scholarly journals Neuronal Source of Plasma Dopamine

2008 ◽  
Vol 54 (11) ◽  
pp. 1864-1871 ◽  
Author(s):  
David S Goldstein ◽  
Courtney Holmes
Keyword(s):  
Autonomic Failure ◽  
Sympathetic Nerves ◽  
Plasma Norepinephrine ◽  
Plasma Catecholamine ◽  
Individual Values ◽  
Experimental Conditions ◽  
Endogenous Catecholamine ◽  
Autonomic Testing ◽  
Noradrenergic Nerves ◽  
And Control

Abstract Background: Determinants of plasma norepinephrine (NE) and epinephrine concentrations are well known; those of the third endogenous catecholamine, dopamine (DA), remain poorly understood. We tested in humans whether DA enters the plasma after corelease with NE during exocytosis from sympathetic noradrenergic nerves. Methods: We reviewed plasma catecholamine data from patients referred for autonomic testing and control subjects under the following experimental conditions: during supine rest and in response to orthostasis; intravenous yohimbine (YOH), isoproterenol (ISO), or glucagon (GLU), which augment exocytotic release of NE from sympathetic nerves; intravenous trimethaphan (TRI) or pentolinium (PEN), which decrease exocytotic NE release; or intravenous tyramine (TYR), which releases NE by nonexocytotic means. We included groups of patients with pure autonomic failure (PAF), bilateral thoracic sympathectomies (SNS-x), or multiple system atrophy (MSA), since PAF and SNS-x are associated with noradrenergic denervation and MSA is not. Results: Orthostasis, YOH, ISO, and TYR increased and TRI/PEN decreased plasma DA concentrations. Individual values for changes in plasma DA concentrations correlated positively with changes in NE in response to orthostasis (r = 0.72, P < 0.0001), YOH (r = 0.75, P < 0.0001), ISO (r = 0.71, P < 0.0001), GLU (r = 0.47, P = 0.01), and TYR (r = 0.67, P < 0.0001). PAF and SNS-x patients had low plasma DA concentrations. We estimated that DA constitutes 2%–4% of the catecholamine released by exocytosis from sympathetic nerves and that 50%–90% of plasma DA has a sympathoneural source. Conclusions: Plasma DA is derived substantially from sympathetic noradrenergic nerves.

Does sympathetic dysfunction occur before denervation in pure autonomic failure?

2018 ◽  
Vol 132 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Ling Guo ◽  
Murray D. Esler ◽  
Carolina Sari ◽  
Sarah Phillips ◽  
Elisabeth A. Lambert ◽  
...  
Keyword(s):  
Sympathetic Nerve ◽  
Autonomic Failure ◽  
Muscle Sympathetic Nerve Activity ◽  
Plasma Catecholamines ◽  
Sympathetic Nerves ◽  
Pure Autonomic Failure ◽  
Plasma Norepinephrine ◽  
Multiple Systems ◽  
Sympathetic Dysfunction ◽  
Forearm Vein

Pure autonomic failure (PAF) is a rare sporadic disorder characterized by autonomic failure in the absence of a movement disorder or dementia and is associated with very low plasma norepinephrine (NE) levels—suggesting widespread sympathetic denervation, however due to its rarity the pathology remains poorly elucidated. We sought to correlate clinical and neurochemical findings with sympathetic nerve protein abundances, accessed by way of a forearm vein biopsy, in patients with PAF and in healthy controls and patients with multiple systems atrophy (MSA) in whom sympathetic nerves are considered intact. The abundance of sympathetic nerve proteins, extracted from forearm vein biopsy specimens, in 11 patients with PAF, 8 patients with MSA and 9 age-matched healthy control participants was performed following a clinical evaluation and detailed evaluation of sympathetic nervous system function, which included head-up tilt (HUT) testing with measurement of plasma catecholamines and muscle sympathetic nerve activity (MSNA) in addition to haemodynamic assessment to confirm the clinical phenotype. PAF participants were found to have normal abundance of the NE transporter (NET) protein, together with very low levels of tyrosine hydroxylase (TH) (P<0.0001) and reduced vesicular monoamine transporter 2 (VMAT2) (P<0.05) protein expression compared with control and MSA participants. These findings were associated with a significantly higher ratio of plasma 3,4-dihydroxyphenylglycol (DHPG):NE in PAF participants when compared with controls (P<0.05). The finding of normal NET abundance in PAF suggests intact sympathetic nerves but with reduced NE synthesis. The finding of elevated plasma ratio of DHPG:NE and reduced VMAT2 in PAF indicates a shift towards intraneuronal NE metabolism over sequestration in sympathetic nerves and suggests that sympathetic dysfunction may occur ahead of denervation.

