Liya Du, Jeffrey Rodgers, Nazli Gharraee, Olivia Gary, Tarek Shazly, John F Eberth, Susan M Lessner
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引用次数: 0
Abstract
Endothelial dysfunction, defined as a reduction in the bioavailability of nitric oxide (NO), is a risk factor for the occurrence and progression of various vascular diseases. This study investigates the effect of endothelial dysfunction on age-related changes in aortic extracellular matrix (ECM) microstructure and the relationship between microstructural adaptation and the mechanical response. Here, we used groups of NOS3 knockout (KO), NOS3 heterozygotes (Het), and wild-type (WT) B6 mice (controls) to study changes in hemodynamic parameters, collagen fiber organization, and both active and passive aortic mechanics using biaxial pressure myography over a time course from 1.5 to 12 mo. Our results show that homeostatic levels of passive circumferential stress and stretch were preserved in KO mice by remodeling adventitial collagen fibers toward a more predominantly circumferential direction with age, rather than by increased fibrosis, in response to hypertension induced by endothelial dysfunction. However, passive aortic stiffness in KO mice was significantly increased owing to geometrical changes, including significant increases in wall thickness and decreases in inner diameter, and by ECM microstructural reorganization, during this maladaptive vascular remodeling. Furthermore, long-term NO deficiency significantly increased smooth muscle cell (SMC) contractility initially, but this effect was attenuated with age. These findings improve our understanding of microstructural and mechanical changes during the maladaptive vascular remodeling process, demonstrating a role for adventitial collagen fiber reorientation in the response to hypertension.NEW & NOTEWORTHY Endothelial dysfunction facilitates the reorganization of collagen fibers toward a more predominantly circumferential orientation with age, consequently promoting homeostatic normalization of passive circumferential stress and stretch in the vessel subjected to hypertension.
期刊介绍:
The American Journal of Physiology-Heart and Circulatory Physiology publishes original investigations, reviews and perspectives on the physiology of the heart, vasculature, and lymphatics. These articles include experimental and theoretical studies of cardiovascular function at all levels of organization ranging from the intact and integrative animal and organ function to the cellular, subcellular, and molecular levels. The journal embraces new descriptions of these functions and their control systems, as well as their basis in biochemistry, biophysics, genetics, and cell biology. Preference is given to research that provides significant new mechanistic physiological insights that determine the performance of the normal and abnormal heart and circulation.