AJP - Renal Physiology, Vol 248, Issue 4 552-F564, Copyright © 1985 by American Physiological Society
Cellular heterogeneity of uridine incorporation in collecting tubules: effect of DOCA
A. Vandewalle, F. Cluzeaud, M. Chavance and J. P. Bonvalet
In previous studies we showed that in vitro uridine incorporation along the
renal tubule is heterogeneous and that DOCA induces a stimulation of RNA
synthesis in distal cortical and medullary structures. The present work
examines by autoradiography of isolated tubules and renal tissue sections
the cellular heterogeneity of the connecting (CNT) and cortical collecting
(CCT) tubules after in vivo injection of [3H]uridine in normal and
DOCA-treated rabbits. Data confirmed the profile of uridine incorporation
along the tubule, which was found in in vitro experiments, and the
DOCA-induced stimulation of RNA synthesis. In microdissected CNT and CCT of
control kidneys, statistical analysis of the distribution of labeling
revealed the presence of two distinct cell populations: one with low
labeling (2-3 silver grains per nucleus) and one with high labeling
(10-13), which represent 64 and 36%, respectively (CNT), and 74 and 26%,
respectively (CCT), of the whole population. Histological data showed that
the respective proportions of intercalated cells (29% in CNT; 21% in CCT)
and connecting tubule cells (65%) or principal cells (79%) are close to
those of the populations with high or low labeling. In addition,
autoradiographs on renal sections directly demonstrated that the labeling
of intercalated cells (19.3 silver grains/100 micron2 nuclear surface in
CNT; 14.7 in CCT) was three times higher than that of connecting (6.6) or
principal (5.8) cells. In isolated CNT and CCT, DOCA induced similar
absolute increases in the labeling of the two populations. However, the
relative increase was more than two times higher in the population with low
labeling (+131% in CNT, +210% in CCT) than in the one with high labeling
(+71% and +98%). We conclude that cell population of the collecting
cortical tubule (CNT and CCT) is heterogeneous with regard to uridine
incorporation, reflecting RNA synthesis.
