Sulfoconjugated Catecholamines Research Articles

Plasma levels of free and sulfoconjugated catecholamines in patients with atherosclerosis.

We have studied the relationship between free and sulfoconjugated catecholamines (CAs) in the plasma of patients with various cardiovascular diseases and have described the physiological significance of sulfoconjugated CAs in plasma. In the present study, we measured free and sulfoconjugated dopamine (DA) and noradrenaline (NA) in the plasma of patients with atherosclerosis (AS). Results showed that the plasma levels of free DA and NA in patients with atherosclerosis were higher than those in control subjects. Moreover, it was also observed that the plasma levels of conjugated DA and NA in patients had a tendency to be higher than the levels in control subjects. These results suggest the involvement of free CAs in atherosclerosis and that elevated free CAs may be converted to sulfoconjugated forms in patients with atherosclerosis.

Influence of Concurrent Heroin and Cocaine Abuse on the Adrenergic and Serotonergic Systems in Mana

Drugs of abuse interfere with the adrenergic activity at the periphery and the study of their effects In Vivo at this level may contribute to understand the central mechanisms of action. Free and sulfoconjugated catecholamines and serotonin (5-hydroxytryptamine, 5-HT) were measured by high-performance liquid chromatography with electrochemical detection (HPLC-ECD); plasma dopamine (DA)-b-hydroxylase (DBH) activity was determined by a HPLC technique. When compared with healthy subjects (n = 49), the results in drug addicts (n = 48) revealed: a) Significant increases in plasma DA (free and sulfoconjugated), epinephrine (Epi)- and norepinephrine (NE)-sulfate levels; b) no significant differences in the levels of plasma free NE or Epi, serum and platelet 5-HT. Concerning DBH activity, there was a tendency for an increase. In conclusion, since catecholamines are rapidly inactivated during blood circulation, the measurement of their sulfates may better reflect catecholamine turnover. The differences found may be interpreted as a reflection of the activation of adrenergic neurotransmission, principally as a consequence of catecholamine uptake blockade by cocaine. Finally, in our conditions the abuse of cocaine plus heroin does not significantly interfere with 5-HT uptake by platelets.

Changes in plasma free and sulfoconjugated catecholamines during the perioperative period of cardiac surgery: effect of continuous infusion of dopamine.

In order to elucidate the pharmacological properties of the formation of sulfoconjugated catecholamines (CAs) in human plasma, we investigated the changes in the plasma levels of free and sulfoconjugated CA during the continuous infusion of dopamine (DA; 4-6 microg/kg/min for 24 h, followed by 3-4 microg/kg/min for 48 h) in patients who had undergone cardiac surgery. The plasma level of free DA increased immediately after the start of the infusion and reached a plateau within 1 h at a level of about 2000 times the basal value. In the control patients who had received non-cardiac surgery without DA infusion, plasma-free DA increased only 5-fold after their operation. The plasma level of DA sulfate increased linearly for 24 h, to 48-fold of the basal value by DA infusion, whereas it showed only a 2-fold increase in the control patients. After 24 h, due to reduction of the infused DA dose, the level of free DA gradually decreased, whereas the level of DA sulfate remained elevated. The plasma levels of free adrenaline (Ad) and noradrenaline (NA) also increased during the DA infusion, but their levels reached a plateau within 1-2 h. Sulfoconjugated Ad and NA increased progressively until the tapering off of DA infusion. In the control patients, both free and conjugated Ad and NA showed transient increases over 12 h after surgery. These results suggest that sulfoconjugation plays a role in regulating the plasma levels of excess free CA, thereby modifying the cardiovascular effects of circulating CA. Measurement of the increase in plasma conjugated CA may be useful as an index of the increase in free CA in plasma due to the administration of an exogenous form or release of endogenous CA from the tissues.

Sulfoconjugated and free plasma catecholamine levels at rest and during exercise in patients with idiopathic dilated cardiomyopathy.

