AJP - Cell Physiology, Vol 257, Issue 6 C1108-C1112, Copyright © 1989 by American Physiological Society
p-aminohippurate transport in the airways: role of Na+ and HCO3-
M. M. Cloutier
Department of Pediatrics, University of Connecticut Health Center, Farmington 06032.
The role of Na+ and HCO3- in the transport of p-aminohippurate (PAH) across
the canine tracheal epithelium was investigated using Ussing chamber
techniques and radiolabeled PAH. Under control conditions, net PAH
absorption or a tendency toward net PAH absorption was observed. Neither
amiloride (10(-4) M), furosemide (10(-3) M), ouabain (2 x 10(-4) M), nor
Na+ substitution of the Ringer solution with choline had any effect on
unidirectional PAH fluxes. When the Ringer solution was replaced with a
HCO3(-)-free solution, net PAH absorption was consistently observed. In
HCO3(-)-free experiments, unidirectional PAH absorptive fluxes were
inhibited by mucosal addition of either of the stilbene derivatives,
4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS, 10(-4) M) or
4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS, 10(-4) M).
DIDS was more effective than SITS and was also effective in inhibiting PAH
absorption in tissues bathed in Ringer solution. Submucosal DIDS or SITS
had no effect on PAH fluxes either in HCO3(-)-free or Ringer experiments.
We conclude that PAH transport in canine tracheal epithelium occurs by a
HCO3(-)-PAH exchange process located on the luminal membrane. PAH transport
is not Na+ dependent but is inhibited by both DIDS and SITS.
