Electron Micoscopic Observation on Coupling of Sarcoplasmic Reticulum with the Intercalated Disk in Myocardial Cells of Rat / 第三军医大学学报

ABSTRACT

The ultrastructure of the relationship between the sarcoplasmic (SR) and the intercalated disk in the atrial myocardial cells of the heart is studied. The results reveal a coupling exists between the SR and the unspecializsd sarcolem-ma of the intercalated disk. In order to differentiate it from a general peripheral coupling it is called intercalated disk coupling. It possesses 3 morphological features of the peripheral and interior couplings, i. e., the cytoplasmic gap in coupling region is about 11-18 nm in width; the jnctional processes or junc-tional feet are located in the cytoplasmic gap; and the SR contains electronic dense material in its lumen. In the coupling region the RS membranes are not only coupling with the unspecialized membrane of the intercalated disk but also closely apposed to the external membrane of mitochondria. In addition, the gap junction-sarcoplasmic reticulum couplings are formed between the cardial gap junction and the SR. Its ultrastructural characteristics are the same as the cardial couplings. The functional significance of the couplings of the SR with the intercalated disk is discussed.