Plasma levels of sulfoconjugated (sc) catecholamines (CA) have been shown to be increased with activation of the sympathoadrenal system in a number of clinical settings. We evaluated the relation between scCA and clinical or hemodynamic parameters of patients with idiopathic dilated cardiomyopathy (IDC) at rest and during incremental exercise testing. Eleven healthy subjects, nine patients in New York Heart Association (NYHA) functional class I (IDC-A group) and 11 in NYHA functional class II and III (IDC-B group) performed a symptom-limited, graded bicycle exercise test. Resting, peak and various postexercise levels of plasma free and scCA were determined by high-pressure liquid chromatography. Resting CA levels obtained in the supine position were remarkable for elevations of free norepinephrine (NE) in IDC-B patients (355 +/- 157 ng/l) as compared to IDC-A patients (177 +/- 54, p = 0.006) or healthy controls (193 +/- 74, p = 0.007). Similarly, scNE was highest in IDC-B patients with 1856 +/- 1089 ng/l, followed by IDC-A (1028 +/- 187, p = 0.025) and control subjects (1109 +/- 440, p = 0.025). There was a highly significant correlation between free and scNE (r = 0.76, p < 0.0005). Whereas resting free dopamine (DA) levels were comparable in all three groups, scDA was found to be elevated clearly in IDC-B patients (8772 +/- 2097 ng/l) and significantly different to IDC-A (5786 +/- 2481, p = 0.01) or control subjects (4892 +/- 1575, p = 0.0005). The NYHA functional class and maximum exercise performance correlated best with resting scDA (r = 0.68, p = 0.001 and r = 0.56, p = 0.005, respectively). At peak exercise, IDC-B patients exhibited a significant decrease in scNE and sc epinephrine (E) (from 1856 +/- 1089 to 1495 +/- 932 ng/l, p < 0.005 and from 491 +/- 173 to 282 +/- 143 ng/l, p < 0.01) compared to controls (from 1109 +/- 444 to 1094 +/- 548 ng/l and from 379 +/- 200 to 329 +/- 134 ng/l). In IDC-B patients this decrease in scNE and scE at peak exercise was related inversely to the rise in free NE and E (r = -0.81, p < 0.005 and r = -0.68, p < 0.05). Resting hemodynamic indices generally were reflected better by some free CA rather than by conjugated forms or by parameters of clinical performance. These findings suggest that in addition to free or scNE levels, resting scDA is elevated in symptomatic patients with IDC.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of corticosteroids on free and sulfoconjugated catecholamines at birth in premature newborn sheep.

We previously demonstrated that prenatal corticosteroids attenuated the expected exponential increase in circulating catecholamines at birth. The present studies were undertaken to determine if alteration in sulfoconjugation could account for this attenuation. Catheterized fetal lambs received saline (n = 6) or corticosteroids (n = 8) intravenously for 60 h. The lambs were delivered by cesarean section at 130 +/- 1 days gestation. Ventilatory and cardiovascular responses and plasma catecholamine concentrations were measured for 2 h after birth. Although plasma free catecholamines levels were higher in controls than in corticosteroid-treated fetuses, the sulfoconjugated levels were similar in the two groups. Thus the corticosteroid-treated fetuses had a higher proportion of plasma sulfoconjugated catecholamines consistent with the possibility that sulfoconjugation was augmented during intrauterine life. After birth, the corticosteroid-treated animals showed an attenuated increase in plasma free catecholamine levels compared with controls but a similar increase in sulfoconjugated catecholamine levels to the control animals. The proportion of plasma sulfoconjugated catecholamines was higher in the corticosteroid-treated animals; however, the increase in sulfoconjugated catecholamines was insufficient to account for the attenuated overall increase in total catecholamines in the corticosteroid-treated animals.

