Membrane-pipette interactions underlie delayed voltage activation of mechanosensitive channels in Xenopus oocytes

Ziv Gil, Karl L. Magleby, Shai D. Silberberg

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

To investigate the mechanism for the delayed activation by voltage of the predominant mechanosensitive (MS) channel in Xenopus oocytes, currents were recorded from on-cell and excised patches of membrane with the patch clamp technique and from intact oocytes with the two-electrode voltage clamp technique. MS channels could be activated by stretch in inside-out, on-cell, and outside-out patch configurations, using pipettes formed of either borosilicate or soft glass. In inside-out patches formed with borosilicate glass pipettes, depolarizing voltage steps activated MS channels in a cooperative manner after delays of seconds. This voltage-dependent activation was not observed for outside-out patches. Voltage-dependent activation was also not observed when the borosilicate pipettes were either replaced with soft glass pipettes or coated with soft glass. When depolarizing voltage steps were applied to the whole oocyte with a two-electrode voltage clamp, currents that could be attributed to MS channels were not observed. Yet the same depolarizing steps activated MS channels in on-cell patches formed with borosilicate pipettes on the same oocyte. These observations suggest that the delayed cooperative activation of MS channels by depolarization is not an intrinsic property of the channels, but requires interaction between the membrane and patch pipette.

Original languageEnglish (US)
Pages (from-to)3118-3127
Number of pages10
JournalBiophysical journal
Volume76
Issue number6
DOIs
StatePublished - Jun 1999

ASJC Scopus subject areas

  • Biophysics

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