Shear-mediated dilation of the internal carotid artery occurs independent of hypercapnia

Hoiland, Ryan L.; Smith, Kurt J.; Carter, Howard; Lewis, Nia C. S.; Tymko, Michael M.; Wildfong, Kevin W.; Bain, Anthony R.; Green, Daniel; Ainslie, Philip N.

doi:10.1152/ajpheart.00119.2017

Cited by 58 publications

(110 citation statements)

References 49 publications

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“…However, in response to the CPT, females demonstrated a reduced relative CCA response compared with males, despite having a higher CCA mean shear rate, which promotes smooth muscle relaxation (i.e. vasodilatation) via nitric oxide release (Green, Dawson, Groenewoud, Jones, & Thijssen, ) and might influence the diameter of the carotid arteries (Carter et al., ; Hoiland et al., ). This finding also indicates that females have a reduced nitric oxide‐dependent dilatation of the CCA compared with males during the CPT; however, given that the blood pressure responses between males and females were different, further investigation is required to elucidate these shear‐mediated mechanism(s) adequately.…”

Section: Discussionmentioning

confidence: 99%

Sex differences in the circulatory responses to an isocapnic cold pressor test

Stone

Ainslie

Kerstens

et al. 2019

Experimental Physiology

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New Findings What is the central question of this study?Do sex differences exist in the cardiorespiratory responses to an isocapnic cold pressor test (CPT)? What is the main finding and its importance?During the CPT, there were no sex differences in the respiratory response; however, females demonstrated a reduced mean arterial pressure and reduced dilatation of the common carotid artery. Given that the CPT is predictive of future cardiovascular events, these data have clinical implications for improving the utility of the CPT to determine cardiovascular health risk. Sex differences should be taken into consideration when conducting and interpreting a CPT. Abstract The cold pressor test (CPT) elicits a transient increase in sympathetic nervous activity, minute ventilation (V̇E), mean arterial pressure (MAP) and common carotid artery (CCA) diameter in healthy individuals. Although the extent of dilatation of the CCA in response to the CPT has been used as a clinical indicator of cardiovascular health status, the potential sex differences have yet to be explored. In response to a CPT, we hypothesized that elevations in V̇E and MAP and dilatation of the CCA would be attenuated in females compared with males. In 20 young, healthy participants (10 females), we measured the respiratory, cardiovascular and CCA responses during a CPT, which consisted of a 3 min immersion of the right foot into 0–1 ice water. Blood pressure (via finger photoplethysmography), heart rate (via electrocardiogram) and CCA diameter and velocity (via Duplex ultrasound) were simultaneously recorded immediately before and during the CPT. During the CPT, while controlling end‐tidal gases to baseline values, the main findings were as follows: (i) no sex differences were present in absolute or relative changes in V̇E (P = 0.801 and P = 0.179, respectively); (ii) the relative MAP and CCA diameter response were reduced in females by 51 and 55%, respectively (P = 0.008 and P = 0.029 versus males, respectively); and (iii) the relative MAP responses was positively correlated with the dilatation of the CCA in males (r = 0.42, P = 0.019), in females (r = 0.43, P = 0.019) and in males and females combined (r = 0.55, P < 0.001). Given that the CPT is used as a clinical tool to assess cardiovascular health status, sex differences should be considered in future studies.

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Section: Discussionmentioning

confidence: 99%

Sex differences in the circulatory responses to an isocapnic cold pressor test

Stone

Ainslie

Kerstens

et al. 2019

Experimental Physiology

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“…Finally, elevations of CBF during hypercapnia may be facilitated by the dilation of upper‐stream extracranial arteries via shear‐stress mediated release of endothelium‐derived vasodilatory agents (Hoiland et al . ).…”

Section: Main Determinants Of Cbfmentioning

confidence: 97%

Cerebral blood flow in normal aging adults: cardiovascular determinants, clinical implications, and aerobic fitness

