Tension responses of sheep aorta to simultaneous decreases in phosphocreatine, inorganic phosphate and ATP.
Tension responses of sheep aorta to simultaneous decreases in phosphocreatine, inorganic phosphate and ATP.
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绵羊主动脉对磷酸肌酸、无机磷酸盐和 ATP 同时降低的张力反应。
DOI：
10.1113/jphysiol.1992.sp019410
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Kushmerick,MJ
中科院分区：
文献类型：
--
作者：
Hardin,CD;Wiseman,RW;Kushmerick,MJ
1. 研究了灌流介质中包含不同基质时绵羊主动脉的张力反应。无论培养基中是否存在 5 mM 葡萄糖，张力发展的程度都相似。然而，在没有葡萄糖的情况下，紧张发展的速度更快。 2. 当培养基中存在 5 mM 2-脱氧葡萄糖 (2DG) 时，张力产生的幅度是不存在外源底物时的 1.6 倍。使用 2DG 进行第二次连续收缩产生的张力是不存在外源底物时的 1.25 倍。在存在 2DG 的情况下，第一次收缩期间的张力发展速率与不存在基质的情况相似。然而，在存在 2DG 的情况下，第二次收缩的张力发展速度显着增加。 3. 31P核磁共振（NMR）光谱显示，在静息状态下，在2DG存在的情况下，无机磷酸盐（P(i)）和磷酸肌酸（PCr）同时减少，同时2-脱氧葡萄糖-6-磷酸盐积累。在收缩-舒张循环期间，在 2DG 存在的情况下，P(i) 和 PCr 变得不可检测，而 ATP 下降至 NMR 测定的对照值的大约 50%。在 2DG 存在的第二次收缩期间，ADP 共振的面积与 α-ATP 共振的面积相似。 4. 2DG 给药期间张力产生强度的增加与 P(i) 水平的降低相关。在存在 2DG 的情况下，收缩舒张的速率比存在葡萄糖或不存在外源底物的情况下慢。这些结果与 P(i) 在释放低能量需求下维持收缩的“闩桥”状态中的作用一致。 5. 在存在 2DG 的情况下，收缩过程中等长张力产生的增加似乎与 P(i) 水平的降低有关。在 2DG 存在的情况下，PCr 和 ATP 的减少程度与缺氧期间相似，但不会发生力抑制。在这些研究中，2DG 给药时报告的 ATP 和 PCr 水平较低，并没有大力限制收缩装置。
1. Tension responses of sheep aortae were investigated when different substrates were included in the superfusing medium. The magnitude of tension development was similar whether or not 5 mM glucose was present in the medium. However, the rate of tension development was greater in the absence of glucose. 2. When 5 mM 2‐deoxyglucose (2DG) was present in the medium, the magnitude of tension generation was 1.6 times that in the absence of exogenous substrate. A second sequential contraction with 2DG generated tension 1.25 times that in the absence of exogenous substrate. The rate of tension development during the first contraction in the presence of 2DG was similar to that in the absence of substrate. However, the second contraction in the presence of 2DG had a substantially increased rate of tension development. 3. 31P nuclear magnetic resonance (NMR) spectroscopy revealed that, at resting tone, in the presence of 2DG, inorganic phosphate (P(i)) and phosphocreatine (PCr) simultaneously decrease while 2‐deoxyglucose‐6‐phosphate accumulates. During contraction‐relaxation cycles, in the presence of 2DG, P(i) and PCr become undetectable while ATP declines to approximately 50% of control values as determined by NMR. During the second contraction in the presence of 2DG, the area of the ADP resonance was similar to that of the alpha‐ATP resonance. 4. The increase in the magnitude of tension generation, during 2DG administration, correlated with a decrease in P(i) levels. The rate of relaxation from a contraction, in the presence of 2DG, was slower than in the presence of glucose or in the absence of exogenous substrate. These results are consistent with the role of P(i) in the release of the proposed ‘latch‐bridge’ state of maintained contraction at low energy demand. 5. The increase in isometric tension generation during contraction in the presence of 2DG appears to be related to the decreased levels of P(i). In the presence of 2DG, the reduction of PCr and of ATP occur to a similar extent to that during hypoxia, yet no inhibition of force takes place. The low levels of ATP and PCr reported with 2DG administration in these studies do not energetically limit the contractile apparatus.
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DOI：
--
发表时间：
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期刊：
Acta Physiologica Scandinavica
影响因子：
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DOI：
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DOI：
10.1152/ajpheart.1989.257.2.h597
发表时间：
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期刊：
The American journal of physiology
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