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Influence of PaO2 on Cerebral Macro- and Microcirculation as Observed by Light Reflection: Time Course of Changes

  • Philip T. Weinbrecht
  • Lance C. Johnson
  • Ian S. Longmuir
  • James A. Knopp
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 200)

Summary

A silicon intensified target camera was used to study cerebral cortical vessels of the cat through a skull window implant, and red cell content changes were measured by light reflectance. Red cell content changes were observed in cerebral arterioles, capillaries, and venules when the PaO2 was decreased by lowering the PiO2.

The time course of change in the diameter of the arterioles and venules was measured by selecting a cross section of the vessel plus some surrounding tissue. From the averaged cross-sectional reflectance signal, the change in vessel diameter was followed as a function of time following the PiO2 change.

All vessels of greater than 10 microns were observed in focus. Substantial areas where no vessels could be discriminated would contain only capillaries, and changes in light reflectance from such areas would indicate changes in capillary red cell content. The time course of these changes following a step decrease in PiO2 was recorded.

Results show that the sequence of red cell content increase in cerebral microcirculation during hypoxia is capillary before venule and arteriole. The times of initial red cell content increase are 37.9 ± 7 s, 59.7 ± 7.9 s, and 60.8 ± 9.1 s, respectively. These results suggest an increase in the capillary bed red cell content as the initial response to hypoxia, but venules and arterioles change only on longer exposure to hypoxia. The sequence of the increase in red cell content suggests the capillaries rather than the arterioles are the vessels which respond to the oxygen autoregulation signal.

Keywords

Light Reflectance Reflectance Signal Tissue Oxygen Tension Reflectance Change Cerebral Microcirculation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    I. S. Longmuir, J. A. Knopp, and J. L. Pittman, Changes in cerebral oxygen tension and red cell content on sensory stimulation, in: “Advances in Experimental Medicine and Biology,” D. Bruley, H. Bicher, and D. Reneau, eds., Vol. 180, pp. 185–190, Plenum Press, New York (1984).Google Scholar
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    D. M. Benson, J. A. Knopp, and I. S. Longmuir, Effect of optical configuration and tissue absorption on the depth of light penetration in light microscopy, Fed. Proc. 40:587 (1981) Abstr.Google Scholar
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    I. S. Longmuir, J. A. Knopp, and P. T. Weinbrecht, Capillary red cell residence as a measure of tissue oxygen delivery, in: “Advances in Experimental Medicine and Biology,” Plenum Press, New York (1986) in press.Google Scholar

Copyright information

© Plenum Press, New York 1986

Authors and Affiliations

  • Philip T. Weinbrecht
    • 1
  • Lance C. Johnson
    • 1
  • Ian S. Longmuir
    • 1
  • James A. Knopp
    • 1
  1. 1.Department of BiochemistryNorth Carolina State UniversityRaleighUSA

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