The optimal design of vascular networks maximizes circulatory efficiency while minimizing power costs. We investigated the effects of acute changes in vascular tone on retinal arteriolar network geometry. Six hypertensive and six normotensive subjects each breathed air, 5% CO2 (with 12% O2), and 100% O2 for 5 min periods in random order. Retinal photographs were taken at the end of each test period. Bifurcation angles and arteriolar diameters were measured using operator-directed image analysis, and junction exponents were calculated. Arteriolar diameters narrowed on breathing O2. The magnitude of this change was significantly greater in normotensive than in hypertensive subjects. Angles narrowed in normotensive subjects, but not significantly in hypertensive subjects. Arteriolar diameters increased significantly on breathing CO2 in normotensive but not in hypertensive subjects, but there were no changes in angles. Despite changes in diameter, junction exponents did not change under any conditions. Vascular reactivity in the retinal arteriolar bed appears to be diminished in hypertensive subjects. The failure of junction exponents to change, despite alterations in diameter, suggests that arteriolar diameters at retinal bifurcations adhere to optimality principles when exposed to acute vasoactive stress. As vasoconstriction is associated with the narrowing of bifurcation angles, previous observations showing narrowed angles in hypertensive subjects could be explained by increased tone in the retinal arteriolar bed.
Skip Nav Destination
Article navigation
Research Article|
November 07 2000
Acute effects of oxygen and carbon dioxide on retinal vascular network geometry in hypertensive and normotensive subjects
N. CHAPMAN;
1Department of Clinical Pharmacology, School of Medicine at NHLI, Imperial College of Science, Technology and Medicine, QEQM Wing, St Mary's Hospital, South Wharf Road, London W2 1NY, U.K.
Correspondence: Dr N. Chapman (e-mail n.chapman@ic.ac.uk).
Search for other works by this author on:
G. HAIMES;
G. HAIMES
1Department of Clinical Pharmacology, School of Medicine at NHLI, Imperial College of Science, Technology and Medicine, QEQM Wing, St Mary's Hospital, South Wharf Road, London W2 1NY, U.K.
Search for other works by this author on:
A. V. STANTON;
A. V. STANTON
1Department of Clinical Pharmacology, School of Medicine at NHLI, Imperial College of Science, Technology and Medicine, QEQM Wing, St Mary's Hospital, South Wharf Road, London W2 1NY, U.K.
Search for other works by this author on:
S. A. THOM;
S. A. THOM
1Department of Clinical Pharmacology, School of Medicine at NHLI, Imperial College of Science, Technology and Medicine, QEQM Wing, St Mary's Hospital, South Wharf Road, London W2 1NY, U.K.
Search for other works by this author on:
A. D. HUGHES
A. D. HUGHES
1Department of Clinical Pharmacology, School of Medicine at NHLI, Imperial College of Science, Technology and Medicine, QEQM Wing, St Mary's Hospital, South Wharf Road, London W2 1NY, U.K.
Search for other works by this author on:
Publisher: Portland Press Ltd
Received:
April 11 2000
Revision Received:
June 22 2000
Accepted:
August 01 2000
Online ISSN: 1470-8736
Print ISSN: 0143-5221
The Biochemical Society and the Medical Research Society © 2000
2000
Clin Sci (Lond) (2000) 99 (6): 483–488.
Article history
Received:
April 11 2000
Revision Received:
June 22 2000
Accepted:
August 01 2000
Citation
N. CHAPMAN, G. HAIMES, A. V. STANTON, S. A. THOM, A. D. HUGHES; Acute effects of oxygen and carbon dioxide on retinal vascular network geometry in hypertensive and normotensive subjects. Clin Sci (Lond) 1 December 2000; 99 (6): 483–488. doi: https://doi.org/10.1042/cs0990483
Download citation file:
Sign in
Don't already have an account? Register
Sign in to your personal account
You could not be signed in. Please check your email address / username and password and try again.
Captcha Validation Error. Please try again.