Localization of the extracellular ca2+-sensing receptor and
parathyroid hormone/parathyroid hormone-related protein receptor in
rat kidney.
Riccardi, Daniela, Wen-Sen Lee, Kaechoong Lee, Gino V. Segre, Edward
M. Brown, and Steven C. Hebert.
Laboratory of Molecular Physiology and Biophysics, Renal Division,
and Endocrine-Hypertension Unit, Department of Medicine, Brigham &
Women's Hospital, Endocrine Unit, Department of Medicine,
Massachusetts General Hospital, Harvard Medical School, Boston, MA,
02115
APStracts 3:0135F, 1996.
Using a strategy based on homology to the bovine parathyroid Ca2+
-sensing receptor previously identified by us (5), we have recently
isolated an extracellular, G protein-coupled Ca2+/polyvalent cation
-sensing receptor, RaKCaR (22) from rat kidney. The localization and
physiological role(s) of this receptor in the kidney are not well
understood. In the present study, we assessed the distribution of
mRNAs for RaKCaR and the parathyroid hormone/parathyroid hormone
-related protein (PTH/PTHrP) receptor along the rat nephron by in situ
hybridization and RT-PCR of microdissected nephron segments. Our
results show that transcripts for both receptors coexpress at
glomeruli, proximal convoluted tubule (PCT), proximal straight tubule
(PST), cortical thick ascending limb (CTAL), distal convoluted tubule
(DCT) and cortical collecting duct (CCD). In addition, RaKCaR (but
not PTH/PTHrP receptor) transcripts were found in the medullary thick
ascending limb (MTAL), outer medullary (OMCD) and inner (IMCD)
collecting ducts. These findings raise the possibility of roles for
RaKCaR not only in the regulation of divalent mineral reabsorption,
but also in water reabsorption and urinary concentration. Taken
together, our results provide new insights in understanding the
effects of hypercalcemia on hormone-stimulated salt and water
transport.
Received 5 February 1996; accepted in final form 16 July 1996.
APS Manuscript Number F37-6.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 4 August 1996