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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
biochemistry, genetics and molecular biology
Jugular venous pooling during lowering of the head affects blood pressure of the anesthetized giraffe
American Journal of Physiology - Regulatory Integrative and Comparative Physiology, Volume 297, No. 4, Year 2009
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Description
How blood flow and pressure to the giraffe's brain are regulated when drinking remains debated. We measured simultaneous blood flow, pressure, and cross-sectional area in the carotid artery and jugular vein of five anesthetized and spontaneously breathing giraffes. The giraffes were suspended in the upright position so that we could lower the head. In the upright position, mean arterial pressure (MAP) was 193 ± 11 mmHg (mean ± SE), carotid flow was 0.7 ± 0.2 l/min, and carotid cross-sectional area was 0.85 ± 0.04 cm2. Central venous pressure (CVP) was 4 ± 2 mmHg, jugular flow was 0.7 ± 0.2 l/min, and jugular cross-sectional area was 0.14 ± 0.04 cm2 (n = 4). Carotid arterial and jugular venous pressures at head level were 118 ± 9 and -7 ± 4 mmHg, respectively. When the head was lowered, MAP decreased to 131 ± 13 mmHg, while carotid cross-sectional area and flow remained unchanged. Cardiac output was reduced by 30%, CVP decreased to -1 ± 2 mmHg (P < 0.01), and jugular flow ceased as the jugular cross-sectional area increased to 3.2 ± 0.6 cm2 (P < 0.01), corresponding to accumulation of ∼1.2 l of blood in the veins. When the head was raised, the jugular veins collapsed and blood was returned to the central circulation, and CVP and cardiac output were restored. The results demonstrate that in the upright-positioned, anesthetized giraffe cerebral blood flow is governed by arterial pressure without support of a siphon mechanism and that when the head is lowered, blood accumulates in the vein, affecting MAP. Copyright © 2009 the American Physiological Society.
Authors & Co-Authors
Brøndum, Emil T.
Denmark, Aarhus
Aarhus Universitet
Hasenkam, J. Michael
Denmark, Aarhus
Aarhus Universitet
Secher, Niels H.
Denmark, Copenhagen
Rigshospitalet
Bertelsen, Mads F.
Denmark, Copenhagen
Københavns Universitet
Denmark, Frederiksberg
Copenhagen Zoo
Grøndahl, Carsten
Denmark, Frederiksberg
Copenhagen Zoo
Petersen, K. K.
Denmark, Aarhus
Aarhus Universitetshospital
Buhl, R.
Denmark, Copenhagen
Københavns Universitet
Aalkjær, Christian
Denmark, Aarhus
Aarhus Universitet
Baandrup, Ulrik Thorngren
Denmark, Aarhus
Aarhus Universitetshospital
Denmark, Hjorring
Sygehus Vendsyssel - Hjørring
Nygaard, H.
Denmark, Aarhus
Aarhus Universitet
Smerup, Morten Holdgaard
Denmark, Aarhus
Aarhus Universitet
Stegmann, George F.
South Africa, Pretoria
University of Pretoria
Sloth, Erik
Denmark, Aarhus
Aarhus Universitet
Østergaard, Kristine Hovkjær
Denmark, Hjorring
Sygehus Vendsyssel - Hjørring
Nissen, P.
Denmark, Copenhagen
Rigshospitalet
Runge, M.
Denmark, Copenhagen
Rigshospitalet
Pitsillides, K.
United States, Sacramento
Endosomatic Technologies Llc
Wang, Tobias S.
Denmark, Aarhus
Aarhus Universitet
Statistics
Citations: 62
Authors: 18
Affiliations: 8
Identifiers
Doi:
10.1152/ajpregu.90804.2008
ISSN:
03636119
Research Areas
Noncommunicable Diseases
Study Design
Cross Sectional Study