Elevated concentrations of dopamine sulfate in plasma of cocaine abusers

This study investigated the effect of cocaine abuse on peripheral catecholamines. Specifically, we measured the concentration of free dopamine, dopamine sulfate, free norepinephrine, norepinephrine sulfate, free epinephrine and epinephrine sulfate in plasma samples obtained from the blood of a group of patients with cocaine addiction (N = 15). The concentrations of free and sulfoconjugated catecholamines in plasma were measured by a radioenzymatic technique. The results of this study revealed significant (P < 0.0001) elevation in plasma dopamine sulfate (8926 ± 1204 pg/mL) of cocaine addicts upon admission to an in-patient treatment facility when compared with the level of this dopamine metabolite in plasma of control subjects (2356 ± 121 pg/mL). Furthermore, there was a significant (P < 0.0001) relationship between elevation in plasma dopamine sulfate levels and severity of cocaine use among these patients, and in the majority of cases the plasma levels of dopamine sulfate declined appreciably in time with abstinence from cocaine. In contrast, no appreciable difference was observed in the concentrations of either free or sulfate-conjugated norepinephrine and epinephrine in plasma of cocaine addicts as compared with controls. Differences in plasma dopamine sulfate among these patients versus controls may be interpreted as a reflection of activation of extracellular dopamine metabolism associated with chronic cocaine exposure in humans.

Free and conjugated catecholamines and serotonin in canine thoracic duct lymph: effects of feeding

The source and fate of sulfoconjugated catecholamines present in plasma are not known. Sulfated norepinephrine has been shown to overflow together with free norepinephrine from a typical peripheral neuroeffector junction. Some released free norepinephrine is removed via the lymphatic system, but it is not known whether sulfated catecholamines are removed similarly. Serotonin, another biogenic amine, is released from the enterochromaffin cells into portal blood. The aims of the present study were to determine whether conjugated catecholamines and serotonin could be detected in thoracic duct lymph of dogs and to compare concentrations in lymph with those in samples of portal blood collected before and after the dogs were fed. A method is described for the extraction and purification of free and conjugated catecholamines and serotonin from lymph. In lymph and in plasma, there were similar concentrations of free (0.2-0.4 ng/ml) and conjugated (0.1-0.2 ng/ml) norepinephrine and of conjugated dopamine (0.2-1.0 ng/ml). The concentrations of free serotonin were much lower in lymph (0.1-0.2 ng/ml) than in portal blood (100-200 ng/ml). Small amounts of conjugated serotonin (0.1-0.4 ng/ml) were detected in lymph but were not detected in plasma. Feeding caused increases in concentration of conjugated dopamine in lymph and in plasma and small increases in the output of free norepinephrine and free and conjugated serotonin in lymph.

Changes in plasma free and sulfoconjugated catecholamines before and after acute physical exercise in patients with mitral valve prolapse

Changes in plasma free and sulfoconjugated catecholamines before and after acute physical exercise in patients with mitral valve prolapse

Detection and evaluation of persisting stress-induced hormonal disturbances by a post stress provocation test in humans

Eighteen healthy army officers were subjected after prolonged rest to exhaustive ergometric work for about 15 minutes. Before and afterwards blood was taken from the cannulated antecubital vein for determination of free an sulfoconjugated catecholamines, cortisol, glucose, and white blood cell count. One week later, the same procedure was repeated with the same subjects with the difference that the probands underwent about 2.5 hours of difficult mountain climbing and a subsequent rest of 1.5 hours before ergometry. The most important results were: 1) total and bound fractions of catecholamines showed some significant differences between the first and second ergometry due to the previous mountain climbing stress; 2) serum cortisol did not increase after the first ergometry but did so significantly after the second ergometry due to the previous stress; low cortisol is not always indicative of the absence of stress; 3) the absolute number of white blood cells increased in both situttions, correlated significantly with the severity of the stress and the individual increases were more person than situation specific and; 4) blood glucose remained unaffected in both situations. We conclude that a previous stress experience can affect a second stress response and that such a post stress provocation test can uncover persistent hormonal alterations. This procedure may be useful for the evaluation of inaccessible stress situations from subsequent stress measures.

