Journal
AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY
Volume 289, Issue 2, Pages H845-H851Publisher
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajpheart.00134.2005
Keywords
extracellular matrix; type 2 diabetes; arterial compliance; insulin resistance; transforming growth factor-beta
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Accumulating clinical evidence indicates increased aortic stiffness, an independent risk factor for cardiovascular and all-cause mortality, in type 2 diabetic and glucose-intolerant individuals. The present study sought to determine whether increased mechanical stiffness, an altered extracellular matrix, and a profibrotic gene expression profile could be observed in the aorta of the insulin-resistant Zucker fa/fa rat. Mechanical testing of Zucker fa/fa aortas showed increased vascular stiffness in longitudinal and circumferential directions compared with Zucker lean controls. Unequal elevations in developed strain favoring the longitudinal direction resulted in a loss of anisotropy. Real-time quantitative PCR and immunohistochemistry revealed increased expression of fibronectin and collagen IV alpha(3) in the Zucker fa/fa aorta. In addition, expression of transforming growth factor-beta and several Smad proteins was increased in vessels from insulin-resistant animals. In rat vascular smooth muscle cells, 12-18 h of exposure to insulin (100 nmol/l) enhanced transforming growth factor-beta 1 mRNA expression, implicating a role for hyperinsulinemia in vascular stiffness. Thus there is mechanical, structural, and molecular evidence of arteriosclerosis in the Zucker fa/fa rat at the glucose-intolerant, hyperinsulinemic stage.
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