Showing papers on "Norepinephrine (medication) published in 2000"

Effect of norepinephrine on the outcome of septic shock.

Abstract: Objective: Despite increasingly sophisticated critical care, the mortality of septic shock remains elevated. Accordingly, care remains supportive. Volume resuscitation combined with vasopressor support remains the standard of care as adjuvant therapy, and many consider dopamine to be the pressor of choice. Because of fear of excessive vasoconstriction, norepinephrine is considered to be deleterious. The present study was designed to identify factors associated with outcome in a cohort of septic shock patients. Special attention was paid to hemodynamic management and to the choice of vasopressor used, to determine whether the use of norepinephrine was associated with increased mortality. Design: Prospective, observational, cohort study. Setting: Intensive care unit of a university hospital. Patients: Ninety-seven adult patients with septic shock. Measurements and Main Results: Data from these patients were examined to select variables independently and significantly associated with outcome during the hospital stay. Nineteen clinical, biological, and hemodynamic variables were collected at study entry or during the first 48 ‐72 hrs and analyzed for each patient. A stepwise logistic regression analysis and a model building strategy were used to identify variables independently and significantly associated with outcome. The overall hospital mortality was 73% (71 patients). Five variables were significantly associated with outcome. One factor was strongly associated with a favorable outcome: the use of norepinephrine as part of the hemodynamic support of the patients. The 57 patients who were treated with norepinephrine had significantly lower hospital mortality (62% vs. 82%, p 4 mmol/L (91% vs. 63%, p < .01; relative risk 5 1.60; 95% confidence interval 5 1.27‐1.84). Conclusions: Our results indicate that the use of norepinephrine as part of hemodynamic management may influence outcome favorably in septic shock patients. The data contradict the notion that norepinephrine potentiates end-organ hypoperfusion, thereby contributing to increased mortality. However, the present study suffers from some limitation because of its nonrandomized, openlabel, observational design. Hence, a randomized clinical trial is needed to clearly establish that norepinephrine improves mortality of patients with septic shock, as compared with high-dose dopamine or epinephrine. Pneumonia as the cause of septic shock, high blood lactate concentration, and low urine output on admission are strong indicators of a poor prognosis. Multiple organ failure is confirmed as a reliable predictor of mortality in septic patients. (Crit Care Med 2000; 28:2758 ‐2765)

Reduced brain norepinephrine and dopamine release in treatment-refractory depressive illness: evidence in support of the catecholamine hypothesis of mood disorders.

Abstract: Background: The etiology of depressive illness has been linked with brain monoaminergic neuronal dysfunction, yet the development of sensitive markers of endogenous depression has proven difficult. Methods: Using catheters placed in an internal jugular vein, we estimated the release of brain monoamine neurotransmitters in 19 healthy volunteers and in 9 patients with nonbipolar depressive illness refractory to medication at rest and following intravenous desipramine hydrochloride. Venoarterial plasma concentration gradients were used to quantify the amount of neurotransmitters stemming from the brain. Cerebral oxidative metabolism was assessed concurrently from measurements of oxygen and carbon dioxide gas exchange via the process of regional indirect calorimetry. Results: The brains of these patients exhibited reduced venoarterial norepinephrine (4.0±2.7 nmol/L vs 0.7±1.3 nmol/L) and homovanillic acid concentration gradients (8.3±7.8 nmol/L vs 3.1±1.9 nmol/L), and used an energy source other than glucose. Internal jugular 5-hydroxyindoleacetic acid concentration gradients were not reduced in the patients with depressive illness. While both the reduction in norepinephrine turnover and the defect in cerebral metabolism were normalized following pharmacological blockade of the norepinephrine transporter with desipramine, paradoxically it was the brain’s turnover of dopamine that bore a significant relation to the patients’ clinical status (rs=0.79, P=.02). The positive nature of this relationship remains difficult to reconcile. Conclusions: In accordance with the monoamine hypothesis, a deficit in brain norepinephrine and dopamine exists in patients with depressive illness. Moreover, the brains of these patients use an energy source other than glucose, a situation that is normalized following the acute pharmacological blockade of the norepinephrine transporter with the tricyclic antidepressant, desipramine.

