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11.
Akiko Arata H. Onimaru Ikuo Homma 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1998,119(4):399-408
We analysed the modulation of respiratory neurons by adrenaline or noradrenaline (NA) in a newborn rat brainstem-spinal cord
preparation. Adrenaline or NA caused a dose-dependent depression of the respiratory rhythm and induced C4 spinal tonic discharges.
The inhibitory effect of adrenaline (ED50=0.5 μM) on the respiratory rhythm was stronger than NA (ED50=5 μM). The adrenaline respiratory rhythm depression was partially blocked by the α1-antagonist prazosin or by the α2-antagonist yohimbine. The C4 tonic discharge elicited by adrenaline was blocked by the α1-antagonist prazosin. The direct effects of adrenaline on pre-inspiratory (Pre-I) neurons were examined in a synaptic blockade
solution (low Ca), and fifty-six percent of Pre-I neurons were found to continue firing. In low-Ca solution, Pre-I neurons
were excited (n=29 of 39) or depressed (n=5 of 39) by adrenaline, and excited by α1-agonist phenylephrine or depressed by α2-agonist clonidine. These results suggest that the respiratory rhythm depression under intact network conditions is mediated
by some other inhibitory system. The inhibitory effect of adrenaline on the respiratory rhythm was partially blocked by the
GABAA-antagonists bicuculline or picrotoxin, but not by the GABAB-antagonist phaclofen. The present results suggest that: (1) respiratory rhythm generation is more sensitive to adrenaline
than NA through α-adrenergic action of adrenaline; (2) the activity of Pre-I neurons could be directly regulated by excitation
via α1-receptors and inhibition via α2-receptors; and (3) the depression of the respiratory rhythm by adrenaline is partly mediated by GABAAergic neurons.
Received: 8 April 1997 / Accepted: 6 October 1997 相似文献
12.
Plasma testosterone and catecholamine responses to physical exercise of different intensities in men
D. JeŽová M. Vigaš P. Tatár R. Kvetňanský K. Nazar H. Kaciuba-UŚcilko S. Kozlowski 《European journal of applied physiology》1985,54(1):62-66
Summary Plasma testosterone, noradrenaline, and adrenaline concentrations during three bicycle ergometer tests of the same total work output (2160 J·kg–1) but different intensity and duration were measured in healthy male subjects. Tests A and B consisted of three consecutive exercise bouts, lasting 6 min each, of either increasing (1.5, 2.0, 2.5 W·kg–1) or constant (2.0, 2.0, 2.0 W·kg–1) work loads, respectively. In test C the subjects performed two exercise bouts each lasting 4.5 min, with work loads of 4.0 W·kg–1. All the exercise bouts were separated by 1-min periods of rest.Exercise B of constant low intensity resulted only in a small increase in plasma noradrenaline concentration. Exercise A of graded intensity caused an increase in both catecholamine levels, whereas, during the most intensive exercise C, significant elevations in plasma noradrenaline, adrenaline and testosterone concentrations occurred. A significant positive correlation was obtained between the mean value of plasma testosterone and that of adrenaline as well as noradrenaline during exercise.It is concluded that both plasma testosterone and catecholamine responses to physical effort depend more on work intensity than on work duration or total work output.This work was performed within the Scientific Exchange Programme between the Institute of Experimental Endocrinology, Slovak Academy of Sciences in Bratislava and Medical Research Centre, Polish Academy of Sciences, Warsaw/Project 10.4/ 相似文献
13.
Adrenaline was determined in injections containing procaine in a 1000-fold excess by reversed-phase high-performance liquid chromatography using UV detection at 205 nm and aqueous sulphuric acid (100 μmol/l) as eluent. The relative standard deviation was 2.1%, and the method was selective in the presence of adrenaline degradation products. Changes of the capacity factor with pH and ionic strength of the eluent were studied, and a simple model is suggested to explain the retention data. 相似文献
14.