Free and sulfoconjugated catecholamine responses at birth in newborn sheep.

There have been little data on catecholamine sulfoconjugation in developing animals or humans. We studied the differences in free and sulfoconjugated catecholamines at birth in newborn sheep. Baseline concentrations of sulfoconjugated norepinephrine and epinephrine were the predominant form of circulating catecholamine, representing 77 +/- 4 and 65 +/- 12% of total circulating catecholamines, respectively. At birth the free epinephrine concentration increased 10-fold (49 +/- 27 to 653 +/- 21 pg/ml, respectively), and plasma free norepinephrine concentration rose 4-fold (307 +/- 92 to 1,178 +/- 389 pg/ml). In contrast, there was only a transient twofold increase in the sulfoconjugated epinephrine. There was no increase in the sulfoconjugated form of norepinephrine. These data demonstrate that, while the near-term newborn sheep has a well-developed mechanism for sulfoconjugation of circulating catecholamines, this does not occur rapidly. During the logarithmic increases of circulating catecholamines at birth, there are not commensurate increases in the concentration of sulfoconjugated norepinephrine or epinephrine. Thus sulfoconjugation does not appear to represent a significant mechanism for inactivation of the high circulating levels of catecholamines seen at birth.

Changes in plasma free and sulfoconjugated catecholamines before and after acute physical exercise: Experimental and clinical studies

To elucidate whether sulfoconjugated catecholamines in plasma, especially dopamine, serve as a source of free catecholamines, we examined the change in afterload on the deconjugating activity of catecholamines in isolated Langendorff perfused rat hearts. Dopamine-sulfate was administered under ordinary or high-work-load conditions. Free dopamine in the effluent was increased by the high-work-load of the hearts, whereas conjugated dopamine showed an apparent decrease. These results indicate the possibility that deconjugation of sulfoconjugated catecholamines is accelerated by a high-work-load. To obtain further evidence in humans, we also examined the changes in the plasma levels of free and sulfoconjugated catecholamines in healthy volunteers before and after marathon running. Free dopamine increased 1.99-fold from the baseline value after exercise, whereas conjugated dopamine decreased by 12%. Similarly, the plasma levels of free noradrenaline and adrenaline increased after exercise to 2.45- and 1.51-fold their respective baseline values, while conjugated noradrenaline and adrenaline both decreased. These clinical results, as well as those of the experimental studies, suggest that the increase in plasma free catecholamines after exercise is due not only to increased release from the sympathoadrenal system but also to accelerated conversion from sulfoconjugated catecholamines in the plasma.

Changes in plasma free and sulfoconjugated catecholamines before and after acute physical exercise

Changes in plasma free and sulfoconjugated catecholamines before and after acute physical exercise

Sympathetic neuronal activity in diabetic and non-diabetic subjects with peripheral arterial occlusive disease

Despite the vasoconstrictory influence of the alpha-adrenergic system on the peripheral blood circulation the results of the sympathectomy were not satisfying in the therapy of peripheral arterial occlusive disease (PAOD). The aim of the present investigation was to clarify the pathophysiologic mechanisms of this clinical observation. Free and sulfoconjugated catecholamines were determined in the femoral artery, vein, and cubital vein of 19 healthy controls, 21 non-diabetic patients with PAOD stage II, 8 non-diabetic (PAOD IV) and 20 diabetic patients (D IV) with PAOD stage IV. In comparison with controls and group PAOD II an increased sympathoneuronal tone in group PAOD IV was evident at rest. Sympathetic activation was not restricted to the affected limb, since femoral and cubital venous norepinephrine levels were not different and plasma epinephrine fractional extraction (PEFE) was not altered by angiopathy. The lower sympathoneuronal activation in the group D IV may be attributed to an impaired pain perception or a reduced dopamine beta-hydroxylase activity indicated by a lower ratio of norepinephrine to dopamine. The failing long-term efficacy of lumbar sympathectomy in critical arterial limb disease may be explained by marked spontaneous sympathicolysis in diabetics, whereas in non-diabetics with sympathetic activation other mechanisms like development of unilateral Mönckeberg sclerosis, progression of proximal arterial occlusion or induction of steal effects have to be discussed.