The Hemodynamic and Adrenergic Effects of Perioperative Dexmedetomidine Infusion after Vascular Surgery

Abstract: UNLABELLED: We tested dexmedetomidine, an alpha(2) agonist that decreases heart rate, blood pressure, and plasma norepinephrine concentration, for its ability to attenuate stress responses during emergence from anesthesia after major vascular operations. Patients scheduled for vascular surgery received either dexmedetomidine (n = 22) or placebo (n = 19) IV beginning 20 min before the induction of anesthesia and continuing until 48 h after the end of surgery. All patients received standardized anesthesia. Heart rate and arterial blood pressure were kept within predetermined limits by varying anesthetic level and using vasoactive medications. Heart rate, arterial blood pressure, and inhaled anesthetic concentration were monitored continuously; additional measurements included plasma and urine catecholamines. During emergence from anesthesia, heart rate was slower with dexmedetomidine (73 +/- 11 bpm) than placebo (83 +/- 20 bpm) (P = 0.006), and the percentage of time the heart rate was within the predetermined hemodynamic limits was more frequent with dexmedetomidine (P < 0.05). Plasma norepinephrine levels increased only in the placebo group and were significantly lower for the dexmedetomidine group during the immediate postoperative period (P = 0.0002). We conclude that dexmedetomidine attenuates increases in heart rate and plasma norepinephrine concentrations during emergence from anesthesia. IMPLICATIONS: The alpha(2) agonist, dexmedetomidine, attenuates increases in heart rate and plasma norepinephrine concentrations during emergence from anesthesia in vascular surgery patients.

The Mammalian Neuroendocrine Hormone Norepinephrine Supplies Iron for Bacterial Growth in the Presence of Transferrin or Lactoferrin

Abstract: Norepinephrine stimulates the growth of a range of bacterial species in nutritionally poor SAPI minimal salts medium containing 30% serum. Addition of size-fractionated serum components to SAPI medium indicated that transferrin was required for norepinephrine stimulation of growth of Escherichia coli. Since bacteriostasis by serum is primarily due to the iron-withholding capacity of transferrin, we considered the possibility that norepinephrine can overcome this effect by supplying transferrin-bound iron for growth. Incubation with concentrations of norepinephrine that stimulated bacterial growth in serum-SAPI medium resulted in loss of bound iron from iron-saturated transferrin, as indicated by the appearance of monoferric and apo- isoforms upon electrophoresis in denaturing gels. Norepinephrine also caused the loss of iron from lactoferrin. The pharmacologically inactive metabolite norepinephrine 3-O-sulfate, by contrast, did not result in iron loss from transferrin or lactoferrin and did not stimulate bacterial growth in serum-SAPI medium. Norepinephrine formed stable complexes with transferrin, lactoferrin, and serum albumin. Norepinephrine-transferrin and norepinephrine-lactoferrin complexes, but not norepinephrine-apotransferrin or norepinephrine-albumin complexes, stimulated bacterial growth in serum-SAPI medium in the absence of additional norepinephrine. Norepinephrine-stimulated growth in medium containing 55Fe complexed with transferrin or lactoferrin resulted in uptake of radioactivity by bacterial cells. Moreover, norepinephrine-stimulated growth in medium containing [3H]norepinephrine indicated concomitant uptake of norepinephrine. In each case, addition of excess iron did not affect growth but significantly reduced levels of radioactivity (55Fe or 3H) associated with bacterial cells. A role for catecholamine-mediated iron supply in the pathophysiology of infectious diseases is proposed.

Inactivation of catecholamines by superoxide gives new insights on the pathogenesis of septic shock.

Abstract: A major feature of septic shock is the development of a vascular crisis characterized by nonresponsiveness to sympathetic vasoconstrictor agents and the subsequent irreversible fall in blood pressure. In addition, sepsis, like other inflammatory conditions, results in a large increase in the production of free radicals, including superoxide anions (O2⨪) within the body. Here we show that O2⨪ reacts with catecholamines deactivating them in vitro. Moreover, this deactivation would appear to account for the hyporeactivity to exogenous catecholamines observed in sepsis, because administration of a superoxide dismutase (SOD) mimetic to a rat model of septic shock to remove excess O2⨪ restored the vasopressor responses to norepinephrine. This treatment with the SOD mimetic also reversed the hypotension in these animals; suggesting that deactivation of endogenous norepinephrine by O2⨪ contributes significantly to this aspect of the vascular crisis. Indeed, the plasma concentrations of both norepinephrine and epinephrine in septic rats treated with the SOD mimetic were significantly higher than in untreated rats. Interestingly, the plasma concentrations for norepinephrine and epinephrine were inversely related to the plasma concentrations of adrenochromes, the product of the autoxidation of catecholamines initiated by O2⨪. We propose, therefore, that the use of a SOD mimetic represents a new paradigm for the treatment of septic shock. By removing O2⨪, exogenous and endogenous catecholamines are protected from autoxidation. As a result, both hyporeactivity and hypotension are reversed, generation of potentially toxic adrenochromes is reduced, and survival rate is improved.

