bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Nerve Activity on the Depletion of the Adrenergic Transmitter by Inhibitors of Noradrenaline Synthesis1
Authors: Corrodi H. , Malmfors T. 
Published: December 2008

AbstractWhen rats and mice are treated with an inhibitor of noradrenaline (NA) synthesis (H 44/68, the methylester hydrochloride of dl‐α‐methyltyrosine) there is a reduction in the NA content in sympathetically innervated organs such as the heart and the submandibular glands. In the present investigation the mechanism behind this depletion has been examined by biochemical methods and with the histochemical fluorescence method of Falck and Hillarp. If the nerve impulse flow in the adrenergic nerves is reduced to a minimum by cutting the preganglionic trunk, the decrease in the transmitter content is reduced both in the iris and the submandibular gland. This shows that the nerve impulse flow in intact nerves is the main cause of the depletion of NA after treatment with an inhibitor of NA synthesis. When mice and rats are exposed to cold (3°C) after treatment with H 44/68 there is a significantly greater reduction in the NA content of the heart than when the animals are kept at room temperature (22°C) after the same treatment. This indicates that there is an increased nerve impulse flow in the adrenergic nerves of the heart in the animals exposed to cold stress. Uptake of adrenaline in the heart may also indicate an increase in activity in the adrenal medulla of these animals. There is good correlation between the biochemical and histochemical findings but the latter indicate that there is a greater reduction in the adrenergic nerves of the iris than in the nerves of the submandibular gland.The investigation shows that inhibitors of NA synthesis are very useful in functional studies of the adrenergic nerves.
Effect of Cervical Sympathetic Stimulation on Accommodation in Monkeys An example of a beta‐adrenergic, inhibitory effect
Authors: Törnqvist Goran 
Published: December 2008

AbstractThe preganglionic cervical sympathetic nerve, of mainly cynomolgus monkeys (Macaca irus), has been stimulated electrically using different stimulation rates. The accommodative response to stimulation was a change in refraction towards hypermetropia. This response could not be inhibited by adrenergic α‐receptor antagonists, though these drugs reduced the blood volume changes in the eye upon stimulation. On the other hand, the β‐adrenergic blocker propranolol caused a complete elimination of the sympathetic stimulation response, though changes in eye volume seemed uninfluenced. The accommodative response (in diopters) to stimulation increased considerably when the eye was under strong cholinergic tone. When the animal was pretreated with a large dose of atropine. cervical sympathetic stimulation did not affect the refractive state of eye. The results indicate the presence of a β‐adrenergic, inhibitory mechanism of the ciliary muscle. Possibly this mechanism is responsible for distance accommodation (decrease in accommodation). Changes in vascular structures upon sympathetic stimulation play no practical part in regulating the accommodation.
The Effect of DOPA on the Spinal Cord. 1. Influence on Transmission from Primary Aflerents
Authors: Andén N.‐E. , Jukes M. G. M. , Lundberg A. , Vyklicky L. 
Published: December 2008

AbstractIn unanesthetized spinal cats an i.v. injection of DOPA depresses transmission of short latency effects from the flexor reflex afferents (FRA), including transmission of excitatory and inhibitory action to motoneurones and ascending pathways as well as transmission to primary afferent terminals. The depression resembles that of the decerebrate preparation. After DOPA the flexor reflex evoked by natural stimulation of the skin is increased. This increase is due to a long latency, long lasting discharge in flexor motoneurones evoked by repetitive activity in the FRA. The late discharge is accompanied by a late wave of depolarization in the dorsal roots. These events are due to long lasting activity in the spinal cord and do not depend upon a peripheral loop. The selective action of DOPA shows that its action on transmission in the spinal cord is not secondary to circulatory changes. The working hypothesis is forwarded that DOPA inhibits transmission of short latency effects from the FRA through liberation of transmitter from a descending noradrenergic pathway.
The Effect of DOPA on the Spinal Cord. 2.APharmacological Analysis
Authors: Andén N.‐E. , Jukes M. G. M. , Lundberg A. 
Published: December 2008

