Matsumoto T, Tsuchida M, Sato M
Biomechanics Laboratory, Graduate School of Mechanical Engineering, Tohoku University, Sendai, Japan.
Am J Physiol. 1996 Oct;271(4 Pt 2):H1711-6. doi: 10.1152/ajpheart.1996.271.4.H1711.
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 degrees 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 degrees (means +/- SE, n = 14) to 153 +/- 14 degrees with the contraction and decreased to 68 +/- 9 degrees 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.
研究了考虑残余应变时平滑肌收缩对大鼠胸主动脉壁内应变分布的影响。从主动脉切下的短节段在充氧的 Krebs-Ringer 溶液（37℃）中径向切割以释放残余应变。每个节段立即张开形成一个弧。在此时以及平滑肌收缩和松弛后测量张开角度。随着收缩，角度从 97±11 度（均值±标准误，n = 14）增加到 153±14 度，随着松弛减小到 68±9 度，表明平滑肌收缩时残余应变增加。根据主动脉的张开角度和压力-直径关系计算不同压力下的壁内应变分布。在平滑肌松弛时，55 mmHg 下应变分布几乎均匀，而在平滑肌收缩时，由于残余应变增加和血管直径减小，该压力超过 200 mmHg。这些结果表明，主动脉平滑肌可能通过肌源性反应改变其收缩状态，以保持壁内应变分布均匀，抵抗血压的暂时变化，从而维持主动脉壁的机械稳态。
