Noradrenergic constriction of cerebral arteries as detected by transcranial doppler (TCD) in the rabbit

Roatta, Silvestro; Canova, Daniela; Bosone, Daniele; Micieli, Giuseppe; Passatore, Magda

doi:10.1016/s0301-5629(03)00977-3

Cited by 5 publications

(2 citation statements)

References 32 publications

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“…From the present study, however, it cannot be determined whether the cerebrovascular responses in the distribution of the MCA reflect global cerebral effects; e.g. discreet regions of the brain may respond differently to changes in sympathetic stimulation (Sercombe et al 1975; Roatta et al 2003). The novel approach in the present study is the use of a Doppler flow index in order to account for any changes in the cross‐sectional area of the MCA.…”

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confidence: 78%

Differential responses to CO₂ and sympathetic stimulation in the cerebral and femoral circulations in humans

Ainslie

Ashmead

Ide

et al. 2005

The Journal of Physiology

118

111

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The relative importance of CO 2 and sympathetic stimulation in the regulation of cerebral and peripheral vasculatures has not been previously studied in humans. We investigated the effect of sympathetic activation, produced by isometric handgrip (HG) exercise, on cerebral and femoral vasculatures during periods of isocapnia and hypercapnia. In 14 healthy males (28.1 ± 3.7 (mean ± S.D.) years), we measured flow velocity (V P ; transcranial Doppler ultrasound) in the middle cerebral artery during euoxic isocapnia (ISO, +1 mmHg above rest) and two levels of euoxic hypercapnia (HC5, end-tidal P CO 2 , P ET,CO 2 , = +5 mmHg above ISO; HC10, P ET,CO 2 = +10 above ISO). Each P ET,CO 2 level was maintained for 10 min using the dynamic end-tidal forcing technique, during which increases in sympathetic activity were elicited by a 2-min HG at 30% of maximal voluntary contraction. Femoral blood flow (FBF; Doppler ultrasound), muscle sympathetic nerve activity (MSNA; microneurography) and mean arterial pressure (MAP; Portapres) were also measured. Hypercapnia increasedV P and FBF by 5.0 and 0.6% mmHg −1 , respectively, and MSNA by 20-220%. Isometric HG increased MSNA by 50% and MAP by 20%, with no differences between ISO, HC5 and HC10. During the ISO HG there was an increase in cerebral vascular resistance (CVR; 20 ± 11%), whileV P remained unchanged. During HC5 and HC10 HG,V P increased (13% and 14%, respectively), but CVR was unchanged. In contrast, HG-induced sympathetic stimulation increased femoral vascular resistance (FVR) during ISO, HC5 and HC10 (17-41%), while there was a general decrease in FBF below ISO. The HG-induced increases in MSNA were associated with increases in FVR in all conditions (r = 0.76-0.87), whereas increases in MSNA were associated with increases in CVR only during ISO (r = 0.91). In summary, in the absence of hypercapnia, HG exercise caused cerebral vasoconstriction, myogenically and/or neurally, which was reflected by increases in CVR and a maintainedV P . In contrast, HG increased FVR during conditions of ISO, HC5 and HC10. Therefore, the cerebral circulation is more responsive to alterations in P CO 2 , and less responsive to sympathetic stimulation than the femoral circulation.

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confidence: 78%

Differential responses to CO₂ and sympathetic stimulation in the cerebral and femoral circulations in humans

Ainslie

Ashmead

Ide

et al. 2005

The Journal of Physiology

118

111

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“…Moreover, previous studies have found less adrenergic nerve density in small cerebral arterioles than in large ones and have demonstrated that the adrenergic receptor-mediated vasoconstriction preferentially affects large cerebral arteries, whereas ␤-adrenergic receptormediated vasodilatation occurs mainly in small cerebral vessels (1,5,6,22). Thus the sympathetic stimulation causes transient large cerebral artery constriction and small artery dilatation (6,50). We propose that CPT, especially in the first minute, may affect small arteries more than large cerebral arteries, and therefore CVR transiently decreases during the initial period of CPT, as shown in our study with no change in RC of RCCA, because the vasodilatation of small arteries or arterioles was more dominant than large artery vasoconstriction in brain.…”

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confidence: 99%

Effects of acute cold exposure on carotid and femoral wave intensity indexes: evidence for reflection coefficient as a measure of distal vascular resistance

Liu

Yuan

Zhang

et al. 2011

Journal of Applied Physiology

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Our aim was to investigate the effects of acute cold pressor test (CPT) on augmentation index (AI) and wave intensity (WI) indexes from right common carotid artery (RCCA) and right common femoral artery (RCFA) and to test whether the reflection coefficient (RC) from wave intensity analysis can reflect the distal vascular resistance (DVR) accurately. Forty-three healthy males were randomly selected for measurements at baseline and 1 min after CPT at RCCA or RCFA. CPT induced similar increases of heart rate and blood pressure in RCCA and RCFA groups with their pulse pressures unchanged. The W(2) (the second peak of WI) was too obscure in RCFA to be analyzed. The W(1) (the first peak of WI) of both arteries, W(1)-W(2) (interval between W(1) and W(2)), and NA (negative area between W(1) and W(2), indicating reflected waves) of RCCA and the R-W(1) (interval between the R wave of ECG and W(1)) of RCFA decreased obviously, whereas the W(2) and R-W(1) of RCCA and the RC (calculated as NA/W(1)) of RCFA increased with no changes in the RC of RCCA and the NA of RCFA during CPT compared with baseline. The AIs from both arteries increased significantly after CPT. These results suggested that acute CPT has opposing effects on cerebral and peripheral vascular resistances, with the former decreased and the latter increased. The RCs from RCCA and RCFA are more associated with the changes of cerebral and peripheral vascular resistances, respectively, than the NA and AI, and the RC is of guiding value in assessing DVR.

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Subthalamic stimulation improves the cerebral hemodynamic response to the cold pressure test in patients with Parkinson's disease

Rätsep

Asser

2012

J of Clinical Ultrasound

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Noradrenergic constriction of cerebral arteries as detected by transcranial doppler (TCD) in the rabbit

Cited by 5 publications

References 32 publications

Differential responses to CO₂ and sympathetic stimulation in the cerebral and femoral circulations in humans

Differential responses to CO₂ and sympathetic stimulation in the cerebral and femoral circulations in humans

Effects of acute cold exposure on carotid and femoral wave intensity indexes: evidence for reflection coefficient as a measure of distal vascular resistance

Subthalamic stimulation improves the cerebral hemodynamic response to the cold pressure test in patients with Parkinson's disease

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Noradrenergic constriction of cerebral arteries as detected by transcranial doppler (TCD) in the rabbit

Cited by 5 publications

References 32 publications

Differential responses to CO2 and sympathetic stimulation in the cerebral and femoral circulations in humans

Differential responses to CO2 and sympathetic stimulation in the cerebral and femoral circulations in humans

Effects of acute cold exposure on carotid and femoral wave intensity indexes: evidence for reflection coefficient as a measure of distal vascular resistance

Subthalamic stimulation improves the cerebral hemodynamic response to the cold pressure test in patients with Parkinson's disease

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Differential responses to CO₂ and sympathetic stimulation in the cerebral and femoral circulations in humans

Differential responses to CO₂ and sympathetic stimulation in the cerebral and femoral circulations in humans