Calcium‐Activated Muscle from Hypertrophied Rabbit Hearts: Mechanical and Correlated Biochemical Changes
Calcium‐Activated Muscle from Hypertrophied Rabbit Hearts: Mechanical and Correlated Biochemical Changes
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肥大兔心脏的钙激活肌肉：机械和相关的生化变化
DOI：
10.1161/01.res.44.2.279
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发表时间：
1979
影响因子：
20.1
通讯作者：
Norman Axpert
中科院分区：
文献类型：
--
作者：
D. Maughan;E. Low;R. Litten;J. Brayden;Norman Axpert
采用化学剥离的脑室标本来研究交叉桥动力学改变对与心肌肥厚相关的缩短率降低的贡献。持续的肺收缩造成肥大。用非离子洗涤剂Brij-58处理正常和肥厚的兔右室多细胞束，并用含钙溶液直接激活。在等长条件下，从对照(C)心脏获得的束与从肥大(H)心脏获得的束在硬度或对Ca~(2+)的反应上没有显著差异。平均激活范围约为10−6~10−4 M Ca，其中5×10−6 M Ca~(2+)激活半峰。H束的等长张力Po(4.1±1.8g/ml1，10-4M Ca~(2+)，2 2±1°C)与C束无显著差异。相反，H束的等张缩短速率(从P o到给定载荷的阻尼式释放后)显著低于C束。从Hill双曲方程的线性化形式外推的缩短Vo的平均卸载速度，C束为1.87肌长/秒，H束为1.24肌长/秒，减少了34%。在用于机械实验的脑室中也进行了化学研究。Ca~(2+)和肌动蛋白刺激的H-肌球蛋白ATPase活性较C值显著降低(分别为39%和33%)，而(K+)EDTA刺激的ATPase活性无明显差异。我们认为，这些心脏的H束缩短速度降低34%，肌球蛋白的钙激活和肌动蛋白激活的ATPase活性降低，这可能反映了缩短过程中肌球蛋白跨桥循环的速度降低。中国保监会第44号决议：279-287,1979
A chemically skinned ventricular preparation was used to investigate the contribution of altered crossbridge kinetics to the depressed rate of shortening associated with cardiac hypertrophy. Hypertrophy was produced by sustained pulmonary constriction. Multicellular bundles from control and hypertrophied right ventricles of rabbit hearts were treated with Brij-58 (a non-ionic detergent) and directly activated with solutions containing calcium. Bundles obtained from control (C) hearts did not differ significantly from bundles taken from hypertrophied (H) hearts in stiffness or in response to Ca2+ under isometric conditions. Mean activation range was approximately 10−6 to 10−4 M Ca, with half-maximal activation at 5 x 10−6 M Ca2+. Isometric tension P o of H bundles (4.1 ± 1.8 g/mm 1, at 10-4 M Ca2+, 22 ± 1°C) was not significantly different from that of C bundles. In contrast, the isotonic shortening rate (following a damped release from P o to a given load) of H bundles was significantly lower than that of C bundles. Mean unloaded velocity of shortening Vo, extrapolated from the linearized form of the Hill hyperbolic equation, was 1.87 muscle lengths/sec for C bundles and 1.24 muscle lengths/sec for H bundles, a 34% reduction. Chemical studies also were carried out in ventricles used for the mechanical experiments. The Ca2+- and actin-stimulated ATPase activities of H myosin were significantly depressed (by 39% and 33%, respectively) compared with the C values, whereas there was no observed difference in (K+)EDTA-stimulated ATPase activity. We conclude that the 34% reduction in shortening velocity of H bundles as well as the depression in Ca 2+- and actin-activated ATPase activity of myosin from these same hearts probably reflect a decrease in the rate of myosin crossbridge cycling during shortening. Circ Res 44: 279-287, 1979