Sarcoplasmic Reticulum of a Fast Lobster Muscle

肌浆网(SR)是肌细胞内的一个扁平、卷曲的袋子，控制着钙离子的运动，从而调节肌肉的收缩。直接研究这种膜袋的特性一直很困难，因为它太小了，而且无法进入肌肉细胞，但新技术已经解决了这两个问题。艾森伯格博士开发了一种特殊的龙虾肌肉的机械剥皮制剂，这种肌肉是第二根天线的遥控器，含有大量的SR(其体积的70%)来控制其非常迅速的收缩。这种制剂可以用现代电生理学技术进行研究。它的膜电位可以直接记录下来，并可以测量其膜上单个离子通道的性质。这项研究的目的是系统地研究SR室的电特性，强调可能参与控制远端肌肉快速收缩的特性。将研究以下特征：负责SR静息电位的离子以及钙离子、氯离子、咖啡因和普鲁卡因的影响，这些都是已知的影响兴奋-收缩偶联的因素。在SR中发现的两种不同类型的钙通道将被研究，并将寻找调节其行为的药物。将测量SR隔室的电阻和电容。这项研究具有很大的生物学意义。尽管肌浆网(SR)通过调节细胞内钙离子水平来控制肌肉收缩已知多年，但这将是第一次在任何制剂中直接测量SR膜及其单个离子通道的电学性质。这种特殊的、快速收缩的龙虾肌肉应该为控制肌肉收缩的一般机制提供重要线索。

The sarcoplasmic reticulum (SR) is a flattened, convoluted sack within muscle cells that controls the movement of calcium ions, and thus regulates the contraction of muscle. It has been hard to study the properties of this membranous sack directly because it is so small and inaccessible within the muscle cell, but new techniques have removed both problems. Dr. Eisenberg has developed a mechanically skinned preparation of a specialized lobster muscle, the remotor of the second antenna, that contains a large amount of SR (70% of its volume) to control its very rapid contractions. This preparation can be studied with modern techniques of electrophysiology. Its membrane potential can be recorded directly, and the properties of the individual ion channels of its membrane can be measured. The objective of this research is a systematic study of the electrical properties of the SR compartment, emphasizing the properties likely to be involved in the control of the rapid contraction of the remotor muscle. The following features will be studied: the ions responsible for the resting potential of the SR and the effects of calcium ions, chloride ions, caffeine, and procaine which are known to affect excitation-contraction coupling. The two different types of calcium channel found in the SR will be studied, and agents that modulate their behavior will be sought. The resistance and capacitance of the SR compartment will be measured. This research is of great biological interest. Although it has been known for many years that the sarcoplasmic reticulum (SR) controls muscle contraction by regulating the levels of intracellular calcium, this will be the first time that direct measurements of the electrical properties of the SR membrane and its individual ion channels have been made in any preparation. This specialized, rapidly contracting lobster muscle should provide important clues to the general mechanisms of control of muscle contraction.