Sodium channels in membrane vesicles from cultured toad bladder cells

C. Asher, A. Moran, B. C. Rossier, H. Garty

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7 Scopus citations


Electrical potential-driven 22Na+ fluxes were measured in membrane vesicles prepared from TBM-18(cl23) cells (a clone of the established cell line TB-M). Fifty to seventy percent of the tracer uptake in vesicles derived from cells that were cultivated on a porous support were blocked by the diuretic amiloride. The amiloride inhibition constant was <0.1 μM, indicating that this flux is mediated by the apical Na+-specific channels. Vesicles prepared from cells that were not grown on a porous support exhibited much smaller amiloride-sensitive fluxes. Two Ca2+-dependent processes that down-regulate the channel conductance and were previously identified in native epithelia were found in the cultured cells as well. Vesicles isolated from cells that were preincubated with 5 x 10-7 M aldosterone for 16-20 h exhibited higher amiloride-sensitive conductance than vesicles derived from control, steroid-depleted cells. Thus membrane derived from TBM-18(cl23) cells can be used to characterize the epithelial Na+ channel and its hormonal regulation.

Original languageEnglish
Pages (from-to)23/4
JournalAmerican Journal of Physiology - Cell Physiology
Issue number4
StatePublished - 1 Jan 1988

ASJC Scopus subject areas

  • Physiology
  • Cell Biology


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