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PubMed1981

Catecholamine fluorescence and tissue culture morphology. Technics in the diagnosis of neuroblastoma.

Neuroblastoma is often confused histologically with other small round cell tumors such as Ewing's sarcoma, acute lymphocytic leukemia, lymphoma, and oat cell carcinoma, particularly at metastatic sites. Studies were performed to evaluate glyoxylic acid-induced catecholamine fluorescence as a rapid method for identifying neuroblastoma cells in biopsy specimens. The morphology of tumor explants in tissue culture was also evaluated for use as a diagnostic aid. Eighteen neuroblastomas were stained for catecholamines; 78% showed specific catecholamine fluorescence. Two ganglioneurons and a pheochromocytoma also showed positive catecholamine fluorescence. All 20 neuroblastomas placed in tissue culture demonstrated neurite outgrowth, a property that distinguishes neuroblastoma from other small round cell neoplasms. Seventeen nonneuroblastoma tumors displayed neither specific fluorescence nor neurite outgrowth. The ability of these two technics to identify neuroblastoma was compared with routine histology, urinary vanillylmandelic acid (VMA) spot tests, quantitative urinary VMA and catecholamine assays, and electron microscopy. Only electron microscopy was as sensitive as fluorescence and morphology in culture. The fluorescence method is rapid and simple and provides a valuable tumor marker when positive. Neurite outgrowth in cell culture and electron microscopy, although more time-consuming, were the most sensitive of all the diagnostic methods evaluated.

Adult↗
PubMed1982

Use of metyrosine in the anaesthetic management of patients with catecholamine-secreting tumours. A case report.

Metyrosine 1.5 g daily for days decreased 24-h urine metanephrine concentration by about 60% in a patient with multiple catecholamine-secreting paragangliomas. Despite the considerable inhibition of catecholamine synthesis, this patient exhibited stress-induced sympathetic overactivity, indicated by increases in arterial pressure and serum catecholamine and urine metanephrine concentrations. It is concluded that metyrosine should be introduced early to the preoperative regimen. In this way, optimal inhibitory effect on catecholamine synthesis can be obtained and maintained for a sufficient time to allow catecholamine stores to become as close to normal as possible. Attainment of the optimal therapeutic effect is not clearly defined, but would seem to be best gauged by a combination of clinical tests of sympathetic responses and of suppression of urinary excretion of metanephrines or VMA.

Anesthesia, Epidural↗
PubMed1995

Haemodynamic and catecholamine responses to induction of anaesthesia and tracheal intubation in diabetic and non-diabetic uraemic patients.

We have studied cardiovascular and catecholamine responses to induction of anaesthesia and tracheal intubation in 13 patients with diabetic nephropathy, in 12 patients with uraemia of other origin and in 12 ASA I control patients. All uraemic patients were undergoing renal transplantation. Cardiovascular autonomic function tests indicated that severe autonomic neuropathy was common in the diabetic patients; less severe impairment of autonomic function was found in the non-diabetic uraemic patients. The systolic pressor response to intubation was greater in diabetic uraemic patients than in the other groups (P < 0.05). Both uraemic groups had higher plasma catecholamine concentrations than the ASA I patients both before and after induction of anaesthesia. The increased plasma concentrations of catecholamines in the uraemic patients may be a result of impaired clearance of catecholamines and higher sympathoadrenal activity needed to maintain cardiac function. The normal systolic pressor response to tracheal intubation in the uraemic patients indicates that the capacity of the cardiovascular system to respond to a stressful stimulus was preserved in these patients also, in spite of autonomic neuropathy. The greater response in the diabetic group may be caused by increased sensitivity to catecholamines and loss of autonomic control.

Adult↗
PubMed1983

The role of adrenal medullary catecholamine release in the response to a cold pressor test.

