Premium
The use of lanthanum and cytochalasin B to study calcium effects on skeletal muscle differentiation in vitro
Author(s) -
Morris Glenn E.
Publication year - 1980
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041050307
Subject(s) - cytochalasin b , myogenesis , calcium , chemistry , myocyte , skeletal muscle , cytochalasin , medicine , intracellular , stimulation , endocrinology , biochemistry , biophysics , microbiology and biotechnology , biology , cell , cytoskeleton , organic chemistry
A dual effect of external Ca 2+ on creatine kinase (CPK) accumulation during myogenesis has recently been demonstrated (Morris and Cole, '79). Ca 2+ inhibits muscle‐specific CPK accumulation at intermediate (50–100 μ) concentrations compared with both lower (no added Ca 2+ ) and higher (2–3 μ) concentrations. Myoblast fusion, however, requires high Ca 2+ and is inhibited at both low and intermediate Ca 2+ levels. These effects are now investigated further by studying the effects of lanthanum ion (La 3+ ), which interferes with Ca 2+ ‐binding to membranes and Ca 2+ ‐transport, and cytochalasin B, which affects the cell membrane and prevents cell fusion without inhibiting CPK accumulation. The results show that low concentrations (10–100 μ) of La 3+ inhibit the appearance of the muscle‐specific (MM) CPK isoenzyme during myogenesis without significantly affecting cell fusion or intracellular cyclic AMP levels. Three further observations are consistent with the existence of myotube‐specific membrane‐binding sites for Ca 2+ , which are involved in the stimulation of CPK accumulation on increasing external Ca 2+ from intermediate to high concentrations. (1) CPK levels are not affected by La 3+ at 0–50 μ external Ca 2+ . (2) CPK levels in cytochalasin B treated myoblasts are hardly affected by La 3+ at any Ca 2+ concentration. (3) In cytochalasin B treated cultures, CPK levels are not increased by raising external Ca 2+ from intermediate to high levels. In contrast, the stimulation of CPK accumulation on decreasing external Ca 2+ from intermediate to very low concentrations is not affected by either La 3+ or cytochalasin B. Some alternative interpretations of the data are also considered, including direct disruption of a membrane Ca 2+ ‐binding site by cytochalasin B.