Initial uncoordinated expression of three types of voltage-gated currents in cultured Xenopus myocytes.
The expression of three types of voltage-gated ionic currents, namely the Na+ inward current, K+ outward rectifier current and K+ inward rectifier current, was examined in cultured developing Xenopus myocytes. In the population of myocytes, the Na+ inward current and K+ outward rectifier current appeared at around 32 h after fertilization (stage 27) and gradually increased during the period of observation, up to more than 44 h after fertilization (stage 33/34). The developmental time course of these two types of currents was similar. However, during the transition period individual myocytes did not necessarily express these two types of currents in a coordinated fashion. Some myocytes had a large Na+ inward current and small K+ outward rectifier current or vice versa. The K+ inward rectifier current was observed in some cells earlier than stage 27 and also gradually increased during the observation period. The initial expression of this current was not correlated with the K+ outward rectifier current or with the Na+ inward current.
Kidokoro
Y
Y
Jerry Lewis Neuromuscular Research Center, Department of Physiology, UCLA School of Medicine 90024.
D000818:Animals; D002478:Cells, Cultured; D004594:Electrophysiology; D015640:Ion Channel Gating; D007473:Ion Channels / Q000502:physiology*; D008564:Membrane Potentials; D009132:Muscles / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D014981:Xenopus / Q000196:embryology
D007473:Ion Channels