Abstract:
:The biophysical properties and cellular distribution of ion channels largely determine the input/output relationships of electrically excitable cells. A variety of patch pipette voltage clamp techniques are available to characterize ionic currents. However, when used by themselves, such techniques are not well suited to the task of mapping low-density channel distributions. We describe here a new voltage clamp method (the whole cell loose patch (WCLP) method) that combines whole-cell recording through a tight-seal pipette with focal extracellular stimulation through a loose-seal pipette. By moving the stimulation pipette across the cell surface and using a stationary whole-cell pipette to record the evoked patch currents, this method should be suitable for mapping channel distributions, even on large cells possessing low channel densities. When we applied this method to the study of currents in cultured chick myotubes, we found that the cell cable properties and the series resistance of the recording pipette caused significant filtering of the membrane currents, and that the filter characteristics depended in part upon the distance between the stimulating and recording pipettes. We describe here how we determined the filter impulse response for each loose-seal pipette placement and subsequently recovered accurate estimates of patch membrane current through deconvolution.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Anson BD,Roberts WMdoi
10.1016/S0006-3495(98)78003-8subject
Has Abstractpub_date
1998-06-01 00:00:00pages
2963-72issue
6eissn
0006-3495issn
1542-0086pii
S0006-3495(98)78003-8journal_volume
74pub_type
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