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MedLine Citation:
PMID:  21454250     Owner:  NLM     Status:  Publisher    
The tubuloglomerular feedback mechanism (TGF) plays an important role in regulating single nephron GFR by coupling distal tubular flow to arteriolar tone. It is not known if TGF is active in the developing kidney or whether it can regulate renal vascular tone and thus GFR during intrauterine life. TGF characteristics were examined in late gestation ovine fetuses and lambs under normovolemic and volume-expanded (VE) conditions. Lambs and pregnant ewes were anaesthetized and the fetuses delivered via a caesarean incision into a heated water bath, with the umbilical cord intact. Under normovolemic conditions, mean arterial pressure of the fetuses was lower than lambs (51±1 vs 64±3mmHg). The maximum TGF response (ΔP(SFmax)) was found to be lower in fetuses than lambs when tubular perfusion was increased from 0-40nl/min (5.4±0.7 vs 10.6±0.4mmHg). Furthermore, the flow-rate eliciting half-maximal response (turning point, TP) was 15.7±0.9nl/min in fetuses compared to 19.3±1.0nl/min in lambs, indicating a greater TGF sensitivity of the prenatal kidney. VE decreased ΔP(SFmax) (4.2±0.4mmHg) and increased TP to 23.7±1.3nl/min in lambs. In fetuses, VE increased stop-flow pressure from 26.6±1.5 to 30.3±0.8mmHg, and reset TGF sensitivity so that TP increased to 21.3±0.7nl/min, but had no effect on ΔP(SFmax). This study provides direct evidence that the TGF mechanism is active during fetal life and responds to physiological stimuli. Moreover, reductions in TGF sensitivity may contribute to the increase in GFR at birth.
Russell D Brown; Anita J Turner; Mattias Carlström; A Erik G Persson; Karen Jane Gibson
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-3-30
Journal Detail:
Title:  American journal of physiology. Renal physiology     Volume:  -     ISSN:  1522-1466     ISO Abbreviation:  -     Publication Date:  2011 Mar 
Date Detail:
Created Date:  2011-4-1     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901990     Medline TA:  Am J Physiol Renal Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
1Monash Univesity.
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