Noradrenaline content in the heart and spleen of the mouse under normal conditions and after administration of some drugs

Methamphetamine increases force of contraction in isolated human atrial preparations through the release of noradrenaline

We measured the cardiac contractile effects of the sympathomimetic amphetamine-like drug methamphetamine alone and in the presence of cocaine or propranolol in human atrial preparations. For a more comprehensive analysis, we also examined the effects of methamphetamine in preparations from the left and right atria of mice and, for comparison, analyzed the cardiac effects of amphetamine itself. In human atrial preparations, methamphetamine and amphetamine increased the contractile force, the relaxation rate, and the rate of tension development, and shortened the time to maximum tension and the time to relaxation. Likewise, in mice preparations, methamphetamine and amphetamine increased the contractile force in the left atrium and increased the beating rate in the right atrium. The effect in human atrial preparations started at 1µM, therefore methamphetamine was less effective and potent than isoproterenol in increasing contractile force. These positive inotropic effects of methamphetamine were greatly attenuated by 10µM cocaine and abolished by 10µM propranolol. The inotropic effects of methamphetamine in human atrial preparations were associated with, and are believed to be mediated at least in part by, an increase in the phosphorylation state of the inhibitory subunit of troponin. In conclusion, the sympathomimetic central stimulant drug methamphetamine (as well as amphetamine) increased contractile force and protein phosphorylation, presumably through a release of noradrenaline in isolated human atrial preparations. Thus, methamphetamine acts as an indirect sympathomimetic in the human atrium.

Modeling and imaging cardiac sympathetic neurodegeneration in Parkinson's disease

Parkinson's disease (PD) is currently recognized as a multisystem disorder affecting several components of the central and peripheral nervous system. This new understanding of PD helps explain the complexity of the patients' symptoms while challenges researchers to identify new diagnostic and therapeutic strategies. Cardiac neurodegeneration and dysautonomia affect PD patients and are associated with orthostatic hypotension, fatigue, and abnormal control of electrical heart activity. They can seriously impact daily life of PD patients, as these symptoms do not respond to classical anti-parkinsonian medications and can be worsened by them. New diagnostic tools and therapies aiming to prevent cardiac neurodegeneration and dysautonomia are needed. In this manuscript we critically review the relationship between the cardiovascular and nervous system in normal and PD conditions, current animal models of cardiac dysautonomia and the application of molecular imaging methods to visualize cardiac neurodegeneration. Our goal is to highlight current progress in the development of tools to understand cardiac neurodegeneration and dysautonomia and monitor the effects of novel therapies aiming for global neuroprotection.

Iontophoretic release of adrenaline, noradrenaline and 5-hydroxytryptamine from micropipettes

Estimations have been made of the amounts of adrenaline, noradrenaline and 5-hydroxytryptamine released by iontophoresis from micropipettes. In most experiments, the amount released was linearly related to the total electrical charge, but the transport numbers for different pipettes, filled with samples of the same solutions of adrenaline or of noradrenaline, varied substantially. Two pipettes containing noradrenaline failed to release any appreciable amounts of the drug. The transport number of 5-hydroxytryptamine was relatively constant (mean, 0.14).

THE SUBCELLULAR LOCALIZATION OF DOPAMINE AND ACETYLCHOLINE IN THE DOG CAUDATE NUCLEUS

The distribution of dopamine (3,4-dihydroxyphenylethylamine) between the subcellular fractions from homogenates of dog caudate nucleus was compared with the distributions of acetylcholine, 5-hydroxytryptamine and lactate dehydrogenase activity. The distributions of noradrenaline and 5-hydroxytryptamine between the subcellular fractions from homogenates of dog hypothalamus were also determined. Most of the dopamine, in contrast to acetylcholine, occurred in the soluble supernatant fraction; the remainder was associated with the fractions rich in pinched-off nerve ending particles, but localization in any one fraction was not as sharp as that of acetylcholine. Evidence is presented that suggests that the dopamine occurs in a free or easily released form throughout cell cytoplasm.