Catecholamine sulfates as internal standards in HPLC determinations of sulfoconjugated catecholamines in plasma and urine

A method is described to measure catecholamine sulfates from human plasma and urine by isocratic reversed-phase high-performance liquid chromatography with electrochemical detection. For this measurement we use catecholamine 3-sulfate isomers as internal standards and determine the sulfoconjugates only after eliminating the catecholamines. Catecholamines that have previously been used as internal standards are shown to cause a significant overestimation (P less than 0.05) of the catecholamine sulfates--by 10% to 25% and 20% to 42% in human plasma and urine, respectively. The detection limits (signal-to-noise ratio greater than 3) in plasma and urine samples were about 80 pmol/L for each analyte. The intra-assay and interassay CVs were less than 4.0% and 10.6% in human plasma and less than 6.6% and 12.8% in human urine, respectively. The calibration curves for all catecholamine sulfates in human plasma and urine were linear (r greater than 0.96; P less than 0.001) over the respective concentration ranges of 0.1-100 nmol/L and 5-1000 nmol/L.

Plasma free and sulfoconjugated catecholamines during sustained exercise

Previous research established a relationship between circulating sulfoconjugated norepinephrine (NE-SO4) and oxygen consumption at various exercise intensities. In this study, the stability of the NE-SO4 response was examined during sustained exercise at a constant relative intensity. Seven trained men bicycled at 78 +/- 3% of their maximal O2 consumption for 28 min and then rested on the ergometer for a comparable duration. After a 30-min rest, plasma samples were collected through an indwelling catheter at 7-min intervals during the exercise and recovery periods. Free NE and epinephrine increased sixfold during exercise. These changes were accompanied by increases in sulfoconjugated catecholamines, but only NE-SO4 achieved statistical significance (rest, 712 +/- 602; exercise, 1,329 +/- 1,163 pg/ml). This occurred at three collection periods (14, 21, and 28 min). Approximately 35, 52, and 95% of NE, epinephrine, and dopamine, respectively, existed as sulfoconjugated during exercise. Subject variation was present in the sulfoconjugated catecholamine response that could not be attributed to corresponding differences in circulating free catecholamine release. These findings implicate blood flow as a factor in the sulfoconjugation of NE, but not epinephrine or dopamine.

Free and sulfoconjugated catecholamine responses to hypoxia in fetal sheep

Plasma catecholamines circulate either in conjugated or unconjugated forms. In adult humans, sulfoconjugated catecholamines predominate; however, there is considerable variation between species. In a variety of pathophysiological states catecholamine conjugation is believed to represent an important mechanism of inactivation of high circulating catecholamine levels. To date, there have been few data in developing animals or humans on catecholamine sulfoconjugation. We studied the differences in free and sulfoconjugated catecholamines in full term (141 +/- 1 days) and preterm (123 +/- 1 days) chronically catheterized fetal sheep and determined the changes in free and sulfoconjugated catecholamines in response to hypoxia. The results demonstrate that term and preterm animals have a comparable percentage of basal circulating sulfoconjugated catecholamines (free-to-total ratio 50-60%). In response to hypoxia, both free and sulfoconjugated catecholamines were promptly elevated with significant increases in each by 5 min of hypoxia. This was true for both term and pretern animals. The proportion of free and total catecholamines remained relatively constant during hypoxia despite a 5- to 10-fold increase in circulating levels of each. These data demonstrate that fetal sheep, as early as 80% gestation, have a well developed mechanism for sulfoconjugation and subsequent inactivation of the high circulating levels of catecholamines seen during fetal and newborn life.

Plasma concentrations of free and sulfoconjugated dopamine, epinephrine, and norepinephrine in healthy infants and children.