AbstractDrugs known to influence noradrenergic transmission were investigated with respect to their action on the effect of DOPA on transmission in the spinal cord. The effect of DOPA may be prevented by inhibition of DOPA decarboxylase and by pretreatment with reserpine, it is enhanced by inhibition of monoamine oxidase and reversed by the adrenergic α‐receptor blockers phenoxy‐benzamine and chlorpromazine; the β‐receptor blocker nethalide does not reverse it. The effect of DOPA is reduced in the chronic spinal preparation. These data show that DOPA acts by liberation of catecholamines (dopamine or noradrenaline) in the spinal cord. It is suggested that DOPA increases the synthesis and liberation of transmitter from the terminals of a descending noradrenergic pathway.
The Effect of Imipramine and Related Antidepressive Drugs on Estrus Behaviour in Ovariectomised Rats Activated by Progesterone, Reserpine or Tetrabenazine in Combination with Estrogen
Authors: Meyerson Bengt J. 
Published: December 2008

AbstractThe effects of antidepressive drugs were studied on estrus behaviour activated in ovariectomised rats by progesterone, tetrabenazine or reserpine in combination with estrogen. On tetrabenazine‐ activated estrus behaviour an inhibitory effect was obtained by imipramine, desmethylimipramine, amitriptyline and nortriptyline, but not by trimeprimine. All the mentioned antidepressive compounds reduced the progesterone activated heat response; however, trimeprimine and nortriptyline were effective only when comparatively high doses were used and furthermore the effect was short‐lasting. Reserpine‐activated estrus behaviour was inhibited by imipramine; other drugs were not tested. Imipramine and the monoamine oxidase inhibitors pargyline and nialamide acted synergistically in inhibiting progesterone‐activated estrus behaviour. There was no relation between the inhibitory effect on tetrabenazine activated estrus behaviour and the ability of the different antidepressant drugs to prevent tetrabenazine induced sedation or to induce hyperactivity (compulsive exploring behaviour). The present data further support the earlier suggestion that there exist serotoninergic pathways mediating inhibition of estrus behaviour. It seems that the antidepressive compounds studied potentiate central serotoninergic mechanisms.
Release of3H‐Metaraminol by Different Mechanisms1
Authors: Carlsson Arvid , Waldeck Bertil 
Published: December 2008

AbstractMice were given3H‐metaraminol i.v. After 15 min, when the uptake by the adrenergic nerve fibres had been almost completed, various drugs were given and their ability to release the amine was investigated. Protriptyline and chlorprothixene, which block the amine‐concentrating mechanism at the level of the cell membrane, caused a clearcut release of3H‐metaraminol. This was true also of reserpine and prenylamine, which block the amine‐storage mechanism of the granules. Combination of the two types of agents caused a much more rapid release than either type alone. Guanethidine appeared to possess both types of action. After pretreatment with reserpine3H‐metaraminol could still be taken up but was rapidly released by desipramine, which blocks the concentrating mechanism at the level of the cell membrane, and by analogues of the adrenergic transmitter,e.g.tyramine, metaraminol, and amphetamine. Monoamine‐oxidase inhibitors were found to release3H‐metaraminol. It is suggested that this release is mediated by monoamines accumulating in the adrenergic nerve fibers.
Studies on the Mechanism for the Calorigenic Effect of Adrenaline in Man
Authors: Svedmyr Nils 
Published: December 2008

AbstractAdrenaline infusion in man increased the oxygen consumption and the lactate, FFA and glucose concentrations in the blood. When the FFA‐mobilizing effect of adrenaline was blocked selectively with nicotinic acid the calorigenic effect was reduced by 29%. When L(+)lactate was infused in such a dose that the blood lactate concentration rose to the same level as after the adrenaline infusion, the oxygen consumption increased, this increase being 35% of the total increase induced by the adrenaline infusion. An increase in both lactate and FFA metabolism is therefore assumed to be of importance for the calorigenic effect of adrenaline in man. The possibility that adrenaline stimulates both a lactate and a FFA cycle is discussed. The importance of other mechanisms for the calorigenic effect such as the heart‐stimulating and hyperglycemic effects of adrenaline is also considered.
Glucose Uptake in Potassium‐Depolarized Mammalian Muscle
Authors: Crone Christian 
Published: December 2008

