HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 289/4/R1099    most recent 00055.2005v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Boyce, A. C. Articles by Lumbers, E. R. Search for Related Content PubMed PubMed Citation Articles by Boyce, A. C. Articles by Lumbers, E. R.

DEVELOPMENTAL PHYSIOLOGY AND PREGNANCY

Effects of 7-day amino acid infusion on renal growth, function, and renin-angiotensin system in fetal sheep

¹Department of Physiology and Pharmacology, School of Medical Sciences, The University of New South Wales, Sydney; and ²Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Australia

Submitted 28 January 2005 ; accepted in final form 10 June 2005

These experiments examined whether renal growth and the fetal renin-angiotensin system could be stimulated by infusion of amino acids and whether chronic amino acid infusions restored glomerulotubular balance, which had been disrupted during 4-h infusions. Five fetal sheep aged 122 ± 1 days gestation received an infusion of alanine, glycine, proline and serine in 0.15 M saline at 0.22 mmol/min for 7 days. Six control fetuses were given saline at the same rate (5 ml/h). Kidney wet weights after amino acid infusion were 28% larger than control fetuses (P < 0.05), and renal angiotensinogen mRNA levels were 2.6-fold higher (P < 0.005). Circulating renin levels and renal renin mRNA levels were suppressed (P < 0.05), and renal renin protein levels tended to be lower. Arterial pressure was increased, and there was a marked, sustained natriuresis and diuresis. Glomerular filtration rate and filtered sodium were two-fold higher throughout infusion (P < 0.05). Fractional proximal sodium reabsorption, suppressed at 4 h (from 73.4 ± 6.5 to 53.7 ± 10.2%), did not return to control levels (36.1 ± 3.4% on day 7, P < 0.05). Distal sodium reabsorption was markedly increased (from 79 ± 25 to 261 ± 75 µmol/min by day 7, P < 0.005), but this was not sufficient to restore glomerulotubular balance. The resultant high rates of sodium excretion led to hyponatremia and polyhydramnios. In conclusion, long-term amino acid infusions increased renal angiotensinogen gene expression, kidney weight, and distal nephron sodium reabsorptive capacity but failed to restore proximal and total glomerulotubular balance.

fetus; renal function

This article has been cited by other articles:

				A. E. Brandon, A. C. Boyce, E. R. Lumbers, and K. J. Gibson Maternal renal dysfunction in sheep is associated with salt insensitivity in female offspring J. Physiol., January 1, 2009; 587(1): 261 - 270. [Abstract] [Full Text] [PDF]

				K. J. Gibson, A. C. Boyce, B. M. Karime, and E. R. Lumbers Maternal renal insufficiency alters plasma composition and renal function in the fetal sheep Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2007; 292(3): R1204 - R1211. [Abstract] [Full Text] [PDF]