Modulation of a potassium conductance in developing skeletal muscle.
K+ conductances dominate and potentially modulate the resting potential of skeletal muscle cells. The expression and modulation of a major K+ conductance were examined during in vitro differentiation of the mouse myoblast cell line C2C12. The inwardly rectifying K+ conductance (IKi) increased from unmeasurable levels in undifferentiated myoblasts to approximately 1.56 +/- 0.51 nA (n = 17) in myoballs derived from myotubes at 5 days after induction of differentiation. The inward rectifier was subject to modulation by intracellular signals. Exposure of cytoplasm to guanosine 5'-O-(3-thiotriphosphate) during whole cell recording produced a concentration (5-100 microM)- and time (1-20 min)-dependent inhibition of the mean conductance. Elevation of intracellular free Ca2+ (> 200 nM) also inhibited IKi. These findings demonstrate a potential mechanism for modulation of the resting potential of muscle fibers via the control of skeletal muscle IKi.
Wieland
S J
SJ
Department of Anatomy, Hahnemann University, Philadelphia, Pennsylvania 19102.
Gong
Q H
QH
D000818:Animals; D002118:Calcium / Q000502:physiology; D002460:Cell Line; D004553:Electric Conductivity; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D051379:Mice; D024510:Muscle Development; D018482:Muscle, Skeletal / Q000166:cytology / Q000254:growth & development* / Q000502:physiology*; D011188:Potassium / Q000502:physiology*
D016244:Guanosine 5'-O-(3-Thiotriphosphate); D011188:Potassium; D002118:Calcium