Abstract:
:Electrically excitable channels were expressed in Chinese hamster ovary cells using a vaccinia virus vector system. In cells expressing rat brain IIA Na+ channels only, brief pulses (< 1 ms) of depolarizing current resulted in action potentials with a prolonged (0.5-3 s) depolarizing plateau; this plateau was caused by slow and incomplete Na+ channel inactivation. In cells expressing both Na+ and Drosophila Shaker H4 transient K+ channels, there were neuron-like action potentials. In cells with appropriate Na+/K+ current ratios, maintaining stimulation produced repetitive firing over a 10-fold range of frequencies but eventually led to "lock-up" of the potential at a positive value after several seconds of stimulation. The latter effect was due primarily to slow inactivation of the K+ currents. Numerical simulations of modified Hodgkin-Huxley equations describing these currents, using parameters from voltage-clamp kinetics studied in the same cells, accounted for most features of the voltage trajectories. The present study shows that insights into the mechanisms for generating action potentials and trains of action potentials in real excitable cells can be obtained from the analysis of synthetic excitable cells that express a controlled repertoire of ion channels.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Hsu H,Huang E,Yang XC,Karschin A,Labarca C,Figl A,Ho B,Davidson N,Lester HAdoi
10.1016/S0006-3495(93)81153-6subject
Has Abstractpub_date
1993-09-01 00:00:00pages
1196-206issue
3eissn
0006-3495issn
1542-0086pii
S0006-3495(93)81153-6journal_volume
65pub_type
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