Smooth Endoplasmic Reticulum in Rat Hepatocytes during Glycogen Deposition and Depletion

Abstract

Publisher Summary This chapter discusses the role of smooth endoplasmic reticulum (SER) in hepatic glycogen metabolism. Data are reviewed from several types of experiments which allowed study of the participation of SER in glycogenesis and glycogenolysis. SER functions in both synthesis and degradation of hepatic glycogen. The development of SER follows a cyclic pattern: proliferation of the organelle occurs during early stages of glycogen deposition and remains associated with glycogen particles throughout all stages of deposition of the carbohydrate until high or maximum quantities of glycogen are accumulated by the cell. At this point SER decreases to very low levels in hepatocytes. During depletion of glycogen, SER again proliferates and shows a close relationship to the remaining glycogen particles in hepatocytes. An abundance of SER is present in hepatocytes throughout all stages of glycogen depletion until the cell is devoid of glycogen granules. At this point SER decreases to low values but nevertheless is present in small quantities. Much attention should be given in future work to obtaining pure SER membranes from livers of rats under precisely controlled metabolic conditions and assaying these membranes for various enzymes involved in glycogen metabolism.