Ion trapping with fast-response ion-selective microelectrodes enhances detection of extracellular ion channel gradients
Messerli, Mark A.
Collis, Leon P.
Smith, Peter J. S.
MetadataShow full item record
Previously, functional mapping of channels has been achieved by measuring the passage of net charge and of specific ions with electrophysiological and intracellular fluorescence imaging techniques. However, functional mapping of ion channels using extracellular ion-selective microelectrodes has distinct advantages over the former methods. We have developed this method through measurement of extracellular K+ gradients caused by efflux through Ca2+-activated K+ channels expressed in Chinese hamster ovary cells. We report that electrodes constructed with short columns of a mechanically stable K+-selective liquid membrane respond quickly and measure changes in local [K+] consistent with a diffusion model. When used in close proximity to the plasma membrane (<4 μm), the ISMs pose a barrier to simple diffusion, creating an ion trap. The ion trap amplifies the local change in [K+] without dramatically changing the rise or fall time of the [K+] profile. Measurement of extracellular K+ gradients from activated rSlo channels shows that rapid events, 10–55 ms, can be characterized. This method provides a noninvasive means for functional mapping of channel location and density as well as for characterizing the properties of ion channels in the plasma membrane.
Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Biophysical Journal 96 (2009): 1597-1605, doi:10.1016/j.bpj.2008.11.025.
Showing items related by title, author, creator and subject.
CTD observations in the Great South Channel during the South Channel Ocean Productivity Experiment, SCOPEX, May-June 1989 Limeburner, Richard; Beardsley, Robert C. (Woods Hole Oceanographic Institution, 1989-11)CTD and acoustic Doppler current profiler (ADCP) observations were made in the Great South Channel (GSC) off the New England coast during R/V Endeavor cruise EN196 May 18 to June 12, 1989 as part of the South Channel ...
Hulburt, Edward M. (2007-06-11)The use of logical validity and empirical data will show that natural selection occurs at the micro-evolutionary level but does not occur at the macro-evolutionary level.
New criteria for selecting the origin of DNA replication in Wolbachia and closely related bacteria Ioannidis, Panagiotis; Dunning Hotopp, Julie C.; Sapountzis, Panagiotis; Siozios, Stefanos; Tsiamis, Georgios; Bordenstein, Seth R.; Baldo, Laura; Werren, John H.; Bourtzis, Kostas (BioMed Central, 2007-06-20)Background: The annotated genomes of two closely related strains of the intracellular bacterium Wolbachia pipientis have been reported without the identifications of the putative origin of replication (ori). Identifying ...