Metabolic alterations induced in cultured skeletal muscle by stretch-relaxation activity.

Avian pectoralis muscle cells differentiated in vitro are mechanically stimulated by repetitive stretch-relaxations of the cell's substratum. Their metabolic response to mechanical activity is determined by measuring rates of [3H]deoxy-D-glucose uptake and lactate efflux. These two metabolic parameters show a similar biphasic response to mechanical stimulation. During the first 4-6 h of activity, [3H]deoxy-D-glucose uptake and lactate efflux increase 34 and 26%, respectively; at 8 and 24 h of activity, [3H]deoxy-D-glucose uptake and lactate efflux are no longer elevated relative to control values. With continued activity beyond 24 h, their rates are again significantly elevated (150 and 93% by 48 h, respectively). The long-term increases in [3H]deoxy-D-glucose uptake and lactate efflux occur independently of medium growth factors. Protein synthesis is required for the short-term increase in [3H]deoxy-D-glucose uptake, but muscle electrical activity is not required for either short- or long-term increases in [3H]deoxy-D-glucose uptake because both occur in the presence of tetrodotoxin. This new model system allows for the analysis of mechanically induced metabolic alterations in aneural skeletal muscle cells under the defined conditions of tissue culture.