Autoregulation of afferent arteriolar blood flow in juxtamedullary nephrons

Tsuneo Takenaka, Lisa M. Harrison-Bernard, Edward W. Inscho, Pamela K Carmines, L. Gabriel Navar

Research output: Contribution to journalArticle

85 Scopus citations

Abstract

Utilizing the in vitro blood-perfused juxtamedullary nephron preparation, we examined the effects of alterations in renal arterial pressure on afferent arteriolar blood flow. With video microscopy and cross-correlation techniques, arteriolar inside diameters and centerline erythrocyte velocity were measured to estimate single afferent arteriolar blood flow. In response to random changes in perfusion pressure, afferent arteriolar diameter (n = 8) varied inversely (-0.53 ± 0.02%/mmHg), and erythrocyte velocity was directly related (1.4 ± 0.1%/mmHg). Above 95 mmHg, the slope of the relationship between perfusion pressure and afferent arteriolar blood flow did not differ from zero (0.081 ± 0.053%/mmHg), suggesting efficient autoregulation. When the tubuloglomerular feedback pathway was interrupted by the addition of furosemide (n = 9) or papillectomy (n = 7), there was attenuation of pressure-induced afferent arteriolar constriction, with impairment in blood flow autoregulation (0.60 ± 0.05%/mmHg). Superfusion with diltiazem abolished autoregulatory responses in afferent arteriolar diameter and blood flow (1.5 ± 0.2%/mmHg). These data demonstrate the autoregulation of blood flow of individual afferent arterioles in juxtamedullary nephrons and suggest that both tubulo-glomerular feedback-dependent and -independent mechanisms are required for autoregulatory responses.

Original languageEnglish (US)
Pages (from-to)F879-F887
JournalAmerican Journal of Physiology - Renal Fluid and Electrolyte Physiology
Volume267
Issue number5 36-5
Publication statusPublished - Jan 1 1994

    Fingerprint

Keywords

  • afferent arteriolar diameter
  • erythrocyte velocity
  • glomerular blood flow
  • myogenic response
  • tubuloglomerular feedback

ASJC Scopus subject areas

  • Physiology

Cite this