Catecholamines In Man Research Articles

Evidence for inhibition of leptin secretion by catecholamines in man.

The regulation of leptin secretion is complex and not entirely understood in humans. Insulin has been shown to stimulate leptin secretion in humans, whereas in vitro data suggest that catecholamines inhibit leptin secretion. The present studies were therefore undertaken to examine the leptin response to hyperinsulinemia in the presence and absence of elevated plasma levels of endogenous catecholamines in humans. Leptin concentrations were determined during both a euglycemic and hypoglycemic hyperinsulinemic clamp study in 10 normal and 10 type I diabetic subjects. Serum leptin increased during the hyperinsulinemic euglycemic clamp in normal (from 6.1 +/- 0.9 to 7.2 +/- 1.1 ng/dl, p = 0.003) and diabetic subjects (from 6.2 +/- 1.4 to 7.8 +/- 1.8 ng/dl, p = 0.001). During hyperinsulinemic hypoglycemia leptin concentrations increased significantly in type 1 diabetic patients (from 5.6 +/- 1.1 to 7.6 +/- 1.7 ng/dl, p = 0.003) but remained unaltered in normals (from 5.5 +/- 0.7 to 5.7 +/- 0.9 ng/dl, p = 0.7). During hypoglycemia in all subjects the increase in leptin was negatively correlated with the increase in epinephrine (r = 0.60, p = 0.005) and positively with the decrease in free fatty acids (r = 0.71, p = 0.003). In conclusion our results indicate that catecholamines play a suppressive role in the regulation of leptin secretion.

Stress and catecholamines.

Stress and catecholamines.

Different expression of catecholamine transporters in phaeochromocytomas from patients with von Hippel-Lindau syndrome and multiple endocrine neoplasia type 2

Phaeochromocytomas in patients with multiple endocrine neoplasia type 2 (MEN 2) produce adrenaline, whereas those with von Hippel-Lindau (VHL) syndrome do not. This study assessed whether these distinctions relate to differences in expression of the transporters responsible for uptake and storage of catecholamines - the noradrenaline transporter and the vesicular monoamine transporters (VMAT 1 and VMAT 2). Tumour tissue and plasma samples were obtained from 31 patients with hereditary phaeochromocytoma - 18 with VHL syndrome and 13 with MEN 2. We used quantitative PCR, Western blotting, electron microscopy, immunohistochemistry and measurements of plasma and tumour catecholamines to assess differences in expression of the transporters in noradrenaline-producing vs adrenaline-producing hereditary tumours. These differences were compared with those in a further group of 26 patients with non-syndromic phaeochromocytoma. Adrenaline-producing phaeochromocytomas in MEN 2 patients expressed more noradrenaline transporter mRNA and protein than noradrenaline-producing tumours in VHL patients. In contrast, there was greater expression of VMAT 1 in VHL than MEN 2 tumours, while expression of VMAT 2 did not differ significantly. These differences were associated with larger numbers of storage vesicles and higher tissue contents of catecholamines in MEN 2 than in VHL tumours. Differences in expression of the noradrenaline transporter were weaker, and those of VMAT 1 and VMAT 2 stronger, in noradrenaline and adrenaline-producing non-syndromic than in hereditary tumours. The findings show that, in addition to differences in catecholamine biosynthesis, phaeochromocytomas in MEN 2 and VHL syndrome also differ in expression of the transporters responsible for uptake and vesicular storage of catecholamines.

Effects of melatonin on vascular reactivity, catecholamine levels, and blood pressure in healthy men

In this study it was investigated whether the oral administration of melatonin (1 mg) in comparison to placebo was able to reduce blood pressure, vascular reactivity, and catecholamines in men, as previously reported in young women. The administration of melatonin significantly reduced blood pressure, the pulsatility index in the internal carotid artery, and catecholamines levels within 90 minutes. The effect of melatonin on the artery pulsatility index was related to baseline values, being greater in men with higher baseline values. The present data indicate that melatonin may blunt the activity of the cardiovascular system and may have both physiopathologic and clinical implications.

