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Choroidal blood flow in pigeons compensates for decreases in arterial blood pressure

A Reiner1, Y Zagvazdin, Malinda E C Fitzgerald

  • 1Department of Anatomy and Neurobiology, College of Medicine, Health Science Center, University of Tennessee, 855 Monroe Avenue, Memphis, TN 38163, USA. areiner@utmem.edu

Experimental Eye Research
|February 8, 2003
PubMed

Insights

Choroidal blood flow (ChBF) in pigeons compensates for arterial blood pressure (ABP) declines, remaining stable within a physiological range. This suggests a common ocular mechanism across warm-blooded vertebrates.

Area of Science:

  • Ophthalmology
  • Comparative Physiology
  • Ocular Circulation

Background:

  • Previous research indicated choroidal blood flow (ChBF) might not regulate against perfusion pressure changes.
  • Recent studies in rabbits and humans demonstrate ChBF compensates for arterial blood pressure (ABP) fluctuations, maintaining stability.
  • The regulatory capacity of ChBF in avian species remained largely unexplored.

Purpose of the Study:

  • To investigate if avian choroidal blood flow (ChBF) compensates for decreases in arterial blood pressure (ABP).
  • To determine if spontaneous or induced reductions in ABP affect ChBF stability in pigeons.
  • To compare avian ChBF autoregulation with mechanisms observed in mammals.

Main Methods:

  • Continuous monitoring of choroidal blood flow (ChBF) using laser Doppler flowmetry in anesthetized pigeons.
  • Simultaneous measurement of arterial blood pressure (ABP) via the brachial artery.
  • Analysis of ChBF and ABP during spontaneous fluctuations and acute blood withdrawal.

Main Results:

  • Choroidal blood flow (ChBF) remained stable as arterial blood pressure (ABP) decreased from baseline to approximately 55 mmHg.
  • Below 50 mmHg, ChBF began to follow ABP linearly, indicating a loss of autoregulation.
  • No compensation was observed when ABP dropped below 40 mmHg; compensation was faster for smaller ABP declines.

Conclusions:

  • Avian choroidal blood flow (ChBF) exhibits autoregulation, compensating for arterial blood pressure (ABP) declines within a physiological range, similar to mammals.
  • This compensatory mechanism in pigeons suggests a conserved ocular response to blood pressure changes across diverse warm-blooded vertebrates.
  • The findings highlight a potentially widespread evolutionary adaptation for maintaining ocular perfusion.

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