Post‐ischemic Calcification in Skeletal Muscle

The extent of post-ischemic calcification in skeletal muscle was studied in rats subjected to 5.5 h of ischemia followed by periods of reperfusion ranging from 30 min to 16 h. Sections from the tibialis posterior and soleus muscle were stained with alizarin red S (ARS) and were inspected with light microscopy. The number of ARS-positive cells increased during the first 5 h of reperfusion. The extent of calcification varied between fibers and the pattern of calcification appeared to be dependent on fiber type. In some fast glycogenolytic fibers (FG) central calcifications, probably representing mitochondria, were observed. In fast oxidative glycogenolytic (FOG) and slow oxidative (SO) fibers the most common pattern was an ARS-positive granulation, probably representing calcification of sarcoplasmic reticulum and/or mitochondria. The granulation was more extensive in FOG than in SO fibers. In some areas extracellular ARS-positive material was observed. In such areas, which probably represent areas of no-reflow, no calcification of muscle fibers was observed.