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Matched increases in cerebral artery shear stress, irrespective of stimulus, induce similar changes in extra-cranial arterial diameter in humans.

Smith, KJ, Hoiland, RL, Grove, R, McKirdy, H, Naylor, L, Ainslie, PN and Green, DJ (2017) Matched increases in cerebral artery shear stress, irrespective of stimulus, induce similar changes in extra-cranial arterial diameter in humans. Journal of Cerebral Blood Flow & Metabolism. ISSN 0271-678X

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Abstract

The mechanistic role of arterial shear stress in the regulation of cerebrovascular responses to physiological stimuli (exercise and hypercapnia) is poorly understood. We hypothesised that, if shear stress is a key regulator of arterial dilation, then matched increases in shear, induced by distinct physiological stimuli, would trigger similar dilation of the large extra-cranial arteries. Participants ( n = 10) participated in three 30-min experimental interventions, each separated by ≥48 h: (1) mild-hypercapnia (FICO2:∼0.045); (2) submaximal cycling (EX; 60%HRreserve); or (3) resting (time-matched control, CTRL). Blood flow, diameter, and shear rate were assessed (via Duplex ultrasound) in the internal carotid and vertebral arteries (ICA, VA) at baseline, during and following the interventions. Hypercapnia and EX produced similar elevations in blood flow and shear rate through the ICA and VA ( p < 0.001), which were both greater than CTRL. Vasodilation of ICA and VA diameter in response to hypercapnia (5.3 ± 0.8 and 4.4 ± 2.0%) and EX (4.7 ± 0.7 and 4.7 ± 2.2%) were similar, and greater than CTRL ( p < 0.001). Our findings indicate that matched levels of shear, irrespective of their driving stimulus, induce similar extra-cranial artery dilation. We demonstrate, for the first time in humans, an important mechanistic role for the endothelium in regulating cerebrovascular response to common physiological stimuli in vivo.

Item Type: Article
Uncontrolled Keywords: 1103 Clinical Sciences, 1109 Neurosciences, 1102 Cardiovascular Medicine And Haematology
Subjects: R Medicine > RC Internal medicine > RC1200 Sports Medicine
Divisions: Sport & Exercise Sciences
Publisher: SAGE Publications
Related URLs:
Date Deposited: 20 Dec 2017 11:30
Last Modified: 20 Sep 2018 03:49
DOI or Identification number: 10.1177/0271678X17739220
URI: http://researchonline.ljmu.ac.uk/id/eprint/7738

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