Thyroid Hormone Promotes Remodeling of Coronary Resistance Vessels

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)

Association of total and free testosterone with cardiovascular disease in a nationally representative sample of white, black, and Mexican American men

Associations of total testosterone (T) and calculated free T with cardiovascular disease (CVD) remain poorly understood. Particularly how these associations vary according to race and ethnicity in a nationally representative sample of men. Data included 7058 men (≥20 years) from NHANES. CVD was defined as any reported diagnosis of heart failure (HF), coronary artery disease (CAD), myocardial infarction (MI), and stroke. Total T (ng/mL) was obtained among males who participated in the morning examination. Weighted multivariable-adjusted logistic regression models were conducted. We found associations of low T (OR = 1.57, 95% CI = 1.17–2.11), low calculated free T (OR = 1.53, 95% CI = 1.10–2.17), total T (Q1 vs Q5), and calculated free T (Q1 vs Q5) with CVD after adjusting for estradiol and SHBG. In disease specific analysis, low T increased prevalence of MI (OR = 1.72, 95% CI = 1.08–2.75) and HF (OR = 1.74, 95% CI = 1.08–2.82), but a continuous increment of total T reduced the prevalence of CAD. Similar inverse associations were identified among White and Mexican Americans, but not Blacks (OR = 0.93, 95% CI = 0.49–1.76). Low levels of T and calculated free T were associated with an increased prevalence of overall CVD and among White and Mexican Americans. Associations remained in the same direction with specific CVD outcomes in the overall population