scholarly journals Sympathetic and cardiovascular actions of orexins in conscious rats

1999 ◽  
Vol 277 (6) ◽  
pp. R1780-R1785 ◽  
Author(s):  
Tetsuro Shirasaka ◽  
Masamitsu Nakazato ◽  
Shigeru Matsukura ◽  
Mayumi Takasaki ◽  
Hiroshi Kannan
Keyword(s):  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Sympathetic Nerves ◽  
Plasma Norepinephrine ◽  
High Dose ◽  
Plasma Catecholamine ◽  
Nerve Activity ◽  
Orexin A ◽  
Conscious Rats ◽  
Renal Sympathetic

The novel hypothalamic peptides orexin-A and orexin-B are known to induce feeding behavior when administered intracerebroventricularly, but little is known about other physiological functions. The renal sympathetic nerves play important roles in the homeostasis of body fluids and the circulatory system. We examined the effects of intracerebroventricularly administered orexins on mean arterial pressure (MAP), heart rate (HR), renal sympathetic nerve activity (RSNA), and plasma catecholamine in conscious rats. Orexin-A (0.3, 3.0 nmol) provoked an increase in MAP (94.3 ± 0.7 to 101.9 ± 0.7 mmHg and 93.1 ± 1.1 to 108.3 ± 0.8 mmHg, respectively) and RSNA (28.0 ± 7.0 and 57.9 ± 12.3%, respectively). Similarly, orexin-B (0.3, 3.0 nmol) increased MAP (93.9 ± 0.9 to 97.9 ± 0.9 mmHg and 94.5 ± 1.1 to 105.3 ± 1.7 mmHg, respectively). Orexin-A and -B at 3.0 nmol also increased HR. In other conscious rats, a high dose of orexin-A and -B increased plasma norepinephrine. Plasma epinephrine only increased with a high dose of orexin-A. These results indicate that central orexins regulate sympathetic nerve activity and affect cardiovascular functions.

Role of adrenal medulla in hemodynamic response to hemorrhage and naloxone

1988 ◽  
Vol 254 (3) ◽  
pp. R559-R565 ◽  
Author(s):  
J. C. Schadt ◽  
R. R. Gaddis
Keyword(s):  
Adrenal Medulla ◽  
Pressor Response ◽  
Sympathetic Nerves ◽  
Hemodynamic Response ◽  
Plasma Norepinephrine ◽  
Plasma Catecholamine ◽  
Intact Group ◽  
New Zealand White Rabbits ◽  
Possible Cause

We tested the hypothesis that enkephalins or some other compound(s) released by the adrenal medulla during hemorrhage were responsible for the resultant hypotension. We compared the hemodynamic and plasma catecholamine responses to hemorrhage and subsequent opioid receptor blockade with naloxone in intact, adrenal-denervated (ADD), and adrenalectomized (ADX) rabbits. The studies were done in conscious, chronically prepared, male New Zealand White rabbits. The hemodynamic response to hemorrhage was not different among the three groups. Plasma norepinephrine (NE) increased early in hemorrhage in all groups. In the ADD and ADX animals, NE decreased significantly at the transition to hypotension, suggesting decreased release of NE by peripheral sympathetic nerves as a possible cause of the decrease in pressure. In the intact group, NE did not decrease but reached a plateau possibly due to the release of some NE by the adrenal medulla, which obscured the decreased release by sympathetic nerves. The pressor response to naloxone, though present in all groups, was attenuated by adrenalectomy or adrenal denervation. The plasma NE response to naloxone was similar in all groups and involved a two- to threefold increase after naloxone. We conclude that enkephalins or any other compounds released by the adrenal gland are not responsible for the acute hemodynamic changes during hemorrhage in the conscious rabbit. However, some substance(s) released by the adrenal medulla, perhaps epinephrine, does play a role in naloxone's pressor effect, since this is reduced by adrenalectomy or adrenal denervation.

