The uptake of 99mtechnetium diphosphonate into degenerating and regenerating muscle. A correlative histological and biochemical study.

The uptake of 99mTc-methylene diphosphonate into rat skeletal muscle has been studied. Uptake did not occur in normal or denervated muscles. Muscles damaged by exposure to the myotoxin notexin did accumulate label. The toxin causes a severe inflammatory, necrotising myopathy and regeneration normally begins 2-3 days after toxin administration. The uptake of label was maximal at 12-24 h, at which time muscle wet weight and cellular infiltration were also maximal. Label was found in the muscle mitochondria, the invading inflammatory cells and the oedema fluid. Regenerating muscles did not accumulate label. The uptake of label was positively correlated with total muscle calcium up to 24 h after the onset of necrosis, but it was suggested that the changes in the two parameters are not causally related.