Show simple item record

dc.contributor.authorRigby, J. R.en_US
dc.contributor.authorPoelzing, S.en_US
dc.coverage.spatialUnited Statesen_US
dc.date.accessioned2017-02-03T15:13:21Z
dc.date.available2017-02-03T15:13:21Z
dc.date.issued2011-02-08en_US
dc.identifier.urihttp://hdl.handle.net/10919/74921
dc.description.abstractINTRODUCTION: Presently, there are no established methods to measure multiple ion channel types simultaneously and decompose the measured current into portions attributable to each channel type. This study demonstrates how impedance spectroscopy may be used to identify specific frequencies that highly correlate with the steady state current amplitude measured during voltage clamp experiments. The method involves inserting a noise function containing specific frequencies into the voltage step protocol. In the work presented, a model cell is used to demonstrate that no high correlations are introduced by the voltage clamp circuitry, and also that the noise function itself does not introduce any high correlations when no ion channels are present. This validation is necessary before the technique can be applied to preparations containing ion channels. The purpose of the protocol presented is to demonstrate how to characterize the frequency response of a single ion channel type to a noise function. Once specific frequencies have been identified in an individual channel type, they can be used to reproduce the steady state current voltage (IV) curve. Frequencies that highly correlate with one channel type and minimally correlate with other channel types may then be used to estimate the current contribution of multiple channel types measured simultaneously. METHODS: Voltage clamp measurements were performed on a model cell using a standard voltage step protocol (-150 to +50 mV, 5mV steps). Noise functions containing equal magnitudes of 1-15 kHz frequencies (zero to peak amplitudes: 50 or 100mV) were inserted into each voltage step. The real component of the Fast Fourier transform (FFT) of the output signal was calculated with and without noise for each step potential. The magnitude of each frequency as a function of voltage step was correlated with the current amplitude at the corresponding voltages. RESULTS AND CONCLUSIONS: In the absence of noise (control), magnitudes of all frequencies except the DC component correlated poorly (|R|<0.5) with the IV curve, whereas the DC component had a correlation coefficient greater than 0.999 in all measurements. The quality of correlation between individual frequencies and the IV curve did not change when a noise function was added to the voltage step protocol. Likewise, increasing the amplitude of the noise function also did not increase the correlation. Control measurements demonstrate that the voltage clamp circuitry by itself does not cause any frequencies above 0 Hz to highly correlate with the steady-state IV curve. Likewise, measurements in the presence of the noise function demonstrate that the noise function does not cause any frequencies above 0 Hz to correlate with the steady-state IV curve when no ion channels are present. Based on this verification, the method can now be applied to preparations containing a single ion channel type with the intent of identifying frequencies whose amplitudes correlate specifically with that channel type.en_US
dc.languageengen_US
dc.relation.urihttp://www.ncbi.nlm.nih.gov/pubmed/21339724en_US
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectElectric Impedanceen_US
dc.subjectIon Channelsen_US
dc.subjectPatch-Clamp Techniquesen_US
dc.subjectSignal Processing, Computer-Assisteden_US
dc.subjectSpectrum Analysisen_US
dc.titleRecapitulation of an ion channel IV curve using frequency components.en_US
dc.typeArticle - Refereed
dc.description.versionPublished online (Publication status)en_US
dc.contributor.departmentBiomedical Engineering and Mechanicsen_US
dc.contributor.departmentFralin Biomedical Research Institute at VTCen_US
dc.title.serialJ Vis Expen_US
dc.identifier.doihttps://doi.org/10.3791/2361
dc.type.otherResearch Support, N.I.H., Extramuralen_US
dc.type.otherVideo-Audio Mediaen_US
dc.identifier.issue48en_US
dc.identifier.eissn1940-087Xen_US
pubs.organisational-group/Virginia Tech
pubs.organisational-group/Virginia Tech/All T&R Faculty
pubs.organisational-group/Virginia Tech/Faculty of Health Sciences
pubs.organisational-group/Virginia Tech/University Research Institutes
pubs.organisational-group/Virginia Tech/University Research Institutes/Virginia Tech Carilion Research Institute


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record