Effect of vitamin D and its metabolites on developing myogenic cultures

Growth, protein synthesis and expression of creatine kinase (CK) by embryonic chick myogenic cells are inhibited by vitamin D and certain of its metabolites. 25-OH cholecalciferol was most active in concentrations of 10⁻⁵–10⁻⁶ M, with cholecalciferol and ergocalciferol less active in that order. Ergosterol had no activity of this sort. Inhibition of CK was most marked on the 4th and 5th day of culture and was due to suppression of the appearance of CK-MM and MB. CK-BB was not affected and CK-MB was more affected than CK-BB. Skin fibroblasts by comparison were slightly stimulated in growth at 10⁻⁶ M and much less affected at 10⁻⁵ M than the myogenic cells. It is suggested that vitamin D has a direct effect upon the muscle cell, to cause a selective diminution in the production of certain polypeptides.