Angiotensin II and the maturation of renal cortical Na+/H+ exchanger activity during fetal life in sheep

Edward N Guillery; Michael S Mathews; John Orlowski; Jean E Robillard

doi:10.1152/ajpregu.1996.271.6.R1507

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Angiotensin II and the maturation of renal cortical Na+/H+ exchanger activity during fetal life in sheep

Journal article

Peer reviewed

Angiotensin II and the maturation of renal cortical Na+/H+ exchanger activity during fetal life in sheep

Edward N Guillery, Michael S Mathews, John Orlowski and Jean E Robillard

The American journal of physiology, Vol.271(6 Pt 2), pp.R1507-R1513

12/01/1996

DOI: 10.1152/ajpregu.1996.271.6.R1507

PMID: 8997346

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Abstract

The postnatal rise in renal Na+ reabsorption is associated with an increase in proximal tubule apical membrane Na+/H+ exchanger (NHE) activity in sheep. Inasmuch as circulating angiotensin II (ANG II) levels increase immediately after birth and ANG II is known to upregulate NHE activity in the adult proximal tubule, we postulated that ANG II plays a role in mediating maturational changes in NHE activity. We therefore studied the effects of ANG II infusion (10 micrograms/h) for 24 h on renal cortical NHE activity in chronically instrumented, twin ovine fetuses (129 +/- 2 days gestation, term is 145 days, n = 10 pairs); one twin of each pair served as a control. After 24 h, the fetuses were killed and brush-border membrane vesicles (BBMV) were prepared from the renal cortices. Postinfusion plasma ANG II levels were significantly higher and plasma renin activities were significantly lower in treated fetuses compared with controls. Kinetic analysis revealed an increase in NHE activity after ANG II treatment; however, the difference was not statistically significant: maximal velocity (in nmol.s-1.mg protein-1) control 1.65 +/- 0.50, treated 2.31 +/- 0.66 (P = 0.11, n = 9 pairs); Michaelis constant control 8.29 +/- 1.17 mM, treated 9.84 +/- 1.26 mM (P = 0.11). Northern blots of total RNA from the cortices of these animals were hybridized to a D-[32P]UTP-labeled antisense RNA probe prepared from a 1.3-kb rat NHE3 cDNA fragment. There were no differences between the groups in NHE3 mRNA levels (32P counts were control 413 +/- 54, treated 340 +/- 46). ANG II does not appear to play an important role in the regulation of NHE activity in the proximal tubule of the near-term sheep fetus.

Pregnancy

Angiotensin II - pharmacology

Animals

Arteries

Blood Pressure - drug effects

Embryonic and Fetal Development

Female

Fetal Blood - drug effects

Fetus - drug effects

Fetus - metabolism

Fetus - physiology

Gene Expression - drug effects

Heart Rate, Fetal - drug effects

Kidney - embryology

Kidney Cortex - drug effects

Kidney Cortex - embryology

Kidney Cortex - metabolism

Kidney Tubules, Proximal - drug effects

Kidney Tubules, Proximal - embryology

Kidney Tubules, Proximal - metabolism

Rats

Sheep - embryology

Sodium-Hydrogen Exchangers - genetics

Sodium-Hydrogen Exchangers - metabolism

Details

Title: Subtitle: Angiotensin II and the maturation of renal cortical Na+/H+ exchanger activity during fetal life in sheep
Creators: Edward N Guillery - University of Iowa
Michael S Mathews - University of Iowa
John Orlowski - University of Iowa
Jean E Robillard - University of Iowa
Resource Type: Journal article
Publication Details: The American journal of physiology, Vol.271(6 Pt 2), pp.R1507-R1513
DOI: 10.1152/ajpregu.1996.271.6.R1507
PMID: 8997346
ISSN: 0002-9513
eISSN: 1522-1490
Grant note: DK-43961 / NIDDK NIH HHS HL-14388 / NHLBI NIH HHS DK-38302 / NIDDK NIH HHS
Language: English
Date published: 12/01/1996
Academic Unit: Molecular Physiology and Biophysics; Nephrology, Dialysis and Transplantation; Stead Family Department of Pediatrics; Medicine Administration
Record Identifier: 9984774212202771

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