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March 1, 1990AJP Renal Physiology

Autoregulation and tubuloglomerular feedback in juxtamedullary glomerular arterioles

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Population

Rat juxtamedullary nephrons in vitro

Comparison

Increase in blood perfusion pressure, TGF… vs Baseline conditions

Design

Preclinical

Authors

DCDaniel CasellasUniversity of AlabamaLML. C. MooreCalifornia Institute of Technology

Discussion

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Implication

Findings from this isolated preparation should not yet inform practice; extends mechanistic understanding of autoregulation and TGF in juxtamedullary nephrons.

Key Points

  • To identify the specific arteriolar sites mediating renal autoregulatory vasoconstriction and tubuloglomerular feedback responses in juxtamedullary nephrons.
  • Measured arteriolar lumen diameters using high-contrast shadow-cast videometry in blood-perfused rat juxtamedullary nephrons in vitro across perfusion pressures of 60 to 140 mmHg.
  • Stimulated tubuloglomerular feedback via microinjection of Ringer solution into the cortical thick ascending limb with or without 0.1 mM furosemide, and tested L-type calcium channel inhibition with 1 µM nimodipine.
  • Increasing perfusion pressure from 60 to 140 mmHg caused significant vasoconstriction in terminal afferent arterioles (40 ± 4% luminal reduction) and mid-to-late afferent arterioles (23 ± 4% reduction), whereas efferent arterioles showed no change.
  • Direct tubuloglomerular feedback activation reduced terminal afferent arteriolar diameter by 34 ± 5%, a response completely abolished by 0.1 mM furosemide.
  • Superfusion with 1 µM nimodipine provoked pressure-dependent afferent vasodilation and completely abolished autoregulatory constriction without altering efferent arteriolar diameter.

Structured PICO

P
Population
Rat juxtamedullary nephrons in vitro
I
Intervention
Increase in blood perfusion pressure (60 to 140 mmHg), TGF excitation by microinjection of Ringer solution, addition of furosemide (0.1 mM), and calcium channel blockade with nimodipine (1 microM)
C
Comparator
Baseline conditions
O
Outcome
Changes in vessel lumen diameters of early efferent arterioles (EA), mid-to-late afferent arterioles (MAA), and terminal, juxtaglomerular afferent arterioles (JAA)surrogate

The distal afferent arteriole in juxtamedullary nephrons is a major effector site for both renal autoregulation and tubuloglomerular feedback.

Cite This Study

Casellas et al. (1990) studied this question.

synapsesocial.com/papers/6a753c2c0081fe7b05dc0d5chttps://doi.org/10.1152/ajprenal.1990.258.3.f660
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Also Consider

Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context:

  1. 1Theoretical assessment of renal autoregulatory mechanisms2014 · 51 citations
  2. 2Renal autoregulation: perspectives from whole kidney and single nephron studies1978 · 185 citations
  3. 3Dynamic interaction between myogenic and TGF mechanisms in afferent arteriolar blood flow autoregulation2000 · 89 citations
  4. 4Renal Autoregulation in Health and Disease2015 · 495 citations
  5. 5Inter-Relationship between Autoregulation of Glomerular Filtration Rate, Tubuloglomerular Feedback and Juxtaglomerular Renin Activity in Normotensive and Hypertensive Rats1976 · 4 citations