Metabolic actions of catecholamines in man

Metabolic actions of catecholamines in man

Intraindividual variation of beta 2-adrenergic receptors on mononuclear leukocytes and their relationships with endogenous plasma catecholamines in man.

The interindividual and intraindividual variations of both MNL beta 2-adrenergic receptor density and dissociation constant of binding were evaluated in 19 healthy volunteers. In addition the possible relationships between catecholamine plasma levels and MNL beta 2-adrenergic receptor density were studied in 8 of these subjects. The volunteers were studied three times with ten days' interval. There was a significant inverse relationship between receptor density and norepinephrine plasma levels, only. Neither epinephrine nor dopamine were correlated with receptor density. Interindividual coefficient of variation was 29.57%. The mean value of the intraindividual coefficients of variation was 14.1%, while the mean value of the analytical coefficients of variation was 10%. Our results are at some variance with data in the literature and may contribute to elucidate the role of MNL beta 2-adrenergic receptors as an index of sympathetic function in man.

Clonidine and Alcohol Withdrawl

Clonidine attenuates opiate withdrawal syndrome, via reduction in catecholamine activity in the brain, most probably at the locus ceruleus. Clonidine and locus ceruleus lesions, in animals with alcohol dependency as with the opiates, modify alcohol withdrawal. Both alcohol loading and withdrawal from steady alcohol use alter catecholamines in man and animals. Clonidine's potential to treat alcoholics in withdrawal is reviewed. Several double blind studies showed clonidine, or similar analogues, to be somewhat superior to placebo in acute alcohol withdrawal. Major improvements were in pulse, blood pressure and composite alcohol withdrawal scores. Side effects were minor and mainly included mild sedation, or postural hypotension. In the only available published study clonidine compared reasonably well to a standard sedative in alcohol withdrawal, and greatly influential in plasma catecholamine levels. Other components of alcohol withdrawal, as seizures and hallucinations-delirium tremens have not been documented to change with clonidine. The alpha-2-adrenergic agonists in alcohol treatment seemed modestly effective for treatment of some parts of alcohol withdrawal. They represent a promising, novel, but still investigational approach. Additional data, particularly comparing them to the benzodiazepines, are needed before their potential in therapeutics can be assessed.

Circadian fluctuation of plasma epinephrine in supine humans

Previous studies have demonstrated circadian fluctuations of systemic catecholamines in man. However, methodological differences and conflicting results with epinephrine are apparent. In the present study, plasma and urinary epinephrine and norepinephrine and plasma cortisol were studied in healthy young adult males over 24 hr with 20 min plasma sampling and EEG monitoring of sleep. Plasma epinephrine did not have a circadian variation in supine subjects. Urinary epinephrine levels and small urinary circadian variations were increased by normal posture and activity. Sleep and sleep stage were not associated with different plasma epinephrine levels, and no ultradian fluctuation was observed. Levels of norepinephrine and cortisol were normal. Based on all studies to date, it appears that basal plasma epinephrine has either a very small amplitude or no circadian rhythm, but that changes in posture and activity or the rest/activity cycle may modify this pattern.

Effects of lithium administration on plasma catecholamines

The mode of action of lithium in the treatment of bipolar affective disorder is unknown. Among its actions are effects on release and response to catecholamines in experimental animals. We have therefore examined its effect on peripheral catecholamines in man. After 3 weeks of administration of therapeutic doses of lithium carbonate, healthy volunteers showed a differential response of catecholamines to insulin stimulation. Although the response of plasma norepinephrine remained unchanged, epinephrine response was dramatically reduced. These findings provide additional evidence for the separate neural regulatiof the adrenal medulla and sympathetic nerve endings. Further studies are necessary to determine whether these effects on peripheral epinephrine are paralleled by changes in central epinephrine.