Summary Isolated rat hepatocytes were incubated with 0.05 mol/l or 0.2 mol/l 3H-(–)-noradrenaline or 0.05 mol/l 3H-(–)-adrenaline for 15 min and the content of amines as well as the formation of metabolites was measured.The removal Of both amines from the incubation medium was quantitatively similar, and mainly due to metabolism (which represented 96% of the removal of 3H-adrenaline and 98% of the removal of 3H-noradrenaline). O-methylation predominated for 3H-adrenaline: O-methylated and deaminated metabolites (3H-OMDA) and 3H-metanephrine (3H-MN) were the most abundant metabolites, accounting for 63% and 34% of total metabolite formation, respectively. Deamination predominated for 3H-noradrenaline: 3H-OMDA and 3H-dihydroxymandelic acid (3H-DOMA) were the most abundant metabolites, representing respectively 56% and 36% of total metabolite formation. The following activities of monoamine oxidase and catechol-O-methyl transferase were determined for 3H-noradrenaline: kCOMT 0.70±0.15 min–1 and kMAO 2.27±0.14 min–1 In experiments with 3H-noradrenaline, inhibition of monoamine oxidase reduced the formation of 3H-OMDA and deaminated metabolites [3H-dihydroxyphenylglycol (3H-DOPEG) and 3H-DOMA] and increased the formation of 3H-normetanephrine (3H-NMN). Inhibition of catechol-O-methyl transferase, On the Other hand, decreased 3H-NMN and increased 3H-DOPEG formation. When both enzymes were inhibited, the formation of all metabolites was strongly reduced but surprisingly there was no accumulation of 3H-amines in the cells, as the cell: medium ratio for 3H-noradrenaline or 3H-adrenaline was about unity. In experiments with either 3H-noradrenaline or 3H-adrenaline, specific inhibitors of either uptake, or uptake2 produced discrete effects, slightly decreasing the formation of 3H-OMDA and 3H-NMN or 3H-MN, and having no effect on 3H-amine content of the cells. Additional experiments were carried Out with rat liver slices incubated for 15 min with 3H-noradrenaline 0.2 mol/l. The pattern of metabolism of 3H-noradrenaline (3H-OMDA and 3H-DOMA were the most abundant metabolites) as well as the degree of metabolism of the amine removed from the incubation medium (91% of the removal) were similar to those of the isolated cells. Likewise, there was no accumulation of intact 3H-noradrenaline in the tissue. Moreover, the results obtained with enzyme inhibitors as wells as with uptake inhibitors were similar to those obtained with hepatocytes.In conclusion, isolated hepatocytes remove and metabolize catecholamines very efficiently, being one of the most active systems studied in this respect. Uptake1 and uptake2 are responsible for part of the removal of catecholamines by hepatocytes; the system(s) involved in the remaining removal seem(s) to be active, but possess(es) characteristics that do not allow us to characterize it (them) either as uptake1 or uptake2.Abbreviations COMT
catechol-O-methyl transferase
- DOMA
3,4-dihydroxymandelic acid
- DOPEG
3,4-dihydroxyphenylglycol
- HEPES
4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
- MAO
monoamine oxidase
- MN
metanephrine
- NMN
normetanephrine
- OMDA
O-methylated and deaminated metabolites (i.e., MOPEG = 4hydroxy-3-methoxyphenylglycol and VMA = 4-hydroxy-3-methoxymandelic acid)
Supported by Programa STRIDE (STRDA/P/SAU/259/92)PhD student with a grant from JNICT (Programa Ciência)
Correspondence to: F. Martel at the above address 相似文献
15.
