Xenopus laevis oocytes contain endogenous large conductance Ca2(+)-activated K+ channels.

Published

Journal Article

Xenopus laevis oocytes have become a pre-eminent tool for studying cloned ion channels, primarily because they intrinsically express low levels of most types of ion channels. However, when these cells are used for single channel studies, it is essential to determine whether or not oocytes contain even low levels of endogenous ion channels with properties similar to the channel being investigated. We show here that X. laevis oocytes express endogenous large-conductance Ca2(+)-activated K+ channels with properties similar to mammalian isoforms of this channel. The endogenous channels exhibit a voltage-dependence of 12-14 mV per e-fold change in open probability (po), can be activated by micromolar Ca2+ concentrations, and have a single channel conductance of approximately 200 pS in symmetrical 110 mM K+ solutions. Patch clamp experiments indicate that this endogenous channel is present at low densities (approximately 1 channel/3000 microns2). If endogenous channel subunits can form functional tetramers with other exogenous potassium channel subunits, then they will give rise to the expression of a heterogeneous channel population. Therefore, studies involving the heterologous expression of large-conductance Ca2(+)-activated K+ channels in Xenopus laevis oocytes require careful analysis and interpretation.

Full Text

Cited Authors

  • Krause, JD; Foster, CD; Reinhart, PH

Published Date

  • January 1, 1996

Published In

Volume / Issue

  • 35 / 7

Start / End Page

  • 1017 - 1022

PubMed ID

  • 8938732

Pubmed Central ID

  • 8938732

Electronic International Standard Serial Number (EISSN)

  • 1873-7064

International Standard Serial Number (ISSN)

  • 0028-3908

Digital Object Identifier (DOI)

  • 10.1016/0028-3908(96)00134-7

Language

  • eng