AJP - Cell Physiology, Vol 263, Issue 3 C573-C583, Copyright © 1992 by American Physiological Society
Comparison of apical and basal surfaces of confluent endothelial cells: patch-clamp and viral studies
M. Colden-Stanfield, E. B. Cramer and E. K. Gallin
Department of Physiology, Armed Forces Radiobiology Research Institute, Bethesda, Maryland 20889-5145.
The distribution of inwardly rectifying (Ki) and calcium-activated (KCa)
potassium channels on the apical and basal surfaces of bovine aortic
endothelial cells (BAECs) was examined by inverting BAEC monolayers onto
polylysine-coated cover slips. To monitor cellular polarity, we examined
human red blood cell adherence (hemadsorption) to the influenza virus
protein, hemagglutinin (HA), and virus budding on the surface of infected
BAECs. Hemadsorption and virus budding occurred on the apical surface but
were not apparent on the basal surface of monolayers 1 and 5 h after
inversion, although cellular HA antigen localization confirmed that all
monolayers were infected. In contrast, by 9.5 and 24 h after inversion,
hemadsorption was evident on the "new" apical surface. Single-channel
patch-clamp analysis revealed the presence of both Ki and KCa channels on
the apical surface and basal surface of BAEC monolayers 2-5 h after
inversion. K channel conductance and kinetics were similar regardless of
the surface monitored. This nonenzymatic mechanical technique of exposing
the basal surface of endothelium provides a useful tool to study the
distribution of ion channels in endothelium and in other polarized cell
types grown in tissue culture.