We studied the effects of a cold pressor test on the plasma catecholamine levels of ten patients undergoing coronary angiography, to determine whether the pressor changes were related to adrenergic activity. To investigate the relative contribution of adrenal medullary catecholamine release, we subjected two adrenalectomised volunteers to the same test. Arterial blood was assayed for dopamine (DA), adrenaline (A) and noradrenaline (NA). We found significant rises in the levels of all three catecholamines in the angiography patients, accompanied by a significant elevation in arterial blood pressure. In both the adrenalectomised patients a rise in blood pressure was seen but no significant rise in plasma catecholamines could be demonstrated. We postulate that although adrenal medullary catecholamine release occurs in response to the cold pressor test, the blood pressure elevation is independent of such adrenal activity. Sampling radial arterial blood may not reflect changes in plasma levels of peripherally released NA.

Adrenal Medulla↗
PubMed2001

The effect of noise on serum and urinary magnesium and catecholamines in humans.

We have studied whether a short-term exposure to loud noise was able to modify urinary catecholamine excretion and serum concentration and urinary excretion of magnesium and other related electrolytes. In 25 healthy volunteers, blood and urine concentrations of magnesium, calcium, phosphorus and creatinine, and urinary catecholamines were measured before and after exposure to noise in an industrial plant. Samples were collected at 08:00 h on the day of the experiment and soon after noise exposure (at 20:00 h). Two further urine samples were collected the following day and 2 days after the experiment, always at 08:00 h in the morning. The sound energy average level was 98 dB(A), but peak levels reached 108 dB(A). Urinary catecholamines were determined by high-performance liquid chromatography. Serum magnesium and calcium were significantly increased after exposure to noise, whereas phosphorus displayed a similar but non-significant trend (P = 0.065). Multivariate analysis of variance (ANOVA) showed significant differences both among subjects (P < 0.001) and after exposure (P < 0.001). Adrenaline, noradrenaline and dopamine values were not significantly different after exposure to noise (P > 0.05). Urinary magnesium levels were significantly different across time (P = 0.017). Urinary calcium levels were not significantly different across time (P = 0.36). Urinary phosphate values were increased after exposure to noise (P = 0.007); urinary creatinine was not changed after exposure (P > 0.05). Our study shows that noise induces significant increases of serum calcium and magnesium, with a borderline increase of serum phosphorus; this in turn is reflected in a significantly increased urinary excretion of magnesium and phosphate after exposure, which lasts for the following 2 days. Urinary calcium and creatinine were not modified by noise. The difference in catecholamine values did not reach statistical significance. Thus, we failed to substantiate a significant correlation between catecholamine secretion and magnesium metabolism, as others had suggested.

Adult↗
PubMed1984

The deleterious effects of myocardial catecholamines on cellular electrophysiology and arrhythmias during ischaemia and reperfusion.

Action potentials and ECGs were recorded from Langendorff perfused guinea pig hearts during ischaemia and reperfusion. Arrhythmias were significantly more frequent during low flow (10% of control) than zero flow ischaemia and were most frequent during reperfusion following 30 minute ischaemia. Arrhythmias during low flow ischaemia were preceded by spontaneous recovery in action potential amplitude and Vmax and marked shortening of refractory period which did not occur during zero flow ischaemia. Reperfusion VF was always preceded by further shortening of the action potential. Myocardial catecholamine depletion, by pre-treatment with 6-hydroxydopamine significantly reduced the incidence of arrhythmias during ischaemia and reperfusion. Catecholamine depletion blunted the ischaemia-induced reduction in action potential amplitude and Vmax, prevented any spontaneous recovery and abolished reperfusion induced shortening of action potential duration. Methoxamine given to catecholamine-depleted hearts, having only minor effects during normal perfusion, significantly reversed the anti-arrhythmic and electrophysiological effects of catecholamine depletion during ischaemia and reperfusion. Phentolamine and propranolol in anti-arrhythmic concentrations, profoundly modified the electrophysiological effects of ischaemia and reperfusion. These results suggest that release of endogenous myocardial catecholamines contributes through alpha and beta-adrenoceptor stimulation to the electrophysiological changes and arrhythmias during myocardial ischaemia and reperfusion.

