Elements in muscle measured in vivo and in vitro with X‐ray spectrometry

Calcium, iron, copper, and zinc concentrations in muscle were measured in vivo by x‐ray spectrometry (XRS). The undersurface of the tongue was examined in cardiomyopathic and in normal hamsters. Values were compared to in‐vitro analyses of various muscles from the same groups of animals using XRS and chemical analysis. Blood tests as well as histologic and histometric examinations were also performed. The correlated results show that XRS is a relatively sensitive and practical method for measuring chemical elements in muscle, and that it could be developed into a useful clinical test in certain neuromuscular and myocardial diseases. An interesting incidental finding was that, though all the examined muscles of myopathic animals had pathologic changes, only the tongue and myocardium, which are composed exclusively of red fibers, showed excessive calcium accumulation. This suggests either that the basic genetic aberration is not directly related to the oxidative metabolism, or that white muscles have a more efficient system for dealing with calcium overload.