AJP - Renal Physiology, Vol 250, Issue 3 525-F531, Copyright © 1986 by American Physiological Society
Prostaglandins may mediate chloride concentration gradient across domes formed by MDCK1 cells
M. D. Lifschitz
The MDCK1 and LLC-PK1 cell lines have been used to characterize
transepithelial transport in isolated culture. Both can be maintained in
continuous culture and form domes that represent fluid actively transported
from luminal to contraluminal surface. Fluid in domes from LLC-PK1 cells
was isotonic with the culture medium and no Cl gradient between domes and
medium was present. Fluid from domes formed by MDCK1 cells was also
isotonic with respect to Na and K but there was a persistent Cl
concentration gradient. To evaluate prostaglandin (PG) production by these
cell lines, the culture medium was analyzed for PGE. LLC-PK1 cells released
no measurable PGE; MDCK1 cells regularly released PGE both during basal
conditions and after augmentation of PG synthesis by a high Ca
concentration in the medium. Qualitatively similar results had previously
been found with these cell lines when PG synthesis was augmented with
addition of arachidonic acid or Ca ionophore A23187, and PGE or
6-keto-prostaglandin F1 alpha was measured in the medium. To evaluate
whether PGs might be responsible for the Cl gradient across MDCK1 cells,
indomethacin or meclofenamate was added. There was a marked decrease in the
Cl gradient with either agent at 5 h. To evaluate the possibility that PGE2
or PGI2 plays a role in maintaining this Cl gradient, further studies were
done in which indomethacin was added to the culture medium to block
endogenous PG synthesis, and exogenous PGE2 or PGI2 was added. Although
addition of PGE2 was without effect, addition of PGI2 to
indomethacin-treated cells maintained the Cl gradient for at least 5
h.(ABSTRACT TRUNCATED AT 250 WORDS)