Action Potentials↗
PubMed1986

Catecholamine content of the preovulatory follicles of the domestic hen.

The role of catecholamines in ovarian function of the domestic hen has not been examined extensively. The aim of this study was first to determine the location of catecholamines in the preovulatory follicle of the domestic hen. Second, norepinephrine (NE), epinephrine (EPI) and dopamine (DA) were measured in the isolated theca layer of the five largest preovulatory follicles at specific times during the ovulatory cycle and changes in catecholamine content were correlated with ovarian events. The five largest preovulatory follicles were removed from chickens at 24, 18, 12, 6 and 2 h before ovulation of the largest (F1) follicle. Theca and granulosa layers were isolated, frozen, weighed and prepared for measurements of catecholamines by the double isotope radio-enzymatic assay. Catecholamines were localized primarily in the theca layer with only small amounts present in the granulosa layer. Norepinephrine was present in the theca layer in concentrations 6- and 30-fold those of EPI and DA, respectively. The content of NE and EPI in the theca layer of the F1 follicle was significantly (p less than 0.01) higher at 6 h before ovulation than at other times for the F1 follicle. In contrast, NE and EPI content of the theca layer of second (F2) and third (F3) largest follicles did not change during the ovulatory cycle. The content of DA was elevated (p less than 0.05) at 12 h before ovulation in F1 and F2 follicles. There was a significant reduction in NE in the theca layer of the fifth largest (F5) follicle between 24 and 18 h before ovulation of the F1 follicle.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Maternal plasma catecholamines in the rhesus macaque during late gestation: effect of photoperiod and timed melatonin infusion.

This study tested the hypothesis that changes in photoperiod alter plasma catecholamine concentrations in the rhesus monkey during late gestation. Twelve chronically catheterized pregnant rhesus macaques were acclimated to a 12-h photoperiod (lights-on, 0700-1900 h). Under the control L:D cycle, blood samples were collected at 3-h intervals over 24 h for catecholamine analysis. Plasma concentrations (mean +/- SEM, pg/ml) ranged from 678 +/- 90 to 928 +/- 142 for norepinephrine; 230 +/- 22 to 631 +/- 141 for epinephrine; and 282 +/- 70 to 1090 +/- 362 for dopamine. A diurnal rhythm was observed in epinephrine with peak concentrations during lights-on (0900-1800 h; p less than 0.05, compared to lights-off). After the first sampling protocol, the animals were divided equally between two groups: phase shift, in which lights-on was shifted 11 h (2000-0800 h) and constant light, with lights on continuously. After the phase shift, a parallel shift in the plasma epinephrine rhythm was noted, with peak levels observed between 2200 and 0700 h (p less than 0.05). Constant light abolished the rhythm in epinephrine, with an overall reduction in mean basal levels of all three catecholamines. Daily melatonin infusions (0.2 micrograms/kg/h, 1900-0630 h) under constant light failed to restore the epinephrine rhythm or to return basal catecholamine concentrations to control photoperiod levels. These data suggest that photoperiod entrains the rhythm in epinephrine secretion, but the rhythm is ablated under constant conditions. Further, melatonin does not appear to play a role in the regulation of catecholamine secretion in the pregnant rhesus macaque.

Animals↗
PubMed1996

Clonidine modulation of hemodynamic and catecholamine responses associated with hypoxia or hypercapnia in dogs.

