Effect of smooth muscle contraction on intramural strain distribution in rat thoracic aorta was investigated with residual strain considered. 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 after smooth muscle contraction and relaxation. The angle increased from 97 ± 11° (means ± SE, n = 14) to 153 ± 14° with the contraction and decreased to 68 ± 9° 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, whereas this pressure exceeded 200 mmHg because of the 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.
|ジャーナル||American Journal of Physiology - Heart and Circulatory Physiology|
|出版ステータス||Published - 1996 10月 1|
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