The contribution of endogenous vasodilators to the control of glomerular hemodynamics

Shuji Arima, Sadayoshi Ito, Keishi Abe

Research output: Contribution to journalArticle

Abstract

Preglomerular afferent (Af-) and postglomerular efferent arterioles (Ef-Arts) are crucial vascular segments in the control of glomerular hemodynamics. However, their vascular reactivity is not fully understood. We examined 1) their responses to angiotensin II (All) or norepinephrine (NE), and 2) the possible modulatory roles of nitric oxide (NO) and prostaglandins (PGs) in these responses. Rabbit Af-or Ef-Arts were microperfused in vitro. Ef-Arts were perfused in either the orthograde direction from the distal end of Af-Arts through the glomerulus (OP) or the retrograde direction from its distal end to eliminate the influence of the glomerulus (RP). Although All and NE constricted both arterioles in a dose-dependent manner, sensitivity to All was higher in Ef-Arts. All began to cause significant (P<0. 01) constriction from 109 M (11±3%, n = ll) in Af-Arts, and from 10-11 M in Ef-Arts (OP; 11± 4%, n = 9. RP; 10±2%, n = 5). In addition, both All and NE produced stronger constriction of Ef-Arts in RP than OP; All at 10-8 M or NE at 10-6 M decreased the diameter by 35±4% or 25 ±4% in OP and 74±4% or 62±7% in RP. NO synthesis inhibitor nitro-L-arginine (L-NAME; 10-4 M) increased the sensitivity of Af-Art to All without affecting the reactivity of Ef-Art; in L-NAME-pretreated Af-Arts, All began to cause significant constriction from 10-10 M (14 ±4%, n = 9, P<0. 01). Thus, L-NAME-pretreatment significantly decreased the differences in sensitivity to All between Af-and Ef-Arts without affecting different vascular responses between OP and RP. Indomethacin (5xl0-5 M) significantly augmented the All-or NE-induced Ef-Art constriction only in OP; All at 10-8 M or NE at 10-6 M decreased the diameter by 72±5% (n = 8) or 48±3% (n = 7). Thus, indomethacin-pretratment markedly diminished the differences in responses between OP and RP. These results suggest that 1) NO modulates All action only in the Af-Art, contributing to the difference in sensitivity to All between Aland Ef-Art, and 2) the glomerulus controls vascular reactivity of the downstream Ef-Art by releasing PGs.

Original languageEnglish
Pages (from-to)692-701
Number of pages10
JournalThe Japanese Journal Of Nephrology
Volume36
Issue number6
DOIs
Publication statusPublished - 1994 Jan 1

Keywords

  • afferent arteriole
  • efferent arteriole
  • glomerular hemodynamics
  • nitric oxide
  • prostaglandins

ASJC Scopus subject areas

  • Nephrology

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