BACKGROUND: Hypoxia or hypercapnia elicits cardiovascular responses associated with increased plasma catecholamine concentrations, whereas clonidine, an alpha(2)- adrenergic agonist, decreases plasma catecholamine concentrations. The authors examined whether systemic clonidine administration would alter the hemodynamic and catecholamine responses to hypoxia or hypercapnia in anesthetized dogs. METHODS: Pentobarbital-anesthetized dogs whose lungs were mechanically ventilated were instrumented for measurement of mean arterial pressure, heart rate, mean pulmonary artery pressure, right atrial pressure, cardiac output, left ventricular end-diastolic pressure, and the peak of first derivative of left ventricular pressure. The dogs were randomly assigned to receive an intravenous bolus injection of 10 microg/kg clonidine followed by continous infusion at a rate of 1 microg. kg (-1). min (-1)(clonidine-10 group, n = 7), an intravenous bolus injection of microg/kg clonidine followed by continuous infusion at a rate of 0.5 micro.kg(-).min(-1)(clonidine-5 group, n = 7), or an equivalent volume of 0.9% saline (control group = 7). Each dog underwent random challenges of hypoxia (PaO2 30, 40, and 50 mmHg) and hypercapnia (PaCO2 60, 80, and 120 mmHg). Measurements of hemodynamic and plasma norepinephrine and epinephrine concentrations were made after the loading dose of clonidine and the first and the second exposure of hypoxia or hypercapnia. RESULTS: Although significant increases from prehypoxic values in mean arterial pressure (39 +/- 10 mmHg) and plasma norepinephrine (291 +/- 66 pg/ml) and epinephrine (45 +/- 22 pg/ml) concentrations were noted during hypoxia of PaO2 30, mmHg in the control group (P<0.05), such changes were absent in both clonidine groups. During hypercapnia of PaCo2 120 mmHg, changes from prehypercapnic values in mean arterial pressure, mean pulmonary artery pressure, the peak of first derivative of left ventricular pressure, and plasma norepinephrine and epinephrine concentrations in the clonidine-10 and clonidine-5 groups were significantly less than those in the control group. Plasma clonidine concentrations in the clonidine-10 and clonidine-5 groups were 16.8 +/- 1.7 and 8.9 =/- 1.0, 42.5 =/- 2.9 and 21.5 +/- 1.5, and 51.1 +/- 3.2 and 26.7 +/- 1.0 ng/ml after the loading dose of clonidine and the first and the second exposure of hypoxia or hypercapnia, respectively. CONCLUSIONS: Systemic clonidine administration alter the hemodynamic changes associated with hypoxia or hypercapnia and suppresses plasma catecholamine responses in anesthetized dogs when a larger dose of clonidine is administered. catecholamines: epinephrine; norepinephrine.)

Adrenergic alpha-Agonists↗
PubMed1997

Urine and plasma catecholamine and cortisol concentrations after myocardial revascularization. Modulation by continuous sedation. Multicenter Study of Perioperative Ischemia (McSPI) Research Group, and the Ischemia Research and Education Foundation (IREF).

