Thus, these alterations occur independently catecholamines. 5. hypertrophic response seems to exclusively result direct metabolism, but also consequence additional indirect factor such as hemodynamic load.