Norepinephrine and Epinephrine Responses during Orthostatic Intolerance in Healthy Elderly Men

Gabbett, Tim J.; Gass, G. C.; Gass, Elizabeth; Morris, Norman; Bennett, Gregory; Thalib, Lukman

doi:10.2170/jjphysiol.50.59

Cited by 10 publications

(8 citation statements)

References 33 publications

(59 reference statements)

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“…baroreflex; arterial pressure; orthostasis; sympathetic nervous system; norepinephrine NORMAL cardiovascular dynamics during orthostasis include the displacement of blood from the central circulation into the lower extremities, reduction of venous return, and decreased stroke volume and cardiac output (10). Arterial pressure (AP) is usually not significantly altered during orthostasis in normal individuals due to rapid baroreflex-mediated increases in heart rate (HR) and sympathetic vasoconstrictor nerve activity (5,22), resulting in increased total peripheral resistance via norepinephrine (NE) secretion (8,10).…”

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confidence: 99%

“…Arterial pressure (AP) is usually not significantly altered during orthostasis in normal individuals due to rapid baroreflex-mediated increases in heart rate (HR) and sympathetic vasoconstrictor nerve activity (5,22), resulting in increased total peripheral resistance via norepinephrine (NE) secretion (8,10). These well-synchronized cardiovascular events prevent major abrupt changes in AP and the development of symptoms during orthostatic stress.…”

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Cardiovascular dynamics in healthy subjects with differing heart rate responses to tilt

Ramírez-Marrero¹,

Charkoudian²,

Hart³

et al. 2008

Journal of Applied Physiology

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MJ. Cardiovascular dynamics in healthy subjects with differing heart rate responses to tilt. J Appl Physiol 105: 1448 -1453, 2008. First published August 28, 2008 doi:10.1152/japplphysiol.90796.2008.-Orthostatic stress such as head-up tilt (HUT) elicits a wide range of heart rate (HR) and arterial pressure (AP) responses among healthy individuals. In this study, we evaluated cardiovascular dynamics in healthy subjects with different HR responses to HUT, but without autonomic dysfunction. We measured AP (brachial artery) and HR (ECG) during 5 min of 60°H UT in 76 healthy normotensive individuals. We then chose individuals on the basis of the extremes of HR responses to HUT (high ϭ ⌬HR Ն 20 beats/min, and low ϭ ⌬HR Յ 10 beats/min; n ϭ 15 per group). Peak HR during HUT was 87 Ϯ 10 beats/min in the high and 69 Ϯ 14 beats/min in the low group (P Ͻ 0.05). High HR responders had lower systolic pressure at baseline (121 Ϯ 9 vs. 129 Ϯ 11 mmHg, P Ͻ 0.05) and during HUT (120 Ϯ 10 vs. 131 Ϯ 13 mmHg, P Ͻ 0.05), and higher plasma norepinephrine (NE) response to HUT (⌬NE: 156.9 Ϯ 17.8 vs. 89.0 Ϯ 17.2 pg/ml; P Ͻ 0.05). ⌬NE during HUT was also significantly correlated with ⌬HR when all 76 subjects were included in a regression analysis (r ϭ 0.39; P Ͻ 0.001). Pulse pressure was lower during HUT in high HR responders compared with low HR responders (45 Ϯ 1 vs. 55 Ϯ 2 mmHg, P Ͻ 0.05). High HR responders also had larger fluctuations in systolic and pulse pressure during HUT (coefficient of variation ϭ 10.7 Ϯ 0.7 vs. 5.7 Ϯ 0.3%; 7.9 Ϯ 0.5 vs. 4.1 Ϯ 0.4%, respectively, P Ͻ 0.05). Sex distribution was different between groups (high: 5 women, 10 men; low: 10 women, 5 men). Higher HR with lower AP during HUT is consistent with normal baroreflex mechanisms of integration. Although interindividual variability appears to be a fundamental part of cardiovascular regulation, the mechanisms of these differences and the sex discrepancy requires further investigation. baroreflex; arterial pressure; orthostasis; sympathetic nervous system; norepinephrine NORMAL cardiovascular dynamics during orthostasis include the displacement of blood from the central circulation into the lower extremities, reduction of venous return, and decreased stroke volume and cardiac output (10). Arterial pressure (AP) is usually not significantly altered during orthostasis in normal individuals due to rapid baroreflex-mediated increases in heart rate (HR) and sympathetic vasoconstrictor nerve activity (5, 22), resulting in increased total peripheral resistance via norepinephrine (NE) secretion (8, 10). These well-synchronized cardiovascular events prevent major abrupt changes in AP and the development of symptoms during orthostatic stress. In autonomic disorders such as the postural tachycardia syndrome (POTS), patients experience exaggerated increases in HR responses (Ն30 beats/min) to head-up tilt (HUT). These patients also present with symptoms of heart palpitations, dizziness, and headaches in the upright posture even when AP appears well maintained although less st...