Adrenal catecholamine secretion during stimulation of the nasal mucous membrane in the rabbit

1. Left adrenal venous blood was collected in anaesthetized rabbits and analysed for catecholamine content by either a fluorimetric technique or a bio-assay method using the blood pressure of the pithed rat.2. Stimulation of the nasal mucous membrane with ether vapour or water caused apnoea, bradycardia, a rise in arterial blood pressure and an increase in adrenal medullary catecholamine secretion.3. During the pre-stimulation control periods adrenaline constituted 66% of the total catecholamine present in adrenal venous blood and noradrenaline 34%. These proportions altered during stimulation of the nasal mucous membrane to 72 and 28% respectively. Electrical stimulation of the left splanchnic nerve produced a secretion composed almost entirely of adrenaline.4. The increased catecholamine output elicited during stimulation of the nose occurred in animals whose pulmonary ventilation was maintained constant by means of a pump. It was abolished, however, by local anaesthesia of the nasal passages or by surgical division of the left splanchnic nerve.5. The increased secretion of catecholamines is therefore reflex in nature, and evidence is presented that it is the result of a primary reflex from the nose.

Effect of tetrabenazine and alpha-methyl-m-tyrosine on exploratory activity and brain catecholamines in rats

1. Spontaneous exploratory locomotor activity of Wistar rats was measured in photocell activity cages, and brain noradrenaline (NA) and dopamine (DA) were determined fluorometrically after ion exchange purification.2. Tetrabenazine (TBZ) (10 mg/kg) produced a fall in NA and DA concentrations in rat brain stems which was correlated with the fall in activity in female Wistar rats.3. alpha-Methyl-m-tyrosine (alphaMMT) reduced the concentration of rat brain NA without affecting DA concentration or activity.4. Pretreatment with alphaMMT did not stop TBZ from producing a marked reduction in activity and NA concentration, but partially protected DA from the depleting action of TBZ.5. These results support a role for catecholamines in the control of motor activity, but they do not implicate NA more than DA and they emphasize that the mechanism by which drugs affect the concentrations of catecholamines may be more important than the gross concentrations attained.

Monoamines and their metabolites in the avian brain

1. In the avian brain, a high concentration of dopamine was found in a sharply contoured region of the nucleus basalis which may or may not have included the nucleus entopeduncularis, and therefore lay within the palaeostriatum of the nomenclature of Crosby and Huber. This was thus the only region which may be considered biochemically homologous to the mammalian corpus striatum. For purposes of macroscopic identification only, the region is described here as the ;anterior part of the nucleus basalis'. The concentration of dopamine was 3 mug/g in the pigeon, about the same in the duck and chicken, and 7.5 mug/g in the finch. In the pigeon this region also contained some noradrenaline; the quantity of 5-hydroxytryptamine (1.4 mug/g) and 5-hydroxyindolylacetic acid (0.6 mug/g) was larger than in any other part of the brain.2. In the brain of the pigeon and the chicken, the highest concentrations of noradrenaline (1.5 and 1.4 mug/g) were found in the hypothalamus.3. The concentration of adrenaline was higher in the avian than in the mammalian brain. In the hypothalamus, it ranged from 0.4 mug/g in the pigeon to 1 mug/g in the chicken.4. Fluorescence microscopy, using the formaldehyde condensation method, showed, in the anterior part of the nucleus basalis, a large area of diffuse green-yellow fluorescence, similar in appearance to the fluorescence of the striatum of the rat. In addition this part of the brain contained a small region of fluorescent fibres and varicosities. It is suggested that the diffuse fluorescence was produced by dopamine. It was absent from brains of reserpine-treated pigeons.5. In the pigeon, reserpine, tetrabenazine and prenylamine produced a decrease in the concentration of brain monoamines, an effect which was comparable to that seen in mammals. Yet, none of these drugs raised the concentration of homovanillic acid, but they increased that of 5-hydroxyindolylacetic acid; these drugs raise the concentration of both acids in mammalian brain.6. In the pigeon beta-tetrahydronaphthylamine decreased the concentration of all monoamines and their metabolites, an action quite different from that produced in the mammalian brain.7. The main effect of morphine and of M 99 (6,14-endoetheno-7-(2-hydroxy-2-pentyl)-tetrahydro-oripavine hydrochloride) was a lowering of the noradrenaline concentration.8. As in mammals, chlorpromazine affected only the dopamine metabolism.9. In the guinea-pig and the pigeon, the administration of alpha-methyl-DOPA led to a substitution of much of the cerebral noradrenaline by alpha-methyl-noradrenaline, sometimes in excess of the lost noradrenaline. However, although the loss of dopamine was severe in both pigeon and guinea-pig, only little alpha-methyl-dopamine accumulated in the pigeon brain, so that it did not consitute a replacement for the lost dopamine; in the guinea-pig, alpha-methyl-dopamine was found in quantities similar to, or exceeding those, of the lost dopamine.