Expression of the thiazide-sensitive na-cl cotransporter in rat and
human kidney.
Obermiller, Nicholas, Paul Bernstein, Heino Velazquez, Robert Reilly,
Doris Moser, David H. Ellison, Sebastian Bachmann.
Section of Nephrology, Yale University School of Medicine, & VA
Medical Center, West Haven, CT USA 06520-8029 & Department of
Anatomy, Ruprecht-Karls-Universit[grave]et, Heidelberg, Germany
APStracts 2:0161F, 1995.
An electroneutral thiazide-sensitive Na-Cl cotransport pathway (TSC)
has been localized functionally to the distal convoluted tubule
(DCT), although the TSC has also been detected in the connecting
tubule (CNT), the cortical collecting duct, and the medullary
collecting tubule as well. The present experiments were designed to
localize expression of message for the TSC in rat and human kidney. A
riboprobe, generated from the mouse TSC, was used for in situ
hybridization. Simultaneous immunocytochemistry, using antibodies to
Tamm Horsfall protein, band 3, and the Na+/Ca2+ exchanger, permitted
delineation of specific nephron segments. In rat, message for the TSC
was highly expressed in distal convoluted tubule (DCT) cells, but not
elsewhere. The transition from thick ascending limb to DCT was
abrupt, whereas the transition to CNT was gradual. In the more distal
region of rat DCT (DCT-2), which contained few intercalated cells,
both TSC message and Na+/Ca2+ exchanger immunoreactivity were
present. Treatment of rats with furosemide for 5 days increased
expression of TSC message within the DCT, but did not induce its
expression elsewhere. In human, expression of TSC message was also
highest in cells of the DCT. In this species, however, expression
extended well into the CNT. These experiments indicate that the TSC
is expressed predominantly by DCT cells in both rat and human,
although expression extends into the CNT cells in humans. They also
show that the TSC and Na+/Ca2+ exchanger are co-expressed by a
subpopulation of DCT cells near the junction with the CNT .
Received 25 April 1995; accepted in final form 10 July 1995.
APS Manuscript Number F134-5.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 September 1995.