X-ray microanalysis of calcium in ischemic skeletal muscle cells.

Tissue sections of both transiently and persistently ischemic musculus latissimus dorsi of rabbits show degenerated and necrotic cells in varying degrees. Degenerated mitochondria appearing in the cells contain moderate electron-dense fluffy intramatrical deposits. However, only in the transient ischemia sample can other two kinds of electron-dense granules be seen between myofibrils. According to their ultrastructure, size and distribution, the larger granules are considered the degenerated mitochondria, and the smaller ones the degenerated sarcoplasmic reticulum. X-ray microanalysis proves that these two kinds of granules contain high concentration of calcium, while the fluffy deposits contain little calcium. The findings suggest that the calcium deposits in the degenerated and necrotic cell seen under light microscope occur in mitochondria and sarcoplasmic reticulum of the transiently ischemic muscle cell. The conditions of calcium accumulation in ischemic muscle cells are discussed.