Changes in cochlear blood flow due to intra-arterial infusions of angiotensin II (3-8) (angiotensin IV) in guinea pigs

John K.M. Coleman, Janet I. Lee, Josef M. Miller, Alfred L. Nuttall

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

The effects of a newly discovered form of angiotensin, angiotensin IV (ANGIV), on cochlear blood flow (CBF) have been investigated utilizing the laser Doppler flowmetry (LDF) technique. Two specific questions were addressed: What are the effects of anterior inferior cerebellar artery infusions (AICA) of ANGIV on CBF and do angiotensin fragments other than ANGIV influence CBF in mature male and female guinea pigs. Infusions of ANGIV, and C-terminal shortened fragments were accomplished via micropipette into the AICA and changes in CBF were observed using LDF. The results demonstrated that 10 and 100 pmol/min doses of ANGIV increased CBF 22% and 75% (n = 6; P < 0.01) from baseline, respectively, with little change in mean arterial blood pressure (MAP). Pretreatment with the ANGIV antagonist divalanal-ANGIV (1 nmole/min) blocked increases in CBF due to infusions of 100 pmol/min of ANGIV. The infusion of the C-terminal shortened fragment ANGIV(1-5) and saline had no significant effect on either CBF or MAP. These results provide the evidence for a new subtype of the angiotensin receptor and indicate the likely role of circulating hormones in blood flow regulation in the inner ear.

Original languageEnglish (US)
Pages (from-to)61-68
Number of pages8
JournalHearing Research
Volume119
Issue number1-2
DOIs
StatePublished - May 1 1998

Keywords

  • Angiotensin
  • Blood flow
  • Cochlea
  • Guinea pig
  • Hearing
  • Microcirculation

ASJC Scopus subject areas

  • Sensory Systems

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