Correlation of open cell-attached and excised patch clamp techniques.
The excised patch clamp configuration provides a unique technique for some types of single channel analyses, but maintenance of stable, long-lasting preparations may be confounded by rundown and/or rapid loss of seal. Studies were performed on the amiloride-sensitive Na+ channel, located on the apical surface of A6 cells, to determine whether the nystatin-induced open cell-attached patch could serve as an alternative configuration. Compared to excised inside-out patches, stable preparations were achieved more readily with the open cell-attached patch (9% vs. 56% of attempts). In both preparations, the current voltage (I-V) relation was linear, current amplitudes were equal at opposite equivalent clamped voltages, and Erev was zero in symmetrical Na+ solutions, indicating similar Na+ activities on the cytosolic and external surfaces of the patch. Moreover, there was no evidence that nystatin altered channel activity in the patch because slope conductance (3-4pS) and Erev (75 mV), when the bath was perfused with a high K:low Na solution (ENa = 80 mV), were nearly equal in both patch configurations. Our results therefore indicate that the nystatin-induced open cell-attached patch can serve as an alternative approach to the excised inside-out patch when experiments require modulation of univalent ions in the cytosol.
Filipovic
D
D
Department of Internal Medicine, Yale School of Medicine, New Haven, CT, USA.
Hayslett
J P
JP
D000818:Animals; D002460:Cell Line; D004553:Electric Conductivity; D007473:Ion Channels / Q000032:analysis; D007668:Kidney / Q000166:cytology; D008564:Membrane Potentials; D018408:Patch-Clamp Techniques / Q000379:methods*; D015222:Sodium Channels / Q000502:physiology; D014982:Xenopus laevis
D007473:Ion Channels; D015222:Sodium Channels