TUBULAR AGGREGATES INDUCED BY ANOXIA IN ISOLATED RAT SKELETAL-MUSCLE

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  • 1 January 1977
    • journal article
    • research article
    • Vol. 37  (3) , 223-228
Abstract
The fast-twitch extensor digitorum longus and the slow-twitch soleus muscles of the rat were incubated for 1-6 h in vitro in an O2-free medium or a medium containing KCN. Within 3 h of incubation, characteristic structural alterations of the sarcoplasmic reticulum [SR] were observed in extensor digitorum longus muscle fibers. Concomitant with the disruption of the normal sarcotubular organization there was a selective clustering of SR elements with formation of tubular aggregates similar to those observed in human muscle under various pathologic conditions. The aggregates increased in size by apposition of new tubules at the periphery and acquired a regular hexagonal arrangement. Double-walled tubules, apparently derived from folding of SR tubules, were also contained in the aggregates. Electron-opaque material was seen connecting adjacent tubules. This material was derived from the Z-bands which appeared largely extraced since early stages of anoxic injury. Tubular aggregates were not seen in soleus muscle fibers incubated under the same conditions in vitro. Tubular aggregates can be formed by simple rearrangement of the SR without proliferation of new sarcotubular elements.