Growth and differentiation of chicken embryo muscle cell cultures derived from fast- and slow-growing lines. Intrinsic differences in growth characteristics and insulin response.

Primary myogenic cell cultures derived from 12-day embryos of genetically fast-growing chickens (fast cultures) and slow-growing chickens (slow cultures) were grown under identical conditions to examine differences in growth and differentiation at the cellular level. The two types of cultures exhibited significant (P less than 0.01) differences in proliferation, protein accumulation, response to the addition of insulin to the culture medium and the amount of insulin bound per nucleus. The fast cultures exhibited a larger number of both total nuclei and fused nuclei at 48, 72 and 96 h in culture, accumulated more protein per nucleus at 24, 48 and 72 h in culture and demonstrated a greater response to the addition of insulin to the culture medium, as reflected by increased fusion rate and protein accumulation at 24 h in culture. Maximal response to insulin in both types of cultures was obtained at 24 h to added insulin concentrations of 10(-10)-10(-9) M. Slow cultures bound more [125I]-insulin than fast cultures at 24 h in culture. These experiments suggest that different muscle growth potentials in animals of the same species are at least partly due to intrinsic cellular differences in the myogenic cells that give rise to adult muscle tissue.