AJP - Cell Physiology, Vol 263, Issue 3 C563-C572, Copyright © 1992 by American Physiological Society
Regulation by calcitonin of Na(+)-K(+)-Cl- cotransport in a rabbit thick ascending limb cell line
T. Vuillemin, J. Teulon, M. Geniteau-Legendre, B. Baudouin, S. Estrade, R. Cassingena, P. Ronco and A. Vandewalle
Institut National de la Sante et de la Recherche Medicale (INSERM) U. 64, Hopital Tenon, Paris, France.
The hormonal regulation of a Na(+)-K(+)-Cl- cotransport was investigated in
a renal tubule cell line (RC.SV2 cells) transformed by the simian virus 40.
This cell line has the main characteristics of cells from the thick
ascending limb of Henle, including the presence of Tamm-Horsfall protein
and stimulation of adenosine 3',5'-cyclic monophosphate (cAMP) production
by calcitonin (CT). Kinetic studies with 22Na+, 36Cl-, and 86Rb+ indicated
the existence of a Na(+)-K(+)-Cl- cotransport with a stoichiometry of
1Na+:1K+: 2Cl-. All compounds stimulating cAMP production enhanced the
ouabain-resistant bumetanide-sensitive (Or-Bs) Rb+ influx mediated by
Na(+)-K(+)-Cl- cotransport. CT (100 ng/ml) increased the Or-Bs influx
twofold by enhancing maximum velocity without changing the apparent
Michaelis constant. The K(+)-channel blocker barium blunted the
CT-stimulated Or-Bs influx by 64-74%, whereas the Cl(-)-channel blocker
5-nitro-2-(3-phenylpropylamino)benzoate reduced the CT-stimulated influx by
28-40%. These results suggest that CT stimulates the Na(+)-K(+)-Cl-
cotransport by a cAMP-dependent mechanism and that K+ recycling through K+
membrane channels is an important modulator of cotransporter-mediated ion
fluxes.
