Mechanisms of neonatal increase in glomerular filtration rate

Anita J. Turner, Russell D. Brown, Mattias Carlström, Karen J. Gibson, A. Erik G Persson

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

To investigate the mechanisms responsible for the neonatal increase in glomerular filtration rate (GFR), renal function studies (whole kidney and micropuncture) were carried out in anesthesized fetal sheep (133-140 days gestation; term = 150 days) and lambs (12-18 days). Fetuses were delivered and placed in a water bath (39.5°C), keeping the umbilical cord moist and intact. Lambs were studied on a thermostatically controlled heating pad. Animals were prepared for either blood flow studies or micropuncture measurements. Expected differences in blood composition and cardiovascular and renal function were observed between fetuses and lambs, and values obtained for most variables were similar to those measured in chronically catheterized unanesthetized animals. Fetal GFR was much lower than that of lambs (0.20 vs. 0.62 ml·min-1·g kidney-1, P < 0.001). Free-flow, stop-flow, and net filtration pressures (NFP) were lower in the fetuses than the lambs (NFP 20.8 vs. 23.8 mmHg, P < 0.001), as was the calculated ultrafiltration coefficient (0.014 vs. 0.022 ml·min -1·g-1·mmHg-1, P < 0.001). Thus, we conclude that rises in both net filtration pressure and the ultrafiltration coefficient contribute to the large increase in GFR between fetal life and ∼2 wk after birth.

Original languageEnglish
Pages (from-to)R916-R921
Number of pages6
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume295
Issue number3
DOIs
Publication statusPublished - Sep 2008
Externally publishedYes

Keywords

  • Fetus
  • Free-flow pressure
  • Lamb
  • Micropuncture
  • Stop-flow pressure

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