N. Singewald C. Schneider A. Philippu 《Naunyn-Schmiedeberg's archives of pharmacology》1993,348(3):242-248
Summary Effects of carotid occlusion and drugs applied intravenously on the release of endogenous catecholamines in the locus coeruleus of cats anaesthetized with pentobarbital or chloralose were investigated. The locus coeruleus was superfused bilaterally with artificial cerebrospinal fluid through push-pull cannulae inserted stereotaxically. Dopamine, noradrenaline and in some experiments also adrenaline were determined radioenzymatically in the superfusate.Under pentobarbital anaesthesia, a bilateral carotid occlusion increased the release rate of noradrenaline in the locus coeruleus, while the release of dopamine was decreased. These changes were due to the fall of blood pressure in the carotid sinus caused by the occlusion. Loading of baroreceptors by elevating blood pressure with phenylephrine (10 g·kg–1·min–1, i.v. infusion) was accompanied by a decreased release of noradrenaline in the locus coeruleus. This decrease in noradrenaline release was not detected in the caudal aspect of the locus coeruleus. Under chloralose anaesthesia, phenylephrine diminished the release rate of noradrenaline to about the same extent as under pentobarbital anaesthesia. The release rate of adrenaline was also decreased. A prolonged infusion of phenylephrine led to a prolonged pressor response associated with a sustained decrease in the noradrenaline release rate. Intravenous injection of chlorisondamine (3 mg·kg–1) did not change the release of noradrenaline, while dopamine release was reduced.It is concluded that the release of catecholamines in the locus coeruleus is influenced by signals originating from peripheral baroreceptors. The influences are similar under pentobarbital and chloralose anaesthesia. Noradrenergic neurons responding to haemodynamic signals are not uniformly distributed within the locus coeruleus. It is suggested that noradrenergic and possibly dopaminergic and adrenergic neurons of the locus coeruleus are involved in the baroreceptor reflex, thus contributing to central homeostasis of blood pressure. 相似文献
16.
Bela Szabo Tobias Auberle Klaus Starke 《Naunyn-Schmiedeberg's archives of pharmacology》1993,348(3):249-257
Summary Inhibition of uptake, in the central nervous system leads to a decrease of sympathetic outflow to many tissues; central a2-adrenoceptors are involved in this decrease. The aim of the present study was to compare the effects of the selective uptake, inhibitor (+)-oxaprotiline on the plasma kinetics of noradrenaline and adrenaline in anaesthetized and in conscious rabbits. [3H]Noradrenaline and [3H]adrenaline were infused iv. The arterial plasma concentrations of endogenous and radiolabelled noradrenaline and adrenaline were measured, and the clearance from and spillover into the plasma of noradrenaline and adrenaline were calculated.Results obtained in conscious and anaesthetized rabbits were similar. (+)-Oxaprotiline 0.2, 0.6 and 1.8 mg kg–1 iv. dose-dependently reduced the clearance of [3H]noradrenaline from the plasma. The clearance of [3H]adrenaline was reduced less. The spillover of endogenous noradrenaline was decreased by up to 35%. In contrast, the spillover of adrenaline tended to be enhanced. Prazosin 0.1 and 1 mg kg–1 was injected iv. in a second part of each experiment. It lowered the blood pressure and caused a marked increase in noradrenaline spillover but no increase or even a decrease in adrenaline spillover.The results are compatible with the following hypothesis. The sympathetic outflow from the central nervous system is subject to a twofold a-adrenoceptor-mediated modulation: -adrenoceptor-mediated inhibition and 1-adrenoceptor-mediated excitation. In the control of the sympathetic outflow to many extra-adrenal tissues, the 2-adrenergic inhibition prevails. Uptake1 inhibitors depress sympathetic outflow to such tissues by enhancing the 2-adrenergic inhibition. In the regulation of the sympathetic outflow to the adrenal medulla, in contrast, 2-adrenergic inhibition and 1-adrenergic excitation have a similar impact. Uptake, inhibitors, hence, cause little change in adrenaline release: the two opposing influences cancel out. Prazosin produces an increase in noradrenaline but not adrenaline release because the loss of the central 1 sympathoexcitation attenuates at best slightly the baroreflex to most extra-adrenal tissues but dampens markedly the baroreflex to the adrenal medulla.
