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RESEARCH PAPERS

Mechanical and Dimensional Adaptation of Rat Aorta to Hypertension

[+] Author and Article Information
T. Matsumoto

Department of Mechatronics and Precision Engineering, Tohoku University, Sendai 980, Japan

K. Hayashi

Department of Mechanical Engineering, Osaka University, Toyonaka, Osaka 560, Japan

J Biomech Eng 116(3), 278-283 (Aug 01, 1994) (6 pages) doi:10.1115/1.2895731 History: Received February 22, 1991; Revised August 27, 1993; Online March 17, 2008

Abstract

To investigate mechanisms of the mechanical adaptation of soft biological tissues to load, effects of hypertension on the mechanical properties and wall dimensions of thoracic aortas were studied in rats. Goldblatt hypertension was induced in male Wistar rats aged 8 to 9 weeks by constricting their left renal arteries. Two, 4, 8, or 16 weeks after the operation, thoracic aortas were excised and used to determine static pressure-diameter relations and wall dimensions. Wall thickness correlated significantly with the systolic blood pressure before sacrifice, Psys, at each period. The aortic hoop stress became almost constant at all Psys 2 weeks after the operation. On the other hand, the stress calculated for 100 and 200 mmHg correlated negatively with Psys. The incremental elastic modulus of the wall at Psys had a significant correlation with Psys having a positive slope at each period, although the correlation disappeared at 16 weeks after the operation. These results imply that: 1) thickness of the aortic wall increases very rapidly in response to hypertension; 2) wall stress developed by the in-situ blood pressure is kept constant at a normal level irrespective of hypertension; 3) elastic modulus of the wall of the hypertensive rats at the in-situ blood pressure becomes equal to the normal value after relatively long period of time; 4) in response to the alteration of the applied force, dimensional change appears much earlier than the change in the elastic properties.

Copyright © 1994 by The American Society of Mechanical Engineers
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