Calendar of continuing medical education

Clinical CardiologyVolume 9, Issue 5 p. A30-A30 CalendarFree Access Calendar of continuing medical education First published: May 1986 https://doi.org/10.1002/clc.4960090519AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. References Bazett HC: An analysis of the time relations of electrocardiograms. Heart 7, 353 (1920) Boudoulas H, Reynolds JC, Mazzaferri E, Wooley CF: Metabolic studies in Mitral valve prolapse syndrome. A neuroendocrine-cardiovascular process. 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Br J Clin Pharmacol 3, 963 (1976) Pasternac A, Tubau JF, Puddu PE, Król RB, de Champlain J: Increased plasma catecholamine levels in patients with symptomatic mitral valve prolapse. Am J Med 73, 783 (1982) Puddu PE, Pasternac A, Tubau JF, Król R, Farley L, de Champlain J: QT interval prolongation and increased plasma catecholamine levels in patients with mitral valve prolapse. Am Heart J 105, 422 (1983) Robertson D, Johnson GA, Robertson RM, Nies AS, Shand DG, Oates JA: Comparative assessment of stimuli that release neuronal and adrenomedullary catecholamines in man. Circulation 59, 637 (1979) Savage DD, Devereux RB, Garrison RJ, Castelli WP, Anderson SJ, Levy D, Thomas HE, Kannel WB, Feinleib M: Mitral valve prolapse in the general population. 2. Clinical features: The Framingham Study. Am Heart J 106, 577 (1983a) Savage DD, Levy D, Garrison RJ, Castelli WP, Kligfield P, Devereaux RB, Anderson SJ, Kannel WB, Feinleib M: Mitral valve prolapse in the general population. 3. 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24 h excretion patterns of free, conjugated and methylated catecholamines in man.

A method based on high performance liquid chromatography with electrochemical detection is described for quantification of adrenaline, noradrenaline, dopamine (free and total), metanephrine, normetanephrine, and 3-methoxytyramine (free) in urine samples. Purification of the samples is achieved on disposable Bio-Rad ion-exchange columns in combination with small Sephadex G 10 columns. A clear circadian rhythm was found in the 24 h excretion pattern of free adrenaline and noradrenaline for 4 volunteers (city bus drivers during a working day). No rhythms were seen in the 24 h excretion pattern of free or conjugated dopamine, conjugated adrenaline or conjugated noradrenaline, or of the methylated free catecholamines. It is concluded that in order to obtain information about the neurotransmitter function of peripheral catecholamines it is sufficient to determine the non-conjugated compounds; values for the conjugated and methylated metabolites contribute no extra information.

Effects of a prostacyclin analog iloprost on kidney function, renin-angiotensin and kallikrein-kinin systems, prostanoids and catecholamines in man

Iloprost (ZK 36 374), a stable analog of carbaprostacyclin, was infused for 72 h to nine patients with advanced obliterative arterial disease. Iloprost caused a marked vasodilation and a compensatory increase in cardiac output. The glomerular filtration rate increased by 45% and tubular reabsorption of sodium and water were reduced by 80% and 107%, respectively. The urine excretion rate increased by 122%. Tubular handling of potassium and calcium were not influenced by iloprost but magnesium reabsorption was stimulated. The renin-angiotensin system was not activated while serum angiotensin converting enzyme activity was decreased. Kallikrein excretion in urine was increased 4.4-fold but plasma kininogen, a substrate for kallikrein in producing vasoactive kinins, was unaffected by the drug. Plasma levels of 6-keto-PGF 1 α and TxB 2 were decreased and their excretion in urine increased. Plasma catecholamines were not changed by iloprost. Several of the changes persisted for at least the first postinfusion day. The results indicate that iloprost increases urine excretion rate by increasing glomerular blood flow and by inhibiting sodium and water reabsorptions. The kinin-forming system, but not the renin-angiotensin system or plasma catecholamines, may be activated. The decrease in plasma level of prostanoids can be, at least partly, due to their increased excretions in urine.

Histofluorescent and radioenzymatic analysis of colonic catecholamines in man

Colonic tissues from patients with ulcerative colitis (UC), ileal tissue from patients with Crohn's disease (CD), and other ileocolonic disorders were radioenzymatically assayed for norepinephrine (NE) and dopamine (DA). These assays showed that the NE content of UC colon ranged from 3.2 to 4.3 ng/mg wet tissue, while in other colonic disorders it ranged from 3.0 to 5.3 ng/mg. Similarly, the DA content of UC colon ranged from 0.42 to 1.17 ng/mg wet tissue, while for other colonic disorders it ranged from 0.48 to 0.89 ng/mg. The same tissues were examined histochemically using glyoxylic acid condensation of catecholamines (CA) for the semi-quantitation of CA-containing structures. Examination of these structures revealed an apparent increase in their staining intensity in the myenteric plexus in ulcerative colitis as compared to other colonic disorders. Morphologically, the CA-containing structures of the colon appeared to be increased in UC, but determination of the NE and DA concentrations in colonic samples revealed no statistically significant differences in comparable regions of the colon.

