AJP - Renal Physiology, Vol 248, Issue 6 762-F766, Copyright © 1985 by American Physiological Society
Transmembrane potential of renal papillary epithelial cells: effect of urea and DDAVP
J. M. Sands, E. J. Ivy and R. Beeuwkes 3rd
To define how renal papillary epithelial cells respond to wide changes in
the ionic and osmotic composition of their environment, measurements were
made of the transmembrane potential differences (PD) of rat renal papillary
epithelial cells in vitro in media containing 100 mM NaCl, 100 mM KCl, 1.5
mM CaCl2, and 1 mM MgSO4 plus varying amounts of urea and/or sucrose up to
1,400 mM. Glass microelectrodes (resistance 25-75 M Omega) were used. With
added sucrose, no change in PD from the initial value of -9.3 +/- 1.3 (SD)
mV (n = 29) (cell interior negative) was found. With added urea, alone or
while osmolality was maintained nearly constant with sucrose, the PD
changed in a triphasic manner, depolarizing to -5.3 mV at 50 mM urea,
hyperpolarizing to -20.0 mV at 150 mM urea, and then depolarizing again to
-5.5 mV at 1,400 mM urea. When bath potassium was decreased to 10 meQ/liter
(choline replacement) the PD hyperpolarized to -46.9 +/- 5.0 (SD) mV (n =
32). DDAVP, a nonpressor vasopressin analogue, and 8-bromo-cAMP depolarized
the membrane to -5 mV in the presence of urea but did not change PD when
urea was absent. These observations suggest an interaction between urea and
ionic movement or conductance in rat renal papillary epithelial cells.