Correspondence to B. Szabo at the above address 相似文献
17.
M. C. Koss 《Naunyn-Schmiedeberg's archives of pharmacology》1980,314(2):135-139
Summary -Methyldopa (10–100 mg/kg i.v.) produced a dose-dependent pupillary dilation in anaesthetized cats which was antagonized by subsequent administration of yohimbine hydrochloride (0.5 mg/kg i.v.). The peak effects were observed approximately 2–3h after injection. This -methyldopa-induced mydriasis was present only when the parasympathetic innervation to the iris was intact. Prior treatment with yohimbine (0.5 mg/kg i.v.) 30 min before -methyldopa also antagonized the mydriatic effect, whereas pretreatment with phenoxybenzamine (2.5 mg/kg i.v.) did not. In contrast, phenoxybenzamine, but not yohimbine, effectively antagonized the pupillary dilation produced by adrenaline (0.3–10.0 g/kg i.v.). These results suggest that -methyldopa produces mydriasis in the cat by means of CNS inhibition of tonic outflow from the oculomotor nucleus and that an -adrenergic inhibitory mechanism may be involved. This conclusion is supported further by experiments in which direct measurements of ciliary nerve activity were made. 相似文献
18.
D. Athen H. Beckmann M. Ackenheil M. Markianos 《European archives of psychiatry and clinical neuroscience》1977,224(2):129-140
Summary In eight male patients with alcoholic delirium concentrations of 3-methoxy-4-hydroxyphenylglycol (MHPG) and homovannilic acid (HVA) in CSF, activity of dopamine--hydroxylase (DBH), and urinary excretion of noradrenaline (NA), adrenaline (A), and dopamine (DA) were measured during the delirium and a drug-free control period.MHPG concentration in CSF, excretion of NA and A as well as activity of serum DBH were significantly elevated during the delirium phase as compared to the control period. Urinary DA excretion and HVA in CSF did not show any constant changes. There was a positive correlation (r=0.64) between DBH activity and the intensity of the delirium (as measured on the delirium rating scale).It is hypothesized that there is a relationship between alcoholic delirium and increased central noradrenergic activity.Parts of this study were presented at the Sixth International Institute on the Prevention and treatment of Drug Dependence (Hamburg, June 28–July 2, 1976) 相似文献
19.
J S Cameron M S Gaide K Epstein H Gelband R J Myeburg A L Bassett 《Journal of molecular and cellular cardiology》1984,16(4):321-330
Right ventricular pressure overload of 3 days' duration was established in cats by banding of the pulmonary artery. To characterize the regional distribution of the resulting electrophysiologic changes, the right ventricular free wall, adjacent pulmonary outflow tract and septum were mounted in tissue bath and examined by conventional microelectrode techniques. Abnormal action potentials, identified by a negative shift of the voltage level of phase 2 with a corresponding accentuation of phase 1, were recorded from sites contiguous to the tricuspid valve and pulmonary outflow tract and in limited adjacent areas. No abnormal action potentials were recorded on the septal surface, apical end of the free wall, or at any right ventricular location in normal or sham-operated cats. Abnormal potentials could be recorded from sites sampled 5 cell layers deep in the endocardium. The number and extent of distribution of cells demonstrating altered action potentials correlated best with increased right ventricular wet weight at time of sacrifice. Abnormal cells responded to epinephrine or elevated extracellular calcium by a shift in plateau voltage towards zero and by an increase in action potential duration prior to usual plateau shortening. Responsiveness of these cells to agents which influence slow inward current suggests pressure overload-induced changes in the cell membrane that limit or otherwise affect availability of calcium. Regional distribution of plateau potential abnormalities may reflect differential physical stress within the myocardium provoked by sudden pressure overload. 相似文献
20.