EFFECT OF RESIDUAL-STRESS ON TRANSMURAL SARCOMERE-LENGTH DISTRIBUTIONS IN RAT LEFT-VENTRICLE
EFFECT OF RESIDUAL-STRESS ON TRANSMURAL SARCOMERE-LENGTH DISTRIBUTIONS IN RAT LEFT-VENTRICLE
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DOI：
10.1152/ajpheart.1993.264.4.h1048
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发表时间：
1993-04-01
影响因子：
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通讯作者：
MCCULLOCH, AD
中科院分区：
文献类型：
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作者：
RODRIGUEZ, EK;OMENS, JH;MCCULLOCH, AD
先前已经表明，无负载的被动左心室 (LV) 壁中的心肌并非没有压力。为了评估心室壁残余应力的功能意义，我们比较了固定在无负荷（残余应力）和无应力状态下的大鼠左心室心肌标本中肌节长度（SL）的跨壁分布。当从新鲜捕获的大鼠心脏的赤道区域切下的横截面环被径向切割以释放残余应力时，它突然张开成平均张角为 45 +/- 15 度 (SD) (n = 8) 的弧形。在戊二醛中浸泡固定期间，张开角度总体增加了 9.3 +/- 7.1 度 (SD)。在无应力组织切片中距游离壁 16 个等距透壁位置处测量 SL，并将其与残余应力未消除的相邻横截面环的对照测量值进行比较。无应力组织 (n = 11) 的平均 SL 为 1.84 +/- 0.05 (SD) mum，无负载组织的平均 SL 为 1.83 +/- 0.06 (SD) mum。然而，对汇总数据的协方差分析表明，跨壁分布存在显着差异（P < 0.0001）。尽管在无应力状态下 SL 在整个壁上是均匀的，平均梯度为 -0.014 +/- 0.044 (SD) mum/总壁厚，但在完整的卸载组织中，从心外膜到心内膜 SL 显着降低 (P = 0.001) [斜率 = -0.114 +/- 0.054 (SD) mum/总壁厚]。该梯度可以抵消充盈期间肌节延伸的相反梯度，从而导致舒张末期 SL 的透壁分布更均匀，从而使收缩力发展更均匀。
It has been previously shown that the myocardium in the walls of the unloaded passive left ventricle (LV) is not stress free. To assess the functional significance of residual stress in the ventricular wall, we compared the transmural distributions of sarcomere length (SL) in specimens of rat LV myocardium fixed in the unloaded (residually stressed) and stress-free states. When a cross-sectional ring cut from the equatorial region of the freshly arrested rat hearts was cut radially to relieve residual stress, it sprang open into an arc with a mean opening angle of 45 +/- 15-degrees (SD) (n = 8). During immersion fixation in glutaraldehyde, the opening angle increased 9.3 +/- 7.1-degrees (SD) overall. SLs were measured at 16 equally spaced transmural locations from the free wall in the stress-free tissue sections and were compared with control measurements from adjacent cross-sectional rings in which residual stress had not been relieved. Average SL for the stress-free tissue (n = 11) was 1.84 +/- 0.05 (SD) mum and for the unloaded tissue was 1.83 +/- 0.06 (SD) mum. However, analysis of covariance on the pooled data showed that the transmural distributions were significantly different (P < 0.0001). Whereas SL was uniform across the wall in the stress-free state with a mean gradient of -0.014 +/- 0.044 (SD) mum/total wall thickness, there was a significant decrease (P = 0.001) in SL from epicardium to endocardium in the intact unloaded tissue [slope = -0.114 +/- 0.054 (SD) mum/total wall thickness]. This gradient may offset the opposite gradient in sarcomere extension during filling thus leading to a more uniform transmural distribution of SL at end diastole and hence more uniform development of systolic force.