Increased Vascular Adrenergic Vasoconstriction and Decreased Vasodilation in Blacks: Additive Mechanisms Leading to Enhanced Vascular Reactivity

Abstract: Blood pressure reactivity is enhanced in young black subjects through mechanisms that are poorly understood. We compared alpha-adrenergic-mediated vasoconstrictor and ss-adrenergic vasodilator sensitivity and their relation to sympathetic activity in blacks and whites. Ten healthy black (age, 29.9+/-2.4 years) and 10 white (age, 28.3+/-1.9 years) men were studied. Forearm blood flow was measured with strain-gauge plethysmography after the intrabrachial artery administration of phenylephrine (1.25 to 20 microgram/min) and isoproterenol (60 and 400 ng/min) after application of lower-body negative pressure and after a cold pressor test. Forearm and systemic norepinephrine spillover were measured with a radioisotope dilution technique. alpha-Adrenergic vasoconstriction was markedly increased (ANOVA P=0.008) and ss-adrenergic vasodilation decreased (ANOVA P=0.02) in blacks. Phenylephrine (10 microgram/min) decreased forearm blood flow by 58.0+/-2.5% in blacks but only by 26.6+/-6.0% in whites (P<0.001). Vasoconstrictor response to endogenous norepinephrine, stimulated by a cold pressor test, resulted in a higher forearm vascular resistance in blacks than in whites (107.3+/-13 versus 64.8+/-13 mm Hg. mL(-)(1). 100 mL(-)(1), P=0.03). There were no significant ethnic differences in basal or stimulated forearm or systemic norepinephrine spillover. Increased vasoconstrictor and decreased vasodilator responses in blacks were not correlated. Increased sympathetically mediated vascular tone caused by enhanced vasoconstriction and attenuated vasodilation, effects that would be additive, and not increased sympathetic activity could enhance vascular reactivity and may play a role in the pathogenesis of hypertension in blacks.

Abnormalities of Cardiac Sympathetic Innervation in Arrhythmogenic Right Ventricular Cardiomyopathy Quantitative Assessment of Presynaptic Norepinephrine Reuptake and Postsynaptic β-Adrenergic Receptor Density With Positron Emission Tomography

Abstract: Background—The frequent provocation of ventricular tachycardia by stress or catecholamines and the efficacy of antiarrhythmic drugs with antiadrenergic properties suggest an involvement of the cardiac adrenergic system in arrhythmogenesis in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). Previous studies demonstrated abnormalities of the presynaptic uptake-1 assessed by 123I-MIBG–single-photon emission computed tomography. Methods and Results—This study investigated neuronal reuptake of norepinephrine (uptake-1) and β-adrenergic receptor density in 8 patients with ARVC and 29 age-matched control subjects. All subjects underwent positron emission tomography with the volume of distribution (Vd) of [11C]hydroxyephedrine (11C-HED) used to assess presynaptic norepinephrine reuptake, the maximum binding capacity (Bmax) of [11C]CGP-12177 (11C-CGP-12177) to assess postsynaptic β-adrenergic receptor density, and [15O]H2O for quantification of myocardial blood flow. Patients with ARVC demonst...

Norepinephrine facilitates inhibitory transmission in substantia gelatinosa of adult rat spinal cord (part 2): effects on somatodendritic sites of GABAergic neurons.

