A delayed rectifier potassium current in Xenopus oocytes

L. Lu, C. Montrose-Rafizadeh, T. C. Hwang, William B Guggino

Research output: Contribution to journalArticle

Abstract

A delayed voltage-dependent K+ current endogenous to Xenopus oocytes has been investigated by the voltage-clamp technique. Both activation and inactivation of the K+ current are voltage-dependent processes. The K+ currents were activated when membrane potential was depolarized from a holding potential of -90 to -50mV. The peak current was reached within 150 ms at membrane potential of +30mV. Voltage-dependent inactivation of the current was observed by depolarizing the membrane potential from -50 to 0 mV at 10-mV increments. Voltage-dependent inactivation was a show process with a time constant of 16.5 s at -10 mV. Removal of Ca2+ from the bath has no effect on current amplitudes, which indicates that the current is Ca2+ -insensitive. Tail current analysis showed that reversal potentials were shifted by changing external K+ concentration, as would be expected for a K+-selective channel. The current was sensitive to quinine, K+ channel blocker, with a K(i) of 35 μM. The blockade of quinine is voltage-independent in the range of -20 to +66mV. Whereas oocytes from the same animal have a relatively homogeneous current distribution, average amplitude of the K+ current varied among oocytes from different animals from 30 to 400 nA at membrane potential of +30 mV. Our results indicate the presence of the endogenous K+ current in Xenopus oocytes with characteristics of the delayed rectifier found in some nerve and muscle cells.

Original languageEnglish (US)
Pages (from-to)1117-1123
Number of pages7
JournalBiophysical Journal
Volume57
Issue number6
StatePublished - 1990

Fingerprint

Xenopus
Membrane Potentials
Oocytes
Potassium
Quinine
Patch-Clamp Techniques
Baths
Muscle Cells
Tail
Neurons

ASJC Scopus subject areas

  • Biophysics

Cite this

Lu, L., Montrose-Rafizadeh, C., Hwang, T. C., & Guggino, W. B. (1990). A delayed rectifier potassium current in Xenopus oocytes. Biophysical Journal, 57(6), 1117-1123.

A delayed rectifier potassium current in Xenopus oocytes. / Lu, L.; Montrose-Rafizadeh, C.; Hwang, T. C.; Guggino, William B.

In: Biophysical Journal, Vol. 57, No. 6, 1990, p. 1117-1123.

Research output: Contribution to journalArticle

Lu, L, Montrose-Rafizadeh, C, Hwang, TC & Guggino, WB 1990, 'A delayed rectifier potassium current in Xenopus oocytes', Biophysical Journal, vol. 57, no. 6, pp. 1117-1123.
Lu L, Montrose-Rafizadeh C, Hwang TC, Guggino WB. A delayed rectifier potassium current in Xenopus oocytes. Biophysical Journal. 1990;57(6):1117-1123.
Lu, L. ; Montrose-Rafizadeh, C. ; Hwang, T. C. ; Guggino, William B. / A delayed rectifier potassium current in Xenopus oocytes. In: Biophysical Journal. 1990 ; Vol. 57, No. 6. pp. 1117-1123.
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