Arterial remodeling in chronic sinoaortic-denervated rats

The spontaneous variation of blood pressure is defined as "blood pressure v ariability" (BPV). The chronic sinoaortic-denervated (SAD) rat is a model o f high BPV without sustained hypertension. Little is known about vascular r emodeling in this model. In the present study, we examined blood pressure, vascular remodeling, and aortic angiotensin II concentration in chronic SAD rats in separate experiments. In experiment 1, intra-arterial blood pressu re was continuously recorded in conscious unrestrained rats. The 16-week SA D rats had a significant increase in BPV and no change in the mean level of blood pressure over a 24-h period. In experiment 2, we measured structural changes of seven kinds of arteries by histologic method and computer image analysis and functional changes of thoracic aortas by isolated artery prep aration. Structural remodeling after 16-week sinoaortic denervation was cha racterized by increase in wall thickness, wall area, and ratio of wall thic kness to internal diameter, with different changes in internal diameter and external diameter in different arteries, indicating that arterial structur al remodeling expresses itself mainly as vascular growth. This vascular gro wth might be caused by medial smooth muscle cell growth and collagen accumu lation. Aortic contraction induced by norepinephrine was potentiated, where as aortic relaxation induced by acetylcholine was attenuated after sinoaort ic denervation. In experiment 3, plasma and aortic angiotensin II concentra tions were determined by radioimmunoassay. The former remained unchanged, w hereas the latter was significantly increased in 10-week SAD rats. It is co ncluded that in rats chronic sinoaortic denervation can produce vascular re modeling that might be related to increased BPV and an activated tissue ren in-angiotensin system.