Abstract: Background It has been reported previously that norepinephrine, when applied to the spinal cord dorsal horn, excites a subpopulation of dorsal horn neurons, presumably inhibitory interneurons. In the current study, the authors tested whether norepinephrine could activate inhibitory interneurons, specifically those that are "GABAergic." Methods A transverse slice was obtained from a segment of the lumbar spinal cord isolated from adult male Sprague-Dawley rats. Whole-cell patch-clamp recordings were made from substantia gelatinosa neurons using the blind patch-clamp technique. The effects of norepinephrine on spontaneous GABAergic inhibitory postsynaptic currents were studied. Results In the majority of substantia gelatinosa neurons tested, norepinephrine (10-60 microM) significantly increased both the frequency and the amplitude of GABAergic inhibitory postsynaptic currents. These increases were blocked by tetrodotoxin (1 microM). The effects of norepinephrine were mimicked by the alpha1-receptor agonist phenylephrine (10-80 microM) and inhibited by the alpha1-receptor-antagonist WB-4101 (0.5 microM). Primary-afferent-evoked polysynaptic excitatory postsynaptic potentials or excitatory postsynaptic currents in wide-dynamic-range neurons of the deep dorsal horn were also attenuated by phenylephrine (40 microM). Conclusion The observations suggest that GABAergic interneurons possess somatodendritic alpha1 receptors, and activation of these receptors excites inhibitory interneurons. The alpha1 actions reported herein may contribute to the analgesic action of intrathecally administered phenylephrine.

Reducing Cardiac Filling Pressure Lowers Norepinephrine Spillover in Patients With Chronic Heart Failure

Abstract: Background—We studied the cardiac sympathetic response to selective unloading of cardiopulmonary baroreceptors in subjects with normal left ventricular (LV) function and congestive heart failure (CHF). Methods and Results—Eight patients with normal LV function (age 57±5 years, ejection fraction 58±2%) and 8 patients with CHF (age 60±2 years; ejection fraction 19±2%) were studied. Instrumentation consisted of an arterial line, a pulmonary artery catheter, and a coronary sinus thermodilution catheter. The radiotracer technique was used for measurement of cardiac norepinephrine spillover (CANESP) and total-body norepinephrine spillover. Lower-body negative pressure (LBNP) was applied at 2 levels: nonhypotensive and hypotensive LBNP. Nonhypotensive LBNP reduced filling pressures significantly in both groups. Arterial pressure did not change. This reduction in filling pressures caused a significant reduction in CANESP in the CHF group (from 167±53 to 125±37 pmol/min, P<0.05) but no change in the normal LV func...

Cytokine production by naive and primary effector CD4+ T cells exposed to norepinephrine.

Abstract: We recently showed that clones of Th1 cells, but not Th2 cells, expressed a functional beta-2-adrenergic receptor (beta2AR) and that either norepinephrine or the beta2AR agonist terbutaline stimulated this receptor to modulate the level of Th1 cytokines produced. In the present study, we show that norepinephrine and terbutaline stimulate the beta2AR to decrease the level of IL-2 produced by freshly isolated murine splenic naive CD4+ T cells from either Balb/C or DO11.10 transgenic mice and activated polyclonally with anti-CD3 and anti-CD28 mAbs. In contrast, the level of cytokines produced by primary effector Th1 and Th2 cells were unaffected when norepinephrine, terbutaline, or cAMP analogs were added at the time of restimulation. These results suggest that a diversity exists among CD4+ T-cell subsets with respect to the level of adrenergic receptor expression, responsiveness to cAMP, stage of cell differentiation, or a combination of the above.

Gut-derived norepinephrine plays a critical role in producing hepatocellular dysfunction during early sepsis.

Abstract: Although plasma norepinephrine (NE) increases and hepatocellular function is depressed during early sepsis, it is unknown whether gut is a significant source of NE and, if so, whether gut-derived N...

Angiotensin for septic shock unresponsive to noradrenaline

Abstract: Two children with severe septic shock are reported. One had meningococcal septicaemia and the other Escherichia coli septicaemia. They remained hypotensive despite high concentrations of conventional inotropes and vasopressors. In one child, using a pulmonary artery catheter, extended haemodynamic variables were measured. To restore blood pressure, in both cases, an infusion of angiotensin II was used; there was significant improvement in clinical status, resulting in a rapid reduction in the concentration of inotropes required. Both patients successfully survived their septic episodes. Angiotensin II in cases of severe refractory septic hypotension in the paediatric population offers an extra therapeutic manoeuvre.