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confidence: 99%

mentioning

confidence: 99%

Cardiovascular dynamics in healthy subjects with differing heart rate responses to tilt

Ramírez-Marrero¹,

Charkoudian²,

Hart³

et al. 2008

Journal of Applied Physiology

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“…24 A literature review shows increased circulating EPI levels in individuals with OI. 25 Young subjects experiencing orthostatic dysregulation and reductions in mean arterial pressure exhibited a 2-to 8-fold increase in circulating levels of this amine. It is unclear whether altered EPI levels are a cause or the result of OH; however, it has been suggested that EPI contributes to OI by causing peripheral vasodilation and activation of cardiac vagal fibers.…”

Section: Mechanism Of Oh and Oimentioning

confidence: 99%

“…It is unclear whether altered EPI levels are a cause or the result of OH; however, it has been suggested that EPI contributes to OI by causing peripheral vasodilation and activation of cardiac vagal fibers. 25 The mechanism of orthostasis is also disrupted in individuals presenting primary chronic autonomic failure such as pure autonomic failure, multiple system atrophy, and autonomic failure associated with PD. These patients often express reduced sympathetic activity during orthostasis, so their reflexive increases in sympathetic action are not sufficient, and fail to compensate for the decreased venous return to the heart that occurs upon standing.…”

Section: Mechanism Of Oh and Oimentioning

confidence: 99%

A Review of the Etiology, Asssociated Comorbidities, and Treatment of Orthostatic Hypotension

Perlmuter

Sarda²,

Casavant³

et al. 2013

American Journal of Therapeutics

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The magnitude of increase in systolic blood pressure in response to the shift from supine to upright posture is considered to reflect the adequacy of orthostatic regulation. Orthostatic integrity is largely maintained by the interaction between the skeletal muscle pump, neurovascular compensation, neurohumoral effects, and cerebral blood flow regulation. Various physiological states and disease conditions may disrupt these mechanisms as seen in vasovagal syncope, dysautonomic orthostatic intolerance, and postural orthostatic tachycardia syndrome. Orthostatic hypotension (OH) and decreased cerebral blood flow are strongly related. Even subclinical OH has been associated to different degrees with impaired cognitive function, decreased effort, reduced motivation, increased hopelessness, and signs of attention-deficit hyperactivity disorder and dementia, diabetes mellitus, and Parkinson disease. Furthermore, subclinical levels of inadequate blood pressure regulation in response to orthostasis have been linked to increased depression and anxiety and intergenerational behavioral sequelae between mother and child. Identifying causes of subclinical and clinical OH is critical in improving quality of life for both children and older adults. A better understanding of the underlying causes responsible for the etiology of OH could lead to a rational design of novel effective therapeutic regimens for the treatment of this condition and associated comorbidities.

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“…Factors which may influence AP control during orthostasis include sympathetic outflow [6,9,10] and lower-limb anti-gravity muscle activation [3,9,[11][12][13]. However, the interaction of sympathetic outflow and lower-limb anti-gravity muscle activation on orthostatic responses has not been addressed in young and older men.…”

Section: Introductionmentioning

confidence: 99%

Cardiovascular regulation during head-up tilt in healthy 20‒30-year-old and 70‒75-year-old men

GABBETT¹,

WESTON²,

Barrett³

et al. 2001

Clinical Science

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This study compared the heart rate, finger arterial pressure (AP) and electromyographic (EMG) activity of selected anti-gravity muscles during the initial and prolonged phases of orthostatic stress in healthy young and older men. Beat-by-beat recordings of heart rate, finger systolic pressure, diastolic pressure and mean AP were made during supine rest and 5 min of 90 degrees head-up tilt (HUT) in 18 young (23+/-1 years) and 15 older (73+/-1 years) men. The EMG activity of the soleus, tibialis anterior and vastus medialis muscles was recorded. During the first 30 s following 90 degrees HUT (immediate response), the young men exhibited significant (P<0.05) decreases in finger systolic pressure, diastolic pressure and mean AP, followed by a sustained increase in finger AP during the 5 min following 90 degrees HUT (prolonged response). The immediate and prolonged finger AP and diastolic pressure responses were not significantly different (P>0.05) from the values at supine rest for the older men. The mean root mean square EMG activity of the soleus, tibialis anterior and vastus medialis muscles during 90 degrees HUT was not significantly different (P>0.05) from that at supine rest for either group. These results demonstrate that, when compared with healthy older men, young men show larger reductions in finger AP during the initial phase of orthostatic stress. However, during the prolonged phase of orthostatic stress, older men maintain resting finger AP, whereas young men demonstrate a reflex overshoot in finger AP. Finally, differences in lower-limb anti-gravity muscle activation do not account for the contrasting finger AP responses of healthy young and older men.

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Norepinephrine and Epinephrine Responses during Orthostatic Intolerance in Healthy Elderly Men

Cited by 10 publications

References 33 publications

Cardiovascular dynamics in healthy subjects with differing heart rate responses to tilt

Cardiovascular dynamics in healthy subjects with differing heart rate responses to tilt

A Review of the Etiology, Asssociated Comorbidities, and Treatment of Orthostatic Hypotension

Cardiovascular regulation during head-up tilt in healthy 20‒30-year-old and 70‒75-year-old men

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