Tarumi

Zhang

2017

Journal of Neurochemistry

203

142

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Senescence is a leading cause of mortality, disability, and noncommunicable chronic diseases in older adults. Mounting evidence indicates that the presence of cardiovascular disease and risk factors elevates the incidence of both vascular cognitive impairment and Alzheimer's disease (AD). Age-related declines in cardiovascular function may impair cerebral blood flow (CBF) regulation, leading to the disruption of neuronal micro-environmental homeostasis. The brain is the most metabolically active organ with limited intracellular energy storage and critically depends on CBF to sustain neuronal metabolism. In patients with AD, cerebral hypoperfusion, increased CBF pulsatility, and impaired blood pressure control during orthostatic stress have been reported, indicating exaggerated, age-related decline in both cerebro-and cardiovascular function. Currently, AD lacks effective treatments; therefore, the development of preventive strategy is urgently needed. Regular aerobic exercise improves cardiovascular function, which in turn may lead to a better CBF regulation, thus reducing the dementia risk. In this review, we discuss the effects of aging on cardiovascular regulation of CBF and provide new insights into the vascular mechanisms of cognitive impairment and potential effects of aerobic exercise training on CBF regulation.

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“…Recent elegant studies (Carter et al, ; Hoiland et al, ) have proved that shear rate (SR) contributes to the dilation in the internal carotid artery (ICA) during hypercapnia, and this shear‐mediated dilation of ICA occurs independently of sustained in hypercapnia. Therefore, as with the peripheral conduit arteries, SR plays a key role in carotid artery vasodilatation (Hoiland et al, ; Smith et al, ). The hypercapnia‐induced shear‐mediated dilation in the ICA as a cerebrovascular FMD has been used for the characterization of cerebrovascular endothelial function in previous studies (Carter et al, ; Hoiland et al, ; Iwamoto, Bock, & Casey, , b; Smith et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, as with the peripheral conduit arteries, SR plays a key role in carotid artery vasodilatation (Hoiland et al, ; Smith et al, ). The hypercapnia‐induced shear‐mediated dilation in the ICA as a cerebrovascular FMD has been used for the characterization of cerebrovascular endothelial function in previous studies (Carter et al, ; Hoiland et al, ; Iwamoto, Bock, & Casey, , b; Smith et al, ). In addition to measure peripheral FMD, here, to test this hypothesis, we assessed the cerebrovascular FMD using this new technique in young smokers and nonsmokers.…”

Section: Introductionmentioning

confidence: 99%

Habitual cigarette smoking attenuates shear‐mediated dilation in the brachial artery but not in the carotid artery in young adults

et al. 2020

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In the present study, we hypothesized that habitual cigarette smoking attenuates endothelial function in the cerebral circulation as well as that of the peripheral circulation in young adults. To test this hypothesis, we measured cerebrovascular and peripheral flow‐mediated dilation (FMD) in young smokers and nonsmokers in the present study. Ten healthy nonsmokers and 10 smokers participated in the study. We measured blood velocity and diameter in the brachial artery and internal carotid artery (ICA) using Doppler ultrasound. We identified shear‐mediated dilation in the brachial artery and ICA by the percentage change in peak diameter during hyperemia stimulation (reactive hyperemia and hypercapnia). We measured the baseline diameter and the shear rate area under the curve from the onset of hyperemia to peak dilation in the brachial artery and ICA, finding the measurements of the smokers and those of the nonsmokers did not differ (p > .05). In contrast to brachial FMD (5.07 ± 1.79% vs. 7.92 ± 3.01%; smokers vs. nonsmokers, p = .019), FMD in the ICA was not attenuated in the smokers compared with that of the nonsmokers (5.46 ± 2.32% vs. 4.57 ± 2.70%; p = .442). These findings indicate that in young healthy smokers, cerebral endothelial function was preserved, and the response of cerebral endothelial function to smoking was different from that of peripheral vasculature.

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Shear-mediated dilation of the internal carotid artery occurs independent of hypercapnia

Cited by 58 publications

References 49 publications

Sex differences in the circulatory responses to an isocapnic cold pressor test

Sex differences in the circulatory responses to an isocapnic cold pressor test

Cerebral blood flow in normal aging adults: cardiovascular determinants, clinical implications, and aerobic fitness

Habitual cigarette smoking attenuates shear‐mediated dilation in the brachial artery but not in the carotid artery in young adults

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