Age-Related Changes of Arterial Mechanical Properties in Rats: Analysis Using Exponentially Tapered T-Tube Model

• Published in: The journals of gerontology. Series A, Biological sciences and medical sciences Biological sciences and medical sciences, 1998-07, Vol.53A (4), p.B274-B280
• Main Authors: Chang, Kuo-Chu, Tsai, Yuan-Feen, Chow, Chai-Yee, Peng, Ying-I, Chen, Tong-J
• Format: Article
• Language: English
• Subjects: Age; Aging - physiology; Analysis of Variance; Animals; Aorta - physiology; Blood Pressure - physiology; Blood vessels; Gerontology; Heart Rate - physiology; Male; Models, Cardiovascular; Pulsatile Flow; Rats; Rodents; Vascular Resistance - physiology; Vasodilation - physiology
• ISSN: 1079-5006; 1758-535X
• DOI: 10.1093/gerona/53A.4.B274

This study was designed to explore the changes of mechanical properties in the rat's arterial system at different agesby using the exponentially tapered T-tube model. Long-Evans male rats at the ages of 6, 12, and 18 months wereanesthetized and thoractomized. Rats at the ages of 6, 12, and 18 months were individually referred to as young,adult, and middle-aged rats. The pulsatile pressure and flow signals in the ascending aorta were measured by ahigh-fidelity pressure sensor and electromagnetic flow probe, respectively. Model parameters, such as aortic characteristicimpedance, vascular tapering index, wave transit time, and arterial load compliance, were inferred from theaortic pressure and flow signals to describe the pulsatile nature of blood flows in the vasculature. The static hemodynamiccondition in those animals with different ages was characterized by (i) no change in cardiac output and (ii)a decrease in heart rate, arterial blood pressure, as well as total peripheral resistance. As for the pulsatile nature ofthe arterial system, the wave transit time remained unaltered, indicating there was no change in the aorta's distensibilityof rats at those three different ages. The arterial load compliance, which describes the buffering nature of ahollow vessel, also remained unchanged. On the contrary, there was a significant fall in aortic characteristicimpedance in those age-related rats. The decline of aortic characteristic impedance without a significant change inarterial distensibility suggests that lumen growth of the aorta and large arteries may occur in rats up to middle age.