AJP - Renal Physiology, Vol 259, Issue 6 895-F901, Copyright © 1990 by American Physiological Society
Postnatal development of oxidative enzymes in various rat nephron segments: effect of weaning on different diets
J. Bastin, F. Djouadi, J. P. Geloso and C. Merlet-Benichou
Laboratoire de Differenciation Fonctionnelle, Institut National de la Sante et de la Recherche Medicale Unite 319, Universite Paris 7, France.
Activities of fumarase and 3-hydroxyacylCoA dehydrogenase (3-OHDH) were
determined in homogenates of rat kidneys between day 21 of gestation and
postnatal day 10 and in single isolated nephron segments at postnatal days
16, 21, and 30, and in adult segments. For 3-OHDH activity, main
developmental changes were found in proximal convoluted (PCT) and straight
tubules (PST) and were characterized by an overshoot of adult level from
postnatal days 21 to 30 (59.7 +/- 3.0 and 37.5 +/- 3.4 at day 21 vs. adult
values 27.1 +/- 1.5 and 22.7 +/- 1.5 mol.kg dry wt-1.h-1). When rats were
precociously weaned on day 16 and fed a diet containing lipid to equal 13%
of total caloric intake, a significant decrease in 3-OHDH activity was
observed in some parts of the nephron. These changes could be prevented by
maintaining early weaned animals on high-fat diet providing 70% of total
calories as lipid. Results suggest that changes in fat content of diet
during kidney maturation can in part regulate 3-OHDH activity in some
nephron segments. Fumarase activity increased 2.6-fold in the medullary
thick ascending limb between days 16 and 30; pattern of development was
similar to the one reported for Na(+)-K(+)-ATPase activity in this segment.
High levels of both enzymes were reached noticeably earlier during
development in PCT and PST than in medullary thick ascending limb, which
emphasizes metabolic heterogeneity of developing rat kidney nephron.
