APStracts 3:0280H, 1996.

Change in intramural strain distribution in rat aorta due to[f] smooth muscle contraction/relaxation. TAKEO MATSUMOTO, MASUHIRO TSUCHIDA, MASAAKI SATO

APStracts 3:0280H, 1996.

Effect of smooth muscle contraction on intramural strain distribution in rat thoracic aorta was investigated considering residual strain. Short segments sliced from the aortas were cut radially to release residual strain in an aerated Krebs Ringer solution (37 C). Each segment opened up immediately to form an arc. Opening angle was measured at this point and following smooth muscle contraction and relaxation. The angle increased from 97 11Ą (mean SEM, n=14) to 153 14Ąwith the contraction and decreased to 68 9Ą with the relaxation, indicating increase in residual strain with smooth muscle contraction. Intramural strain distribution at various pressures was calculated from the opening angle and pressure-diameter relations of the aortas. Strain distribution was almost uniform at 55 mmHg under smooth muscle relaxation, while this pressure exceeded 200 mmHg due to increase in residual strain and decrease in vessel diameter under smooth muscle contraction. These results suggest aortic smooth muscle may change its contractile state through myogenic response to keep intramural strain distribution uniform against temporary change in blood pressure, and thus maintain mechanical homeostasis in the aortic wall.

Received 22 April 1996; accepted in final form 28 June 1996.
APS Manuscript Number H353-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 July 1996