THE CARDIAC CALCIUM PUMP.
THE CARDIAC CALCIUM PUMP.
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心脏钙泵。
DOI：
10.1073/pnas.52.6.1456
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发表时间：
1964
影响因子：
11.1
通讯作者：
M. E. Carsten
中科院分区：
文献类型：
--
作者：
M. E. Carsten
文献表明，肌管系统或内质网是肌原纤维周围的精细通道网络，2 将脉冲从细胞外膜传导到收缩装置，这种活动可能是由调节肌原纤维钙供应的能力介导的。钙的细胞内微量应用已被证明会在完整的骨骼肌纤维中产生局部挛缩。3, 4 此外，由骨骼肌内质网破碎衍生的颗粒或微粒体部分具有主动浓缩钙的能力，5-0 从而导致肌纤维“或肌原纤维松弛，12 并抑制肌原纤维 ATP 酶。13' 14 在心脏中，内质网已在电子显微照片中显示，但其含量似乎不如骨骼肌中丰富。2 来自心肌的颗粒级分制剂已部分表征了某些酶活性，5, 16 但事实证明很难获得稳定的制剂，并且钙吸收速度较低。7 事实上，钙积累机制似乎更多是线粒体的特征，而不是微粒体级分的特征。在本通讯中，从心肌中制备和部分纯化了肌管级分。将描述兔心脏，包括其一些酶特性的表征，将表明该肌管部分中的钙摄取速率不低于骨骼肌制剂中的钙摄取率，并且远高于线粒体制剂中的钙摄取率。我们建议位于肌管系统中的心脏“钙泵”控制心脏的节律性收缩和舒张。
The literature embodies suggestions' that the sarcotubular system or endoplasmic reticulum, a fine network of channels surrounding the myofibril,2 conducts impulses from the outer membrane of the cell to the contractile apparatus, an activity which may be mediated by the ability to regulate the supply of calcium to the myofibril. Intracellular microapplication of calcium has been shown to produce local contracture in the intact skeletal muscle fiber.3, 4 Furthermore, a granular or microsome fraction, derived by fragmentation of the endoplasmic reticulum of skeletal muscle has the ability to concentrate calcium actively,5-0 to bring about relaxation of muscle fibers" or of myofibrils,l2 and inhibition of myofibrillar ATPase.13' 14 In the heart, an endoplasmic reticulum has been revealed in electron micrographs, but it seems to be less abundant than in skeletal muscle.2 Preparations of granular fractions from heart muscle have been partially characterized with respect to some enzyme activities,5, 16 but it proved difficult to obtain stable preparations, and calcium uptake proceeded at a low rate. 7 Indeed it appeared that the calcium accumulating rmechanism was more a characteristic of mitochondria than of the microsome fraction.ls In the present communication the preparation and partial purification of a sarcotubular fraction from rabbit hearts will be described, including a characterization of some of its enzymatic properties. It will be shown that calcium uptake in this sarcotubular fraction proceeds at a rate not much lower than in preparations from skeletal muscle and very much higher than in mitochondrial preparations. We suggest that a cardiac "calcium pump" located in the sarcotubular system controls rhythmic contraction and relaxation of the heart.