BACKGROUND: Cardiopulmonary bypass is associated with substantial release of catecholamines and cortisol for 12 or more h. A technique was assessed that may mitigate the responses with continuous 12-h postoperative sedation using propofol. METHODS: One hundred twenty-one patients having primary elective cardiopulmonary bypass graft (CABG) surgery were enrolled in a double-blind, randomized trial and anesthetized using a standardized sufentanil-midazolam regimen. When arriving at the intensive care unit (ICU), patients were randomly assigned to either group SC (standard care), in which intermittent bolus administration of midazolam and morphine were given as required to keep patients comfortable; or group CP (continuous propofol), in which 12 h of continuous postoperative infusion of propofol was titrated to keep patients deeply sedated. Serial perioperative measurements of plasma and urine cortisol, epinephrine, norepinephrine, and dopamine were obtained; heart rate and blood pressure were recorded continuously, and medication use, including requirements for opioids and vasoactive drugs, was recorded. Repeated-measures analysis was used to assess differences between study groups for plasma catecholamine and cortisol levels at each measurement time. RESULTS: In the control state-before the initiation of postoperative sedation in the ICU-no significant differences between study groups were observed for urine or plasma catecholamine or cortisol concentrations. During the ICU study period, for the first 6-8 h, significant differences were found between study groups SC and CP in plasma cortisol (SC = 28 +/- 15 mg/dl; CP = 19 +/- 12 mg/dl; estimated mean difference [EMD] = 9 mg/dl; P = 0.0004), plasma epinephrine (SC = 132 +/- 120 micrograms/ml; CP = 77 +/- 122 micrograms/ml; EMD = 69 micrograms/ml; P = 0.009), urine cortisol (SC = 216 +/- 313 micrograms/ml; CP = 93 +/- 129 micrograms/ml; EMD = 127 micrograms/ml; P = 0.007), urine dopamine (SC = 85 +/- 48 micrograms; CP = 52 +/- 43 micrograms; EMD = 32 micrograms; P = 0.002), urine epinephrine (SC = 7 +/- 8 micrograms; CP = 4 +/- 5 micrograms; EMD = 3 micrograms; P = 0.0009), and urine norepinephrine (SC = 24 +/- 14 mg; CP = 13 +/- 9 mg; EMD = 11 mg; P = 0.0004). Reductions in urine and plasma catecholamine and cortisol concentrations found for the CP group generally persisted during the 12-h propofol infusion period and then rapidly returned toward control (SC group) values after propofol was discontinued. Postoperative opioid use was reduced in the CP group (SC = 97%; CP = 49%; P = 0.001), as was the incidence of tachycardia (SC = 79%; CP = 60%; P = 0.04) and hypertension (SC = 58%; CP = 33%; P = 0.01), but the incidence of hypotension was increased (SC = 49%; CP = 81%; P = 0.001). CONCLUSIONS: Cardiopulmonary bypass graft surgery is associated with substantial increases in plasma and urine catecholamine and cortisol concentrations, which persist for 12 or more h. This hormonal response may be mitigated by a technique of intensive continuous 12-h postoperative sedation with propofol, which is associated with a decrease in tachycardia and hypertension and an increase in hypotension.

Aged↗
PubMed1995

Catecholamine and cortisol responses to lower extremity revascularization: correlation with outcome variables. Perioperative Ischemia Randomized Anesthesia Trial Study Group.

OBJECTIVE: To determine whether catecholamine and cortisol secretory responses to surgery contribute to postoperative complications. DESIGN: Prospective, randomized, case series. SETTING: A university hospital operating suite and surgical intensive care unit. PATIENTS: Sixty patients undergoing lower extremity vascular surgery. INTERVENTIONS: Patients were randomized to receive either epidural anesthesia/epidural opiate analgesia (regional anesthesia) or general anesthesia/intravenous patient-controlled analgesia (general anesthesia). MEASUREMENTS AND MAIN RESULTS: Anesthesia was managed according to a prospectively designed protocol. Hemodynamic parameters and plasma catecholamine concentrations were determined at specific intraoperative and postoperative time points. Intraoperative and postoperative urine samples were collected and analyzed for free cortisol concentrations. Outcomes evaluated were cardiac (nonfatal myocardial infarction and cardiac death) and surgical (graft occlusion). Mean arterial pressure during emergence from anesthesia and in the early postoperative period correlated positively with plasma norepinephrine concentration (p < .01). In addition, plasma catecholamine concentrations were higher in patients with postoperative hypertension. Plasma norepinephrine concentrations at the time of emergence from anesthesia and postoperatively were also higher in patients requiring repeat surgery for graft revision, thrombectomy, or amputation (p < .05). Multivariate analysis indicated that the norepinephrine concentration at the time of emergence, but not type of anesthesia, correlated with reoperation for graft occlusion, suggesting that the previously reported beneficial effect of regional anesthesia may be due to modulation of the stress response. Myocardial infarction or cardiac death occurred in three patients. These patients had markedly increased catecholamine concentrations. CONCLUSIONS: The catecholamine response to lower extremity vascular surgery contributes to the development of postoperative hypertension and may also be important in the development of thrombotic complications.

Adult↗
PubMedDate not supplied

Urinary catecholamine excretion in sexually abused girls.

