Calcium regulation of skeletal myogenesis: IV. A defined culture medium permissive for myotube formation and the use of the calcium antagonist lanthanum.

Lanthanum has been used effectively in studies of calcium physiology in experiments of short duration. In experiments of longer duration, we report that solutions, such as cell culture medium, containing lanthanum (La++) undergo a decrease in pH on the time scale of hours. Presumably, the decrease in pH is a consequence of the hydrolysis of water by the solution-active La ions. We have devised a defined culture medium without serum and chick embryo extract which is permissive for myotube formation. This defined medium is also useful for studies of La as a calcium antagonist. La at concentrations of 0.1 mM reversibly inhibits myotube formation when added in conjunction with Ca++ to low-Ca++ fusion-blocked cultures.