Vascular reactivity to norepinephrine in rats with cirrhosis of the liver

1988 ◽  
Vol 66 (5) ◽  
pp. 567-572 ◽  
Author(s):  
Luis M. Villamediana ◽  
Godofredo Dieguez ◽  
Juan C. Santos ◽  
Angel L. García-Villalón ◽  
Carlos Caramelo ◽  
...  
Keyword(s):  
Vascular Reactivity ◽  
Contractile Response ◽  
Urinary Metabolites ◽  
Cirrhosis Of The Liver ◽  
Plasma Norepinephrine ◽  
Gas Liquid Chromatography ◽  
Plasma Catecholamine ◽  
Experimental Cirrhosis ◽  
Femoral Arteries ◽  
And Control

Vascular reactivity to norepinephrine was studied in rats with early cirrhosis of the liver and in control rats. Cirrhotic rats showed water and sodium retention but not ascites. Studies were performed in whole animals, isolated hindquarters, and isolated femoral arteries. Plasma catecholamine levels were measured by radioenzymoassay and their urinary metabolites by gas–liquid chromatography. Plasma norepinephrine was 331 ± 49 pg/mL (mean ± SEM) in control rats and 371 ± 66 pg/mL in cirrhotic animals (p > 0.05). No differences in plasma epinephrine or dopamine were observed. Urinary excretion of catecholamine metabolites was increased in cirrhotic rats. These data suggest a moderate activation of the sympathetic nervous system. In basal conditions, cirrhotic rats showed lower mean arterial pressure than controls (101 ± 4 vs. 116 ± 4 mmHg (1 mmHg = 133.3 Pa); p < 0.01). However, perfused hindlimb resistance was similar in cirrhotic and in control animals. In the whole animal and in the perfused hindquarter, the contractile response to norepinephrine was similar for control and for cirrhotic rats. The contractile response to norepinephrine exhibited by isolated femoral arteries was similar in those from cirrhotic and control rats. This indicates that the peripheral vascular bed has a well-maintained ability to constrict in response to norepinephrine, suggesting that circulatory abnormalities in early experimental cirrhosis are not caused by refractoriness of the vascular smooth muscle to norepinephrine.

Desmopressin Stimulates Parallel Norepinephrine and Tissue Plasminogen Activator Release in Normal Subjects and Patients with Diabetes Mellitus

1988 ◽  
Vol 59 (02) ◽  
pp. 269-272 ◽  
Author(s):  
M B Grant ◽  
C Guay ◽  
R Lottenberg
Keyword(s):  
Diabetes Mellitus ◽  
Plasminogen Activator ◽  
Tissue Plasminogen Activator ◽  
Time Course ◽  
Vascular Endothelial Cells ◽  
Normal Subjects ◽  
Plasma Norepinephrine ◽  
Endogenous Catecholamine ◽  
Tissue Plasminogen ◽  
Patients With Diabetes

SummaryDesmopressin acetate administration markedly stimulates release of tissue plasminogen activator (t-PA) from vascular endothelial cells. The mechanism for this effect is unknown. Because infusion of epinephrine has been shown to increase t-PA levels, we examined the role of endogenous catecholamine mediation of t-PA release by desmopressin. Intravenous desmopressin acetate (0.3 μg/kg) was infused over 30 min in 9 controls and 11 subjects with diabetes mellitus, a condition associated with abnormalities of the fibrinolytic system. Plasma was collected in the supine, overnight fasted state at 15 min intervals (0-60 min) for measurement of t-PA activity, t-PA antigen and fractionated catecholamines. t-PA activity peaked at 30-45 min and subsequently decreased. The norepinephrine levels paralleled the t-PA activity. t-PA activity increased 10-fold from 0.14 ± .12 to 1.49 ± 0.79 IU/ml (Mean ± SD) and plasma norepinephrine increased 2- fold from 426 ± 90 to 780 ± 292 pg/ml. However, epinephrine and dopamine levels did not change significantly. The response to desmopressin of control and diabetic subjects was not shown to differ and their data were combined. We conclude that desmopressin increases plasma norepinephrine in addition to t-PA and that the parallel time course of change suggests a possible role for norepinephrine in mediating endothelial cell t-PA release.

scholarly journals Suitability of the Cyclic Voltammetry Measurements and DPPH• Spectrophotometric Assay to Determine the Antioxidant Capacity of Food-Grade Oenological Tannins

