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Prenatal programming of rat cortical collecting tubule sodium transport.

Abstract

Prenatal insults have been shown to lead to elevated blood pressure in offspring when they are studied as adults. Prenatal administration of dexamethasone and dietary protein deprivation have demonstrated that there is an increase in transporter abundance for a number of nephron segments but not the subunits of the epithelial sodium channel (ENaC) in the cortical collecting duct. Recent studies have shown that aldosterone is elevated in offspring of protein-deprived mothers when studied as adults, but the physiological importance of the increase in serum aldosterone is unknown. As an indirect measure of ENaC activity, we compared the natriuretic response to benzamil in offspring of mothers who ate a low-protein diet (6%) with those who ate a normal diet (20%) for the last half of pregnancy. The natriuretic response to benzamil was greater in the 6% group (821.1 ± 161.0 μmol/24 h) compared with the 20% group (279.1 ± 137.0 μmol/24 h), consistent with greater ENaC activity in vivo (P < 0.05). In this study, we also directly studied cortical collecting tubule function from adult rats using in vitro microperfusion. There was no difference in basal or vasopressin-stimulated osmotic water permeability. However, while cortical collecting ducts of adult offspring whose mothers ate a 20% protein diet had no sodium transport (-1.9 ± 3.1 pmol·mm(-1)·min(-1)), the offspring of rats that ate a 6% protein diet during the last half of pregnancy had a net sodium flux of 10.7 ± 2.6 pmol·mm(-1)·min(-1) (P = 0.01) in tubules perfused in vitro. Sodium transport was measured using ion-selective electrodes, a novel technique allowing measurement of sodium in nanoliter quantities of fluid. Thus we directly demonstrate that there is prenatal programming of cortical collecting duct sodium transport.

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  • Authors

    Cheng CJ, Lozano G, Baum M

    Institution

    Dept. of Pediatrics, U.T. Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9063, USA.

    Source

    American journal of physiology. Renal physiology 302:6 2012 Mar pg F674-8

    MeSH

    Aldosterone
    Amiloride
    Animals
    Biological Transport
    Diet, Protein-Restricted
    Dietary Proteins
    Diuretics
    Epithelial Sodium Channel
    Female
    Fetal Development
    Kidney Cortex
    Kidney Tubules, Collecting
    Maternal Nutritional Physiological Phenomena
    Pregnancy
    Prenatal Exposure Delayed Effects
    Rats
    Rats, Sprague-Dawley
    Sodium

    Pub Type(s)

    Journal Article
    Research Support, N.I.H., Extramural
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    22189946