OBJECTIVE: The objective of this study was to examine urinary catecholamine excretion in a self-selected sample of sexually abused and demographically matched control girls recruited from a prospective, longitudinal study. METHOD: Twenty-four--hour urinary catecholamine and metabolite concentrations of epinephrine, norepinephrine, dopamine, 3-methoxy-4-hydroxyphenylglycol, metanephrine, normetanephrine, vanillylmandelic acid, 3,4-dihydroxyphenylacetic acid, and homovanillic acid were measured in 12 sexually abused and 9 control girls, aged 8 to 15 years. Psychiatric profiles also were obtained. RESULTS: The abused subjects excreted significantly greater amounts of metanephrine, vanillylmandelic acid, homovanillic acid, and total catecholamine synthesis as measured by the sum of epinephrine, norepinephrine, dopamine, and their metabolites compared to values from control subjects. When the means of all significant biochemical measures were adjusted by the covariate effect of height, only homovanillic acid and group interaction remained significant. There were positive trends toward significantly higher urinary excretion of metanephrine, vanillylmandelic acid, and total catecholamine synthesis. Sexually abused girls also had a greater incidence of suicidal ideation, suicide attempts, and dysthymia than control girls. CONCLUSIONS: These findings support the idea that sexually abused girls show evidence of higher catecholamine functional activity compared with controls. The clinical significance of these findings in their similarity to the psychobiology of both post-traumatic stress disorder and major depressive disorder. Results from this pilot study may be of value in understanding the mechanisms of depressive and anxiety disorders and in the clinical treatment of maltreated children.

Attention Deficit Disorder with Hyperactivity↗
PubMed1998

Alterations in plasma neuropeptide Y immunoreactivity and catecholamine levels during surgical removal of pheochromocytoma.

BACKGROUND: Neuropeptide Y, an abundant neurohormone present with catecholamines in the adrenal medulla, is a potent non-adrenergic vasoconstrictor and a vascular growth factor. OBJECTIVE: To determine the mechanism of the release from, and possible role of neuropeptide Y in, pheochromocytomas, compared with those of catecholamines. METHODS: Plasma and tumour levels of neuropeptide Y-immunoreactivity (by, radioimmunoassay) and of noradrenaline and adrenaline (by a radioenzymatic method) in 29 patients (19 women and 10 men, aged 22-68 years) were measured during surgical removal of the tumour, during alpha-adrenergic and beta-adrenergic blockade. Arterial systemic blood samples were withdrawn before the ligation of the vessels supplying the tumour, during its surgical manipulations and after its removal, while haemodynamics was monitored. RESULTS: Plasma neuropeptide Y levels in 17 patients (58.6%, group I) significantly increased during manipulations of the pheochromocytoma and returned completely to normal after its removal. This response was independent of the plasma neuropeptide Y immunoreactivity manipulation and was correlated to increases in plasma noradrenaline (r = 0.638, P < 0.02) but not adrenaline levels. Manipulation-induced increases in plasma neuropeptide Y-immunoreactivity were associated with greater neuropeptide Y content in tumours (r = 0.508, P < 0.05) but neither plasma nor tumour levels of neuropeptide Y immunoreactivity were correlated to tumour mass. Plasma levels of neuropeptide Y immunoreactivity in the remaining 12 patients (41.4%, group II) remained unchanged throughout the experimental period, while levels of circulating catecholamine rose. In all, in spite of our attempt at complete adrenergic blockade, tumour manipulation elevated arterial blood pressure and these changes were significantly correlated to increases in levels of catecholamines in patients in both groups but also to plasma neuropeptide Y immunoreactivity in patients in group I. CONCLUSION: Pheochromocytomas exhibit different patterns of secretion. For about half of the patients either the secretion of neuropeptide Y is uncoupled from that of catecholamines or its secretion could be obscured by an increase in degradation of neuropeptide Y to inactive fragments undetectable by radioimmunoassay.

Adult↗
PubMedDate not supplied

Alpha-adrenoceptor blockade by phentolamine causes beta-adrenergic vasodilation by increased catecholamine release due to presynaptic alpha-blockade.