Molecules ◽  
2019 ◽  
Vol 24 (16) ◽  
pp. 2925 ◽  
Author(s):  
Arianna Ricci ◽  
Giuseppina Paola Parpinello ◽  
Nemanja Teslić ◽  
Paul Andrew Kilmartin ◽  
Andrea Versari
Keyword(s):  
Cyclic Voltammetry ◽  
Colorimetric Assay ◽  
Radical Scavenging ◽  
Calibration Graph ◽  
Spectrophotometric Assay ◽  
Experimental Conditions ◽  
Fast Analysis ◽  
Cv Measurements ◽  
And Control ◽  
Analytical Approaches

Twenty commercially available oenological tannins (including hydrolysable and condensed) were assessed for their antiradical/reducing activity, comparing two analytical approaches: The 2,2-diphenyl-1-picrylhydrazyl (DPPH•) radical scavenging spectrophotometric assay and the cyclic voltammetry (CV) electrochemical method. Electrochemical measurements were performed over a −200 mV–500 mV scan range, and integrated anodic currents to 500 mV were used to build a calibration graph with (+)-catechin as a reference standard (linear range: From 0.0078 to 1 mM, R2 = 0.9887). The CV results were compared with the DPPH• assay (expressed as % of radical scavenged in time), showing high correlation due to the similarity of the chemical mechanisms underlying both methods involving polyphenolic compounds as reductants. Improved correlation was observed by increasing the incubation time with DPPH• to 24 h (R2 = 0.925), demonstrating that the spectrophotometric method requires a long-term incubation to complete the scavenging reaction when high-molecular weight tannins are involved; this constraint has been overcome by using instant CV measurements. We concluded that the CV represents a valid alternative to the DPPH• colorimetric assay, taking advantage of fast analysis and control on the experimental conditions and, because of these properties, it can assist the quality control along the supply chain.

Catecholamine-fuel interrelationships during exercise in fasting men

1980 ◽  
Vol 48 (1) ◽  
pp. 109-113 ◽  
Author(s):  
J. M. Pequignot ◽  
L. Peyrin ◽  
G. Peres
Keyword(s):  
Maximal Oxygen Consumption ◽  
Plasma Catecholamines ◽  
Plasma Free Fatty Acid ◽  
Work Load ◽  
Bicycle Ergometer ◽  
Plasma Norepinephrine ◽  
Plasma Catecholamine ◽  
Adrenergic Response ◽  
Response To Exercise

Adrenergic response to exercise and the relationships between plasma catecholamines and blood energetic substrates were studied in sedentary men after 15 h of fasting. Subjects pedaled a bicycle ergometer until exhaustion at a work load approximating 80% maximal oxygen consumption. Working ability was diminished by the fast (P less than 0.025). Resting plasma norepinephrine level was increased by fasting. During exercise plasma epinephrine (E) and norepinephrine (NE) concentrations were more elevated in fasting subjects than in fed subjects. Plasma catecholamine (CA) levels in fasting men correlated with blood glucose, blood lactate, and plasma glycerol concentrations. There was no significative correlation between CA and plasma free fatty acid (FFA) levels. The increased adrenergic activity in fasting subjects correlated with reduced endurance time. This study emphasizes the role of CA release, probably combined with other hormonal factors, in the mobilization of energy substrates during submaximal exercise.

scholarly journals The Next Normal for Marketing — The Dynamics of a Pandemic, Provisioning Systems, and the Changing Patterns of Daily Life

2021 ◽  
Vol 29 (1) ◽  
pp. 4-14
Author(s):  
Roger A. Layton ◽  
Christine Domegan
Keyword(s):  
Daily Life ◽  
Social Mechanisms ◽  
Individual Values ◽  
Public And Private ◽  
Supply Networks ◽  
Edge Of Chaos ◽  
Self Organized ◽  
Changing Patterns ◽  
Multi Level ◽  
And Control

