Sarcoplasmic Reticulum of a Fast Lobster Muscle

肌浆网（SR）是肌细胞内一个扁平的、卷曲的麻袋，它控制钙离子的运动，从而调节肌肉的收缩。直接研究这种膜袋的性质一直很困难，因为它很小，在肌肉细胞内难以接近，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龙虾肌肉的机械剥皮制备方法，即第二天线的遥控器，它含有大量的SR（其体积的70%）来控制其快速收缩。这种制备可以用现代电生理学技术进行研究。可以直接记录其膜电位，并测量其膜上单个离子通道的性质。本研究的目的是对SR隔室的电特性进行系统研究，强调可能参与控制远端肌快速收缩的特性。以下特征将被研究：负责SR静息电位的离子以及已知影响兴奋-收缩耦合的钙离子、氯离子、咖啡因和普鲁卡因的作用。将研究SR中发现的两种不同类型的钙通道，并寻找调节其行为的药物。将测量SR室的电阻和电容。这项研究具有很大的生物学意义。尽管多年来人们已经知道肌浆网（SR）通过调节细胞内钙的水平来控制肌肉收缩，但这将是第一次直接测量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肌肉收缩控制的一般机制提供重要的线索。

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.