The suppression of myogenic functions in heterokaryons formed by fusing chick myocytes to diploid rat fibroblasts.

Heterokaryons were formed by fusing differentiated chick skeletal myocytes to fibroblasts derived from skin, lung or heart cultures. The heterokaryons were analyzed for the synthesis of skeletal myosin light chains, acetylcholine receptor, total CPK activity and the ability to spontaneously fuse to form myotubes. Whereas all of the above myogenic functions were expressed in control heterokaryons formed between myocytes and myoblasts, all were extinguished in the crosses between myocytes and fibroblasts. These results confirm that the suppression of myogenic functions previously observed in cell hybrids involving fibroblastoid tumor cells also occurs in heterokaryons isolated using biochemical inhibitors between diploid fibroblasts and chick skeletal myocytes.