Electrophysiologic properties of aneurally cultured muscle from patients with myotonic muscular atrophy.

Electrophysiologic studies were performed on aneurally cultured human muscle cells from seven patients with myotonic muscular atrophy and seven controls. There was no significant difference in resting membrane potential. When the cells were hyperpolarized to -80 mV, there was no significant difference in effective membrane resistance, effective membrane capacitance, normalized membrane conductance, membrane threshold, action potential amplitude, or maximum rate of rise of the action potential. Repetitive discharges were elicited by anodal-break excitation in a few cells from each group. We found no evidence that cultured myotonic atrophy muscle cells are electrically different from control cells.