AbstractExperiments were performed on perfused cat hind limbs to study whether the uptake of glucose by striated muscle is linked with active transport of ions. The glucose uptake in the control periods was 1.4 μmole/100 g/min. Elevation of the plasma potassium concentration to 25–40 meq/l led to an average glucose uptake of 3.0 μmoles/100 g/min. Addition of strophanthin to a final concentration of 10‐5M strongly depressed glucose uptake, the average value being 0.3 μmole/100 g/min. The oxygen consumption in the strophanthin experiments fell from 7.3 μmoles/100 g/min to 6.9 μmoles/100 g/min. A Na/O‐ratio of 5 was calculated for mammalian muscle. Substitution with potassium‐rich blood after addition of strophanthin eliminated the strophanthin effect on glucose uptake. It is proposed that the mechanism for carrier‐mediated glucose uptake in mammalian muscle may be connected with the mechanism for active transport of either sodium or potassium.
The Effect of Calcium on Potassium Contractures of Single Slow Muscle Fibres of Xenopus Laevis
Authors: Lännergren Jan 
Published: December 2008

AbstractIsolated slow muscle fibresof Xenopus laeviswere subjectcd to step increases in external potassium concentration at various external calcium concentrations. An increase in [Ca]oshifted the curve relating peak tension to log [K]oto higher K‐koncentrations. a decrease in [Ca]ocaused a shift in the opposite direction. Similar effects were seen on the relation between inactivation and log [K]o+. The peak tension was but little affected by [Ca]o; the time‐course of contractures was altered in such a way that the rate of relaxation was increased in low [Ca]oand decreased in high [Ca]o. Evidence was obtained that the effect of altered [Ca]ooccurs as rapidly as that of altered [K]o. Some observations were also made on contractures in Ca‐free solutions and in solutions with Na partially subatituted bv Ba.
Static and Dynamic Properties of Golgi Tendon Organs in the Anterior Tibial and Soleus Muscles of the Cat
Authors: Alnæs Egil 
Published: December 2008

AbstractThe responses of tendon organs of the anterior tibial muscle have been studied during twitch contraction, passive stretch, fused tetanic contractions and sinusoidal stretching in Nembutal anesthetized cats. The majority of the tendon organs had similar thresholds to active contraction and passive stretch tension. Some tendon organs were found to discharge spontaneously in the relaxed muscle. An approximate power function relationship has been found between steady state impulse frequency and muscle tension. The receptor properties are compared with those of soleus tendon organs. It is concluded that static and dynamic properties of Golgi tendon organs in the anterior tibial and the soleus muscles fall within the same range of variation, and that apparent discharge dissimilarities can be explained as due to differences in muscle mechanics.
Renal Clearances and Urinary Sodium and Potassium Excretion during Supine Exercise in Normal Subjects
Authors: Castenfors Jan 
Published: December 2008

AbstractClearance of inulin (Cin) and para‐aminohippuric acid(cpah). free water clearance(ch2o)and urinary excretion of sodium and potassium during exercise were studied in 14 healthy male subjects. The exercise was performed on a bicycle ergometer (mean load 729 kpm/mini in the supine position. Cpahdecreased significantly, but Cinwas not significantly changed. The antidiuresis during and after exercise was principally secondary to decreased Ch2o, indicating ADH release. The urinary sodium excretion and per cent filtrered sodium exereted were significantly decreased during exercise, indicating increased tubular reabsorption of sodium. The findings suggest that the increased tubular reabsorption may in part be due to increased aldosterone excretion during exercise. Urinary potassium excretion was not significantly changed during exercise.
The Interaction of Secretin and Pancreozymin on the External Pancreatic Secretion in Dogs
Authors: Henriksen F. W. , Worning H. 
Published: December 2008

AbstractThe pancreatic secretion of fluid, bicarbonate and protein in 4 dogs with chronic Thomas type fistulae, has been studied in response to secretin (1U/kg b.w.), pancreozymin (1U/kg b.w.) and combined secretin‐pancreozymin (1U/kg b.w. of each). The secretion rates of fluid, bicarbonate and protein after combined, submaximal stimulation were highly reproducible, as indicated by the coefficients of variation 1.7 per cent (fluid), 3.9 per cent (bicarbonate) and 5.1 per cent (protein). The secretion rates of fluid and bicarbonate obtained after the combined stimulation with secretin‐pancreozymin (1U/kg b.w. of each) were very close to those obtained after isolated stimulation with maximal doses of secretin. Secretin and pancreozymin are shown to have a potentiating effect on the pancreatic secretion of bicarbonate, but only an additive effect on the secretion of protein.
Quantitative in Vitro Studies on Noradrenaline Uptake and its Inhibition by Amphetamine, Desipramine and Chlorpromazine
Authors: Häggendal Jan , Hamberger Bertil 
Published: December 2008