We tested whether the alpha 1- and alpha 2-blocking agent phentolamine can be used to assess the contribution of alpha-adrenergic constriction in circulatory control. In 15 conscious dogs at rest, phentolamine (2 mg/kg i.v.) caused hypotension (-17 mm Hg mean arterial pressure), vasodilation (-29% total peripheral resistance), tachycardia, and an increase in cardiac output, oxygen consumption, and plasma catecholamines. Following beta-adrenoceptor blockade (2 mg/kg i.v. nadolol), phentolamine still produced hypotension and increased plasma catecholamine levels, but neither vasodilation nor augmented oxygen consumption. During beta-blockade, phentolamine caused a 28-fold decrease in the vasoconstrictor response to norepinephrine infusions. An equihypotensive dosage of the alpha 1-adrenoceptor blocking agent prazosin (1.2 mg/kg i.v.) did not elevate heart rate, cardiac output, plasma catecholamines, or oxygen consumption. The prazosin-induced vasodilation was not attenuated by prior beta-blockade, in contrast to the phentolamine-induced vasodilation. It is concluded that phentolamine increased catecholamine release by presynaptic alpha 2-blockade, thereby suppressing the autoinhibition of transmitter release. This excess of catecholamines causes a rise of oxygen consumption and vasodilation by beta-adrenergic stimulation. Under beta-blockade, this excess competitively counteracts the postsynaptic vascular alpha-blockade. The combination of pre- and postsynaptic effects invalidates the use of phentolamine in the assessment of alpha-adrenoceptor-mediated vasoconstrictor tone.

Animals↗
PubMed1997

Effects of nitroprusside and nicorandil on catecholamine secretion and calcium mobilization in cultured bovine adrenal chromaffin cells.

The effects of nitroprusside and nicorandil on catecholamine secretion and free intracellular Ca2+ ([Ca2+]i) mobilization in bovine adrenal chromaffin cells were studied to evaluate the role of the nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway in the regulation of a [Ca2+]i-dependent secretory process. These effects were compared with those of nifedipine, a typical voltage-dependent Ca2+ channel blocker. Carbachol produced a rapid increase followed by a sustained increase of [Ca2+]i (Ca2+ transient) in cultured bovine adrenal chromaffin cells. Both nitroprusside and nicorandil accelerated the decrease in [Ca2+]i without changing the peak values of the initial [Ca2+]i increase of Ca2+ transient. These drugs, however, did not affect carbachol-induced catecholamine secretion, suggesting that secretion is related to the initial [Ca2+]i increase and not to a late sustained [Ca2+]i increases. However, nifedipine reduced the peak and duration of carbachol-induced [Ca2+]i increases and decreased the secretion of catecholamines. Diethylamine/NO complex, an NO donor, and dibutyryl-cGMP produced similar changes in Ca2+ transient and did not alter catecholamine secretion, suggesting that the effects of nitroprusside and nicorandil were mediated by the NO/cGMP pathway. These results indicated that the pattern of Ca2+ transient, especially the initial increase in [Ca2+]i, is important in secretion of catecholamine.

Adrenal Medulla↗
PubMed1997

Exercise effect on canine and miniswine cardiac catecholamines and enkephalins.

