IOVS British Journal of Pharmacology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Originally published In Press as doi:10.1167/iovs.08-1854 on May 23, 2008
 (Investigative Ophthalmology and Visual Science. 2008;49:5503-5509.)
© 2008 by The Association for Research in Vision and Ophthalmology, Inc.
DOI:  10.1167/iovs.08-1854
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
iovs.08-1854v1
49/12/5503    most recent
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Kisilevsky, M.
Right arrow Articles by Hudson, C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Kisilevsky, M.
Right arrow Articles by Hudson, C.

Retinal Arteriolar and Middle Cerebral Artery Responses to Combined Hypercarbic/Hyperoxic Stimuli

Mila Kisilevsky,1 Alexandra Mardimae,2 Marat Slessarev,2 Jay Han,2 Joseph Fisher,2 and Chris Hudson1,3

1From the Departments of Ophthalmology and Vision Science and 2Anesthesiology, University of Toronto, Toronto, Ontario, Canada; and the 3School of Optometry, University of Waterloo, Waterloo, Ontario, Canada.

PURPOSE. The relative effect of simultaneously administered oxygen and carbon dioxide on the retinal and cerebral vessels is still controversial. The purpose of this study was to quantify and compare the superior-temporal retinal arteriole (RA) and middle cerebral artery (MCA) responses to hypercarbic and combined hypercarbic/hyperoxic stimuli.

METHODS. Twelve young, healthy volunteers participated in the study. End-tidal pressure of carbon dioxide was raised and maintained at 22% from baseline (hypercarbia), while end-tidal pressures of oxygen (PETO2) of 100 (normoxia), 500, and 300 mm Hg (hyperoxia) were instituted. RA diameter and blood velocity were measured with laser Doppler velocimetry and simultaneous vessel densitometry; MCA blood velocity was measured with transcranial Doppler ultrasound.

RESULTS. Normoxic hypercarbia increased RA blood velocity by +17% and calculated flow by +21%. Hypercarbia/hyperoxia-500 mm Hg decreased RA diameter by –8%, velocity by –16% and calculated flow by –29%. MCA blood velocity increased by +45% in response to normoxic hypercarbia, significantly greater than RA blood velocity (P < 0.001). Increase in PETO2 did not affect the hypercarbia-induced increase in MCA blood velocity.

CONCLUSIONS. Hyperoxia reversed hypercarbia-induced vasodilation in RA in a concentration-dependent manner. Hypercarbia induced greater vasodilation in the MCA than in the RA but MCA blood velocity was unaffected by increases in PETO2.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2008 by the Association for Research in Vision and Ophthalmology