Plasma concentrations of free and sulfoconjugated catecholamines were measured in healthy infants and children under resting conditions. Free norepinephrine and epinephrine levels were up to three times higher in healthy children under 2 years than in adults, even under true resting conditions. In contrast, free dopamine concentrations of all age groups fell within the normal range for adults. The levels of sulfoconjugation were in the adult range.

Free and sulfoconjugated catecholamines in normotensive uremic patients: effects of hemodialysis.

In 9 normotensive uremic patients undergoing chronic hemodialysis, the baseline plasma catecholamines varied widely from low-normal to very high; sulfoconjugated plasma catecholamines were constantly high. A dialysis-induced fall of all sulfated catecholamines and epinephrine was observed. Norepinephrine decreased in 5 patients and increased in 4, with a strong inverse correlation between predialysis norepinephrine and delta norepinephrine (p less than 0.0001). No correlation was evident between clinical parameters (mean arterial pressure, heart rate) and catecholamines (both predialysis and postdialysis). Significant (p less than 0.0001 and p less than 0.0002) inverse correlations between epinephrine and norepinephrine and their sulfoconjugation degree were demonstrated only in predialysis. Our data may support the presence of a uremic autonomic neuropathy and adrenoceptor damage.

Syntheses of the sulfoconjugated isomers of norepinephrine and dopamine, controlled by HPLC with ultraviolet detection.

The physiological significance of sulfoconjugated catecholamines and their involvement in clinical disorders, e.g. hypertension and Parkinsonism, is poorly investigated. For this reason, the sulfoconjugated isomers of dopamine as well as of norepinephrine were synthesized by modified methods. All isomers and their intermediates could be detected by a reversed-phase high-performance liquid chromatography with ultraviolet detection (HPLC-UV) with short retention times and a good reproducibility. Ion-exchange chromatography with an extended column length improved the separation of the reaction products, and the immediate control by HPLC-UV enabled precise cutting of the fractions. The selection of the fractions with the optimum ratios of product/by-product resulted in improved yields and highest purity. All by-products, e.g. dopamine sulfonic acids, were less than 0.04%, as detected by HPLC-UV and, in addition, the contamination by free catecholamines was only 41 x 10(-4)-87 x 10(-4)%, as measured by HPLC with electrochemical detection (HPLC-ED). The purity was further demonstrated in two highly sensitive biological assays: cAMP production in human mononuclear leukocytes and aggregation of human platelets. The sulfoconjugated catecholamines were characterized by melting point, thin-layer chromatography, infrared spectrum, HPLC-UV, elemental analysis, and unequivocally identified by 1H-NMR.

Determination of free and sulfoconjugated catecholamines in plasma and urine by high-performance liquid chromatography.

The determination of free and sulfoconjugated catecholamines (CA) in serum and urine with amperometric detection after HPLC separation is described. The reliability of this method has been extensively investigated. Since in men 69-90% of the total CA are sulfoconjugated, an enzymatic hydrolysis of these conjugates with arylsulfatase VI has been elaborated and optimized for a routine assay. The reproducibility with coefficients of variation between 1% and 3% for free and 5% and 10% for conjugated CA and recovery rates of 65%-75% for both were found. The calibration plots were linear between 10 and 5000 ng/l and the smallest detectable amount of CA was 0.1 nmol/l. The sample amount of 0.75 to 1.0 ml for free and 0.2 ml for conjugated CA was lower than with the extraction method (18) which needs 3 ml of serum. Using an automatic sampler, the sampling rate was 50-60 p.d. With the Al2O3 adsorption and the same buffer eluent system, L-dopa can also be detected at the same voltage of 700 mV. The values obtained for the HPLCA described method correlated well with those of the radio enzyme assays according to Da Prada et al. The HPLCA detection of free and sulfoconjugated CA in urine was carried out after an ion exchange column procedure on Biorex 70. The validity of the urine assay was at least as reliable as the determination of free and conjugated CA in plasma.