Electron Probe Microanalysis of Skeletal Muscle

Abstract

X-ray microanalysis using the analytical electron microscope (EMMA 4) was performed on resting frog sartorius muscles fixed by the pyroantimonate technique. Calcium was the main element of interest analyzed. Pretreatment was with ethyleneglycoltetraacetate to chelate calcium and with Tris chloride to replace sodium. Osmium-fixed controls were also analyzed. Both crystal-diffracting and energy-dispersive analyzers were employed, the former for accurate quantitation of calcium content and the latter for qualitative assessment of other elements present. Significant concentrations of calcium occurred in the dense parts of the nucleus, the triads, the thin filaments and the sarcolemma. The amount of calcium was greatly decreased by ethyleneglycoltetraacetate pretreatment and slightly increased by sodium removal. After osmium fixation alone, little calcium was detected with no localization. frem the Joint Research Fund of the Hebrew University-Hadassah Medical School and by the Tenovus Organization.

Sarcoplasmic Reticulum and Intracellular Calcium Localization at Rest and during Contraction in <i>Mytilus</i> Smooth Muscle

“…Recently, essentially similar results for the components of pyroantimonate precipitate were reported using electron probe microanalysis in frog skeletal muscle (YAROM and CHANDLER, 1974) and in cell nuclei (MIZUHIRA, 1973;MIZUHIRA and YOTSUMOTO, 1973). The conclusion that the pyroantimonate technique is appropriate to detect Ca is also supported by chemical evaluation of this technique (KLEIN et al, 1972;GARFIELD et al, 1972).…”

Ultrastructure of Heart Muscle

“…The structural complexes of junctional SR, junctional processes and plasmalemma in both cardiac and skeletal muscle are called "couplings" (10) and their consistent occurrence in most muscles has led to the tempting assumption that they are the anatomical sites at which the action potential is translated into calcium release for contraction. Indeed, calcium movements toward the Z line (where most couplings are located during relaxation), and toward the A band during contraction have been intimated by several kinds of experiments (34,35). Nevertheless, the direct demonstration of Ca2+ release from junctional SR has not been accomplished as yet, and although the free and junctional SR are clearly Ca2+ sinks, it does not necessarily follow that Ca2+ is released for contraction from either or both.…”

Meat Tenderization: Possible Causes and Mechanisms. A Review.

“…In this region of the I-band, myofibrils are known to contain transversal cytoskeletal structures called N-lines (Locker and Leet 1976;Locker 1984). It has long been established, by use of the pyroantimonate technique which allows intracellular localization of calcium ions, that, in striated muscles, N,-line is a site of intracellular calcium accumulation (Yarom and Meiri 1971;Yarom and Chandler 1974). Unexpextedly, this highly concentrated calcium has received very little attention and nothing is known so far about either its possible physiological function or the nature of linkage between this cation and N,-lines.…”