Nerve growth factor supports growth of rat skeletal myotubes in culture

Effects of nerve growth factor (NGF) were examined on the growth of rat skeletal myotubes in culture and the expression of NaK pump activity in this preparation. We found NGF to cause an immediate increase in electrogenic NaK pump activity as determined by electrogenic component of membrane potential (Em) and ouabain-sensitive ⁸⁶Rb uptake. When given chronically, NGF was able to replace serum as an essential supplement for development of cultured myotubes. Thus, when maintained in a serum-free, basal nutrient medium (DMEM), myotubes progressively deteriorated as indicated by morphological appearance, Em and the number of [³H]ouabain binding sites compared with myotubes grown in normal, serum-supplemented growth medium (GM). In contrast, the presence of NGF in DMEM completely prevented the deterioration of these properties, their values actually exceeding those in GM. These findings demonstrate a trophic effect of NGF on bioelectric properties of neonatal mammalian muscle cells.