Dystrophic Muscle Function Research Articles

Norepinephrine-induced membrane responses in normal and dystrophic hamster skeletal muscle.

AbstractTwo skeletal muscle membrane responses were examined to evaluate the role of membrane alterations in dystrophic muscle function. These responses—norepinephrine-evoked changes in membrane conductance and potential—have been suggested to be associated with nonshivering metabolic pathways independent of contractile events. Norepinephrine (at concentrations ranging from 50-300 μg/kg) and/or saline was injected intravenously into anesthetized control hamsters and Bar Harbor 14.6 cardiomyopathic hamsters (2-3 months old). Glass microelectrodes were used to measure the intracellular potentials and membrane resistances of gracilis anticus cells. In the normal hamsters, norepinephrine administration was followed by a small, but significant membrane depolarization (X = 6.7 ± 1.4 mV) and a decrease in membrane resistance (X = 1.0 ± 0.1 mΩ). In contrast, saline had little or no effect on these parameters. The voltage and resistance changes observed in dystrophic muscle cells were in the same direction as thos...