Projects per year
Abstract
Evidence for shear stress as a regulator of carotid artery dilation in response to increased arterial carbon dioxide was recently demonstrated in humans during sustained elevations in CO2 (hypercapnia); however, the relative contributions of CO2 and shear stress to this response remains unclear. We examined the hypothesis that, following a 30-second transient increase in arterial CO2 tension and consequent increase in internal carotid artery shear stress, internal carotid artery diameter would increase, indicating shear-mediated dilation, in the absence of concurrent hypercapnia. In 27 healthy participants the partial pressures of end-tidal O2 and CO2, ventilation (pneumotachography), blood pressure (finger-photoplethysmography), heart-rate (electrocardiogram), internal carotid artery flow, diameter and shear stress (high resolution duplex ultrasound) and middle cerebral artery blood velocity (transcranial Doppler) were measured during 4-minute steady state and transient 30-second hypercapnic tests (both +9mmHg CO2). Internal carotid artery dilation was lower in the transient, compared to the steady state hypercapnia (3.3±1.9% vs. 5.3±2.9%, respectively; P<0.03). Increases in internal carotid artery shear stress preceded increases in diameter in both the transient (time: 16.8±13.2s vs. 59.4±60.3s; P<0.01) and steady state (time: 18.2±14.2s vs. 110.3±79.6s; P<0.01) tests. Internal carotid artery dilation was positively correlated with shear rate area under the curve in the transient (r(2)=0.44; P<0.01), but not steady state (r(2)=0.02; P=0.53) trial. Collectively, these results suggest that hypercapnia induces shear-mediated dilation of the internal carotid artery in humans. This study further promotes the application and development of hypercapnia as a clinical strategy for the assessment of cerebrovascular vasodilatory function and health in humans.
Original language | English |
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Article number | ajpheart.00119.2017 |
Pages (from-to) | H24-H31 |
Journal | American Journal of Physiology: Heart and Circulatory Physiology |
Volume | 313 |
Issue number | 1 |
DOIs | |
Publication status | Published - 1 Jul 2017 |
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Dive into the research topics of 'SHEAR-MEDIATED DILATION OF THE INTERNAL CAROTID ARTERY OCCURS INDEPENDENT OF HYPERCAPNIA'. Together they form a unique fingerprint.Projects
- 3 Finished
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Personalised Exercise as Medicine - Optimising the Prescription to Maximise the Benefit
Green, D. (Investigator 01)
NHMRC National Health and Medical Research Council
1/01/15 → 31/12/20
Project: Research
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Healthy Vascular Aging in Humans - Defining the Direct Effects of Exercise on Arterial Adaptation
Green, D. (Investigator 01)
ARC Australian Research Council
1/01/13 → 31/12/16
Project: Research
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Does Manipulation of Arterial Shear Stress Enhance Cerebrovascular Function and Cognition in the Aging Brain
Green, D. (Investigator 01), Lautenschlager, N. (Investigator 02), Cox, K. (Investigator 03), Badcock, J. (Investigator 04) & Pestell, C. (Investigator 05)
NHMRC National Health and Medical Research Council
1/01/13 → 31/12/16
Project: Research