AJP - Renal Physiology, Vol 259, Issue 6 872-F881, Copyright © 1990 by American Physiological Society
Oxytocin receptors in rat kidney during development
A. Schmidt, S. Jard, J. J. Dreifuss and E. Tribollet
Centre National de la Recherche Scientifique, Institut National de la Sante et de la Recherche Medicale, Montpellier, France.
The development and characteristics of oxytocin (OT) receptors in the rat
kidney were studied by light-microscopic autoradiography and on membrane
preparations using the iodinated OT antagonist
125I-d(CH2)5[Tyr(Me)2,Thr4,Orn8,Tyr(NH2)9]OT. Specific binding was first
detected by autoradiography at embryonic day 17 (E17) in both the cortex
and the medulla. Cortical labeling was found thereafter at all ages
examined including in the adult (postnatal day 90, PN90). It was localized
on the distal tubule at the level of the juxtaglomerular apparatus.
Medullary binding was detected only transiently during two stages of
development, first, before PN6, and second, at the approximate time of
weaning (PN20-PN30). Binding studies on crude membranes prepared from whole
kidneys of animals aged between PN1 and PN15 showed a single class of
high-affinity binding sites, with a dissociation constant of 0.13 +/- 0.08
nM. Thus transient OT binding sites expressed in the medulla do not differ
from cortical OT binding sites; moreover, the ligand selectivity of kidney
OT receptors regardless of location and age appears similar to that of
previously characterized OT receptors. Our results suggest that OT may play
a role in both renal development and renal function.
