Different biomechanical properties of medial and adventitial layers of thoracic aorta in Wistar-Kyoto and spontaneously hypertensive rats.
OBJECTIVE
To evaluate the biomechanical properties of thoracic aorta with or without adventitia, and to determine whether there are corresponding changes with hypertension.


METHODS
Normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) at the age of 16 and 32 weeks were used. Thoracic aortic adventitial layer was mechanically separated from thoracic aorta and the adventitia-denuded artery ring was viewed as thoracic media. A load-strain curve was obtained by stretching the ring-shaped intact thoracic aorta or thoracic media with a tensile testing machine. Then, the slope of the load-stain curve at 30%-40% strains was viewed as the elastic stiffness at physiological load, whereas the slope near the breaking point was calculated as maximum stiffness. The maximum load is the load at the breaking point.


RESULTS
There was no significant difference in elastic stiffness and maximum stiffness of intact thoracic aorta between SHR and age-matched WKY. The elastic stiffness of intact thoracic aorta showed no significant difference from that of thoracic media in WKY and SHR at both ages. In contrast, both maximum stiffness and maximum load were reduced in thoracic media compared with intact thoracic aorta in SHR and WKY at both ages.


CONCLUSIONS
These results indicated that vascular adventitia contributes to maximum stiffness, but not elastic stiffness in both SHR and WKY.
Han
Wei-qing
WQ
Department of Hypertension, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, China.
Chen
Jing
J
Wu
Ling-yun
LY
Zhu
Ding-liang
DL
Gao
Ping-jin
PJ
D000818:Animals; D001013:Aorta, Thoracic / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D001794:Blood Pressure; D003238:Connective Tissue / Q000503:physiopathology*; D004548:Elasticity; D006973:Hypertension / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D013045:Species Specificity; D017540:Tunica Media / Q000503:physiopathology*
Vasc Health Risk Manag. 2010 Apr 15;6:215-28
20407629
J Hypertens. 1997 Dec;15(12 Pt 1):1415-22
9431847
J Hypertens. 1999 Apr;17(4):481-7
10404949
Hypertension. 2001 Dec 1;38(6):1416-21
11751728
Am J Physiol Regul Integr Comp Physiol. 2002 Dec;283(6):R1442-9
12388474
Life Sci. 2009 May 22;84(21-22):732-7
19268479
Am J Physiol Heart Circ Physiol. 2004 Oct;287(4):H1663-9
15371266
Hypertension. 1981 Jul-Aug;3(4):479-84
7309209
FASEB J. 2006 Jun;20(8):1245-7
16611833
J Biomech. 1984;17(11):839-47
6520132
Hypertension. 2001 Nov;38(5):1167-71
11711516
Hypertension. 2001 Oct;38(4):943-8
11641314
Atherosclerosis. 1996 Dec 20;127(2):155-65
9125305
Arterioscler Thromb Vasc Biol. 1998 Jul;18(7):1027-34
9672062
Hypertens Res. 2006 Feb;29(2):95-103
16755143
Clin Exp Pharmacol Physiol. 2009 May;36(5-6):583-8
19673944
Acta Endocrinol (Copenh). 1980 May;94(1):132-7
6247871
Matrix Biol. 2005 Oct;24(7):451-8
16095890
Pharmacol Ther. 2009 May;122(2):140-9
19285526
Arterioscler Thromb Vasc Biol. 2002 Dec 1;22(12):1962-71
12482820
Circ Res. 2005 Mar 18;96(5):583-91
15705963
Hypertension. 1997 May;29(5):1199-203
9149687
Am J Physiol Heart Circ Physiol. 2003 Oct;285(4):H1363-9
12969878
Am J Physiol Heart Circ Physiol. 2002 Jun;282(6):H2427-40
12003855
J Hypertens Suppl. 1997 Mar;15(2):S89-97
9218205
Am J Physiol Heart Circ Physiol. 2005 Jun;288(6):H2581-7
15792993
Exp Gerontol. 1981;16(1):35-9
7215478
J Clin Invest. 2007 Mar;117(3):568-75
17332884