Chronic exercise changes cardiac function and responsiveness to autonomic control. Catecholamines and enkephalins are neuroendocrine transmitters involved in autonomic regulation and signaling. We hypothesized that intermittent increased sympathetic stimulation caused by exercise training would decrease cardiac catecholamine and enkephalin content. Dogs and miniswine were exercise trained and hearts extracted for catecholamine and enkephalin measurements. Atrial catecholamine content is greater than ventricular content in dog heart which is in keeping with the greater atrial neuronal density. In contrast, porcine epinephrine content was evenly distributed across heart sections and norepinephrine content was greater on the right side than the left. Changes in miniswine and dog heart catecholamine content after exercise training were different. Canine cardiac norepinephrine content decreased and porcine norepinephrine content increased. This indicates a difference in cardiac adrenergic control in miniswine versus canines. Methionine-enkephalin (met-enk) distribution across canine heart is uniform, unlike the miniswine, where the atria contain more than the ventricles. Proenkephalin processing produces four met-enk sequences and one met-enk-arg-phe; despite this, ventricles of both species contain more met-enk-arg-phe immunoreactivity than met-enk. Therefore, proenkephalin processing is incomplete in heart tissue. Exercise training in the dog resulted in decreased cardiac met-enk, decreased left atrial met-enk-arg-phe, and increased ventricular met-enk-arg-phe. Porcine cardiac enkephalin concentration was unchanged by training. The changes in the enkephalins may be explained by changes in proenkephalin processing and/or release. Met-enk-arg-phe is particularly good at modulating vagal stimulation of the canine heart. The changes in tissue content seen after exercise training may be a result of the exercise-induced change in autonomic tone to the heart. These data suggest species dependent changes in autonomic regulation.

Analysis of Variance↗
PubMed1992

Catecholamine response to laryngoscopy and intubation. The influence of three different drug combinations commonly used for induction of anaesthesia.

The haemodynamic response and changes in plasma catecholamine concentrations associated with laryngoscopy and tracheal intubation were compared during anaesthesia employing three strictly standardised techniques with commonly used drug combinations. Thirty-six patients were investigated consecutively resulting in 12 patients in each of three study groups. Anaesthesia was induced with thiopentone 5 mg.kg-1 (group 1), fentanyl 6 micrograms.kg-1 with thiopentone 5 mg.kg-1 (group 2), or midazolam 0.2 mg.kg-1 with fentanyl 6 micrograms.kg-1 (group 3). Undesirable changes in haemodynamic effects and an elevation of plasma catecholamine concentrations during laryngoscopy and intubation occurred in group 1. Heart rate and mean arterial pressure increased significantly (34% and 23% respectively). Noradrenaline concentration increased by a maximum of 147%. The addition of fentanyl (groups 2 and 3) attenuated the adverse haemodynamic response and elevation of plasma catecholamine concentrations; heart rate and mean arterial pressure did not differ from pre-intubation values and plasma catecholamine concentrations decreased steadily. Substitution of thiopentone by midazolam in combination with fentanyl abolished the adverse haemodynamic response and modified the increase in plasma catecholamine concentrations. 'High-dose' opioid anaesthesia is not necessary to produce optimal conditions during laryngoscopy and intubation.

Adolescent↗
PubMed1993

The effects of the COMT inhibitor entacapone on haemodynamics and peripheral catecholamine metabolism during exercise.

1. Catechol-O-methyltransferase (COMT) inhibition might be assumed to potentiate the effects of circulating catecholamines, particularly under conditions of enhanced catecholamine release. 2. The purpose of the present study was to establish whether the novel COMT inhibitor, entacapone, changes haemodynamic responses and catecholamine metabolism during exercise. 3. Entacapone was given orally to 12 healthy male subjects (age 23-30 years) in increasing single doses from 0 mg (control day) to 200 mg. A submaximal exercise test was performed on a bicycle ergometer, and blood pressure, heart rate and ECG were recorded. The concentrations of noradrenaline, adrenaline, DHPG (3,4-dihydroxyphenylglycol), MHPG (3-methoxy-4-hydroxyphenyl-glycol) and, DOPAC (3,4-dihydroxyphenylacetic acid) in plasma were determined. 4. Entacapone did not influence haemodynamics or ECG at rest or during exercise. 5. Entacapone did not influence plasma catecholamine levels, either at rest or during exercise. However, it altered the metabolic profile of catecholamines, which was shown by increases in the plasma concentrations of the monoamine oxidase-dependent metabolites DHPG (by up to 100%) and DOPAC (by up to 53%), and by a decrease of the COMT-dependent metabolite MHPG (by up to 29%).

Administration, Oral↗