Dihydrocaffeic acid: a common contaminant in the liquid chromatographic-electrochemical measurement of plasma catecholamines in man

Dihydrocaffeic acid: a common contaminant in the liquid chromatographic-electrochemical measurement of plasma catecholamines in man

The influence of oral tyrosine and tryptophan feeding on plasma catecholamines in man

We investigated the effects of oral tyrosine (7.5 g/day) and oral tryptophan (3 g/day) feeding with regular meals in normal male volunteers using a double-blind cross-over design with a “run in” period for acclimatization. Oral tyrosine feeding significantly decreased both free and conjugated plasma norepinephrine concentrations while oral tryptophan feeding did not have such an effect. Since α adrenergic stimulation in certain areas of the CNS has been shown to decrease peripheral sympathetic tone, we postulate that dietary tyrosine supplementation in man causes an increase in brain catecholaminergic activity which in turn leads to a decrease in peripheral sympathetic activity as evidenced by the decrease in plasma catecholamines.

The Influence of Arterial Baroreceptors in Man on the Variability of Blood Pressure and Plasma Catecholamines in Man

The variability of intra-arterial blood pressure, recorded over the waking hours in free-ranging subjects away from the hospital, was expressed as the SD of the mean of all recorded beats. This variability was found to be related to age, the individual's level of arterial pressure, and his baroreflex sensitivity using the Oxford phenylephrine method. Multiple regression analysis showed that baroreflex sensitivity was the only independent influence on variability. Baroreflex sensitivity also strongly determined the level of pressure rise in response to a number of different stimuli, including bicycling exercise, isometric exercise, mental arithmetic, a reaction time test, and the response to injected phenylephrine or noradrenaline. Plasma noradrenaline proved a poor index of sympathetic nervous activity, except with bicycle exercise.

The Influence of Arterial Baroreceptors in Man on the Variability of Blood Pressure and Plasma Catecholamines in Man

There are several methods of expressing the variability of arterial pressure, but the most generally accepted method is to use the SD about the mean. Even within this definition there is room for differing interpretations. We define variability as the SD of all the individual pulses obtained during the period of recording.

Cold-induced Changes in Plasma Catecholamines in Men

Cold-induced Changes in Plasma Catecholamines in Men

Relationship between Sleep Efficiency Index and Urinary Catecholamines in Man

Relationship between Sleep Efficiency Index and Urinary Catecholamines in Man

Arterial-venous differences of plasma catecholamines in man

To investigate the relationship between forearm venous levels of catecholamines and systemic levels, simultaneous arterial and forearm vein blood samples were obtained from 14 subjects undergoing elective dental procedures and assayed with a sensitive and specific radioenzymatic assay. Baseline venous levels of norepinephrine were greater than arterial levels (305 ± 30 pg/ml versus 221 ± 18; ± SEM, p < .005). Conversely, arterial epinephrine levels were higher than venous (132 ± 17 pg/ml versus 80 ± 10; p < .005). There was a significant relationship between arterial and venous levels of both norepinephrine ( r = .77, p < .01) and epinephrine ( r = .67, p < .01). The arterial-venous epinephrine difference increased from the baseline value of 44 ± 14 pg/ml to 108 ± 16 ( p < .005) by 3 min after subcutaneous injection of epinephrine (18 μg), but the arterial-venous difference returned to 65 ± 24 by 5 min after injection ( p = NS versus baseline). These findings indicate that under the conditions of this study, forearm tissues produced more norepinephrine than they removed, but removed more epinephrine than they produced. Baseline venous and arterial levels were related; when epinephrine production was augmented, there was a short time lag for the venous epinephrine increase.