title: Thyroid hormone promotes remodeling of coronary resistance vessels.
abstract: Low thyroid hormone (TH) function has been linked to impaired coronary blood flow, reduced density of small arterioles, and heart failure. Nonetheless, little is known about the mechanisms by which THs regulate coronary microvascular remodeling. The current study examined the initial cellular events associated with coronary remodeling induced by triiodothyronine (T3) in hypothyroid rats. Rats with established hypothyroidism, eight weeks after surgical thyroidectomy (TX), were treated with T3 for 36 or 72 hours. The early effects of T3 treatment on coronary microvasculature were examined morphometrically. Gene expression changes in the heart were assessed by quantitative PCR Array. Hypothyroidism resulted in arteriolar atrophy in the left ventricle. T3 treatment rapidly induced small arteriolar muscularization and, within 72 hours, restored arteriolar density to control levels. Total length of the capillary network was not affected by TX or T3 treatment. T3 treatment resulted in the coordinate regulation of Angiopoietin 1 and 2 expression. The response of Angiopoietins was consistent with vessel enlargement. In addition to the well known effects of THs on vasoreactivity, these results suggest that THs may affect function of small resistance arteries by phenotypic remodeling of vascular smooth muscle cells (VSMC).
authors.affiliation: Cardiovascular Health Research Center, Sanford Research/University of South Dakota, Sioux Falls, South Dakota, United States of America.
authors.forename: Olga V
authors.initials: OV
authors.lastname: Savinova
authors.forename: Yingheng
authors.initials: Y
authors.lastname: Liu
authors.forename: Garth A
authors.initials: GA
authors.lastname: Aasen
authors.forename: Kai
authors.initials: K
authors.lastname: Mao
authors.forename: Nathan Y
authors.initials: NY
authors.lastname: Weltman
authors.forename: Brett L
authors.initials: BL
authors.lastname: Nedich
authors.forename: Qiangrong
authors.initials: Q
authors.lastname: Liang
authors.forename: A Martin
authors.initials: AM
authors.lastname: Gerdes
mesh_terms: D042682:Angiopoietins / Q000378:metabolism; D000818:Animals; D049109:Cell Proliferation; D003331:Coronary Vessels / Q000503:physiopathology*; D004195:Disease Models, Animal; D004452:Echocardiography / Q000379:methods; D005786:Gene Expression Regulation; D006333:Heart Failure; D007037:Hypothyroidism / Q000378:metabolism; D008856:Microscopy, Fluorescence / Q000379:methods; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D009206:Myocardium / Q000378:metabolism; D010641:Phenotype; D051381:Rats; D013963:Thyroid Hormones / Q000378:metabolism*; D013965:Thyroidectomy / Q000379:methods; D013997:Time Factors; D014284:Triiodothyronine / Q000378:metabolism*; D014655:Vascular Resistance
chemical_list: D042682:Angiopoietins; D013963:Thyroid Hormones; D014284:Triiodothyronine