Selective suppression of horizontal propagation in rat visual cortex by norepinephrine

Abstract: The release of norepinephrine in the cerebral cortex from axon terminals of locus coeruleus neurons was suggested to be involved in the control of attention. Accumulating data indicate that the responses of cortical neurons are varied when norepinephrine is applied iontophoretically in the vicinity of the cells being recorded. However, it is not known how the pattern of excitatory propagation is modified when norepinephrine is applied over a wide area in the visual cortex. By applying optical imaging to rat visuocortical slices, we found a new mode of norepinephrine action; a prominent suppression of the horizontal propagation in layers II/III. This action of norepinephrine was confirmed by the simultaneous recording of field potentials from multiple sites by use of a multi-electrode dish. Furthermore, our electrophysiological recordings showed that this norepinephrine action is exerted through suppression of excitatory neural transmission and enhancement of inhibitory transmission to the pyramidal neurons in these layers. Because the release of norepinephrine in the visual cortex is regulated by the level of attention, the neural basis of visual attention may relate partially to the suppression of the integration of visual information by norepinephrine resulting in a state-dependent restructuring of the receptive field.

Vasopressin as an alternative to norepinephrine in the treatment of milrinone-induced hypotension

Abstract: Objective:To determine whether vasopressin could be effective in treating the hypotension associated with phosphodiesterase III inhibition. Phosphodiesterase III inhibitors are cardiotonic agents that increase myocardial contractility and decrease vascular smooth muscle tone. The vasodilatory effect

Acute cold exposure decreases plasma leptin in women.

Abstract: We investigated whether cold exposure affects circulating leptin in humans. Five women (age, 32 ± 4 years ; body mass index, 23.1 ± 1.7 kg/m2 ) participated in two separate trials. Subjects sat at room temperature ([RT] 24.8° ± 0.3°C) or in the cold (6.3° ± 0.5°C) for 90 minutes. During RT exposure, plasma leptin and norepinephrine were unchanged over time. Cold exposure significantly decreased plasma leptin by 14%, 17%, and 22% at 30, 60, and 90 minutes, respectively (temperature x time interaction, P P P

Norepinephrine mediates glucoprivic-induced increase in GABA in the ventromedial hypothalamus of rats.

Abstract: Noradrenergic mechanisms in the hypothalamus may be involved in counterregulatory responses to glucoprivic episodes. After 2-deoxy-d-glucose (2-DG; 1.2 mmol/kg iv), extracellular norepinephrine (NE...

Cardiovascular and neuroendocrine responses to water immersion in compensated heart failure

Abstract: The hypothesis was tested that cardiovascular and neuroendocrine (norepinephrine, renin, and vasopressin) responses to central blood volume expansion are blunted in compensated heart failure (HF). ...

α1-Adrenoceptor subtypes in rat renal resistance vessels : In vivo and in vitro studies

Abstract: This study provides new information about the relative importance of different α1-adrenoceptors during norepinephrine (NE) activation in rat renal resistance vessels. In Sprague-Dawley rats, we mea...

Cerebral blood flow and metabolism in severe brain injury: the role of pressure autoregulation during cerebral perfusion pressure management

Abstract: Objective: To ascertain if norepinephrine can be used as part of the cerebral perfusion pressure (CPP) management to increase arterial blood pressure (MAP) without causing cerebral hyperemia after severe head injury (HI).¶Design: Prospective, interventional study.¶Setting: Intensive care unit in a university hospital.¶Patients: Twelve severely HI patients; median Glasgow Coma Scale was 6 (range 3–8).¶Interventions: CPP management ( = 70 mmHg). Pressure autoregulation (assessed by norepinephrine infusion) was defined intact if %CPP/%CVR ≤ 2.¶Results: Cerebral blood flow (CBF: Xe133 inhalation technique), jugular bulb oxygen saturation (SjO2) and transcranial Doppler (TCD) were recorded during the test. Norepinephrine increased CPP by 33 % ( ± 4). Autoregulation was found to be intact in ten patients and defective in two. In the ten patients with preserved autoregulation, CBF decreased from 31 ± 3 to 28 ± 3 ml/100 g/min; in the two patients with impaired autoregulation CBF increased respectively from 16 to 35 and from 21 to 70 ml/100 g/min. SjO2 did not change significantly from baseline. TCD remained within the normal range.¶Conclusions: During CPP management norepinephrine can be used to increase MAP without potentiating hyperemia if pressure autoregulation is preserved. The assessment of pressure autoregulation should be considered as a guide for arterial pressure-oriented therapy after HI.

Evidence of UCP1-independent regulation of norepinephrine-induced thermogenesis in brown fat.

Abstract: To study the thermal response of interscapular brown fat (IBF) to norepinephrine (NE), urethan-anesthetized rats (1.2 g/kg ip) maintained at 28–30°C received a constant venous infusion of NE (0–2 ×...