Isolated epithelial cells from amphibian urinary bladder express
functional gap-junctional hemichannels.
Vanoye, Carlos G., Leoncio Vergara, and Luis Reuss.
Department of Physiology and Biophysics, University of Texas
Medical Branch, Galveston, TX 77555-0641
APStracts 5:0271C, 1998.
Exposure of the urinary bladder epithelium of Necturus maculosus (NUB)
to protease and collagenase yields ca. 50% isolated polarized cells.
These cells express a membrane current slowly activated with
depolarization or by removal of external divalent cations. The
biophysical and pharmacological properties of the current are largely
consistent with those of gap-junctional hemichannels. After removal
of divalent cations, the cells can also be loaded with 5(6)
-carboxyfluorescein, a hydrophylic fluorescent anionic dye, and
exposure to dye reduces the current in a way dependent on membrane
voltage and side of application. In contrast, Necturus gallbladder
(NGB) cells exhibit no membrane conductance attributable to gap
-junctional hemichannels, although previous studies reveal the
persistence of gap-junction plaques on the plasma membrane. We
conclude that functional gap-junctional hemichannels can be expressed
on the surface of certain isolated epithelial cells and that this is
not a necessary consequence of the isolation procedure. These
structures may contribute to cell damage under pathological
conditions involving cell detachment.
Received 3 September 1998; accepted in final form 1 October 1998.
APS Manuscript Number C421-8.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 20 October 1998