Pandemics, climate warming, growing inequality, and much more bring crises that change the patterns of daily life in human communities, directly impacting the provisioning systems that form in a community to meet the needs and wants of individuals, groups, and entities for goods, services, experiences, ideas. Provisioning systems sometimes begin as leadership initiated top-down, authoritarian prescriptive supply networks, public and private. Sometimes, they originate as bottom-up, self-organized, innovative, open choice, often informal, exchange based networks, and mostly, over time, they emerge as untidy self-organized multi-level diverse assemblages of both. The diversity of provisioning systems in a community enables crisis resilience, but limits efficiency and control. The provisioning systems that form in these ways are complex, multi-level, non-linear evolutionary systems, often unpredictable, and lacking direction. Balancing a desire for stability and an appetite for diversity, innovation, and change in shaping a provisioning system is like walking a narrow corridor on the edge of chaos. Achieving balance, avoiding slipping into chaos, rests on the management of a set of complex social mechanisms. These embrace delivery mechanisms where value is produced and consumed through complex infrastructures; stakeholder action fields where trust, collaboration, cooperation, compromise, competition, or conflict are in play; technology evolution mechanisms where innovation and the recombination of existing technologies occur at all levels; and value exchange fields where community and individual values shift in response to crisis and change. Recovery from crisis is not an event, it is a complex, continuing process, often unpredictable, often unequal in outcomes, but walking a narrow corridor is episodic, uncertain and in the end possible. This is the next normal for marketing.

scholarly journals How Downward and Upward Comparisons on Facebook Influence Grandiose and Vulnerable Narcissists’ Self-Esteem—A Priming Study

2021 ◽  
Vol 11 (3) ◽  
pp. 39
Author(s):  
Phillip Ozimek ◽  
Hans-Werner Bierhoff ◽  
Elke Rohmann
Keyword(s):  
Social Networking Sites ◽  
Online Survey ◽  
Social Comparisons ◽  
Past Research ◽  
Self Esteem ◽  
Self Report ◽  
Control Group ◽  
Experimental Conditions ◽  
Vulnerable Narcissism ◽  
And Control

Past research showed that social networking sites represent perfect platforms to satisfy narcissistic needs. The present study aimed to investigate how grandiose (GN) and vulnerable narcissism (VN) as well as social comparisons are associated with Facebook activity, which was measured with a self-report on three activity dimensions: Acting, Impressing, and Watching. In addition, the state self-esteem (SSE) was measured with respect to performance, social behavior, and appearance. One hundred and ten participants completed an online survey containing measures of SSE and Facebook activity and a priming procedure with three experimental conditions embedded in a social media context (upward comparison, downward comparison, and control group). Results indicated, as expected, that high VN was negatively associated with SSE on each subscale and the overall score. In addition, it was found that VN, but not GN, displayed positive associations with frequency of Facebook activities. Finally, it was proposed and confirmed that VN in interaction with the priming of downward comparisons negatively affected SSE. The conclusion drawn is that VN represents a key variable for the prediction of self-esteem as well as for the frequency of Facebook activity.

scholarly journals A gradient field defeats the inherent repulsion between magnetic nanorods

2014 ◽  
Vol 1 (2) ◽  
pp. 140271 ◽  
Author(s):  
Yu Gu ◽  
Ruslan Burtovyy ◽  
John Custer ◽  
Igor Luzinov ◽  
Konstantin G. Kornev
Keyword(s):  
Phase Portrait ◽  
High Speed ◽  
Uniform Magnetic Field ◽  
Gradient Field ◽  
Physical Parameters ◽  
Uniform Field ◽  
Experimental Conditions ◽  
Magnetic Nanorods ◽  
Field Gradients ◽  
And Control

When controlling the assembly of magnetic nanorods and chains of magnetic nanoparticles, it is extremely challenging to bring them together side by side while keeping a desired spacing between their axes. We show that this challenge can be successfully resolved by using a non-uniform magnetic field that defeats an inherent repulsion between nanorods. Nickel nanorods were suspended in a viscous film and a non-uniform field was used to control their placement. The in-plane movement of nanorods was tracked with a high-speed camera and a detailed image analysis was conducted to quantitatively characterize the behaviour of the nanorods. The analysis focused on the behaviour of a pair of neighbour nanorods, and a corresponding dynamic model was formulated and investigated. The complex two-dimensional dynamics of a nanorod pair was analysed analytically and numerically, and a phase portrait was constructed. Using this phase portrait, we classified the nanorod behaviour and revealed the experimental conditions in which nanorods could be placed side by side. Dependence of the distance between a pair of neighbour nanorods on physical parameters was analysed. With the aid of the proposed theory, one can build different lattices and control their spacing by applying different field gradients.

Sign in / Sign up

Export Citation Format

Share Document