AbstractThe accumulation of noradrenaline (NA) was determined biochemically after incubation with NA of slices from the vas deferens, cerebral cortex and neostriatum of rats pretreated with reserpine and nialamide. It was found that both areas rich in NA terminals, such as the vas deferens and cerebral cortex, and areas rich in dopamine (DA) terminals, such as the neostriatum, efficiently accumulated NA. (+)‐Amphetamine effectively inhibited NA accumulation in all the tissues, whereas desipramine inhibited the uptake in areas rich in NA terminals efficiently, but in areas rich in DA terminals only to a slight extent. In this respect, the effect of chlorpromazine was similar to that of desipramine. The data strongly support the view that the reserpine‐resistant accumulation mechanism of the transmitter differs in the two types of catecholamine terminals.
Effects of “Diving” on Cardiac Output in Ducks
Authors: Folkow B. , Nilsson N. J. , Yonce L. R. 
Published: December 2008

AbstractArterial and central venous pressures (AP and CVP), cardiac output (CO) and heart rate (HR) were recorded, and stroke volume (SV) computed, in awake ducks before, during and after submersion, special attention being paid to the time course and extent of the induced changes. During rest CO was 1509 ml/min (S.D. 245), HR 244/min (S.D. 83) and SV 6.6 ml (S.D. 1.6). Immediately upon submersion CO and HR fell slightly and then showed a more gradual, up to twenty fold reduction within 1–2 min; SV decreased moderately despite a 10–20 mm Hg increase in CVP. During the immediate 1–2 sec postdive period HR increased to 300–500/min, with a sharp rise in AP while CVP fell. Within 10–15 sec a profound vasodilatation was established, AP and CVP returning towards normal. CO now reached 2500–4000 ml/min and SV increased beyond resting level. Thus, at the shift from submersion to emersion CO could increase up to fiftyfold within 10–15 sec; CO then returned towards control in 6–8 min. Results with vagal and sympathetic blocking agents suggest the following neurogenic events: During submersion inhibited sympathetic activity to the heart is coupled with a greatly intensified vagal discharge. reducing also ventricular contractility; the sympathetic vasoconstrictor fibre discharge is sharply increased. On emersion a complete reversal of this intense and differentiated pattern takes place within 1–2 sec. The receptors and central mechansims involved are briefly discussed.
Response Characteristics of Muscle Spindle Endings at Constant Length to Variations in Fusimotor Activation
Authors: Andersson Bengt F. , Lennerstrand Gunnar , Thoden Uwe 
Published: December 2008

AbstractThe aim of the present investigation was to determine the transfer function between fusimotor stimulus rate and afferent impulse frequency of muscle spindles at constant length. Spindle endings in the external intercostal and in the ankle extensor and flexor muscles of the cat have been subjected to variations in fusimotor stimulation frequency. The variations had sinusoidal form and ranged in repetition rate from 1/4 to 1/12 c/s. Both single‐fibre and double‐fibre stimulations were studied. Linear static and dynamic input‐output relations were found in the stimulus frequency range 60 to 180 pulses/sec. For all combinations of one or two fusimotor fibres to one spindle ending the transfer function had the same general form. The static sensitivities were largest for primary endings under static fusimotor control; about the same sensitivities were obtained in dynamic fusimotor activation of primary endings and in static activation of secondary endings. With regard to dynamic properties all combinations of fusimotor fibres and spindle endings were equivalent. This was further tested with step and triangular wave inputs. Explanations for this similarity are discussed.
5‐Hydroxytryptamine Release from Enterochromaffin Granules in vitro
Authors: Penttilä A. , Saris N.‐E. 
Published: December 2008

Abstract5‐Hydroxytryptamine (5‐HT) releasein vetrofrom cow and pig enterochromaffin granule preparations was studied. An accelerated 5‐HT release from the granule fraction was caused by: elevation of temperature, freezing and thawing, dilution, increase of the pH of the incubation medium, addition of chlorprornazine, irniprarnine, mepyramine, segontin®, tyramine, trypsin, hydrocorti‐sone and cortisone. In various isotonic salt and buffer solutions the amine release was faster than that in isotonic sucrose solution. A slight 5‐HT release was induced by Ca++ions, Titriplex III®, Titriplex IV® and histamine, and an almost complete release by CuCl2, distilled water and all the detergents studied. Monoamine oxidase inhibitors (in 0.15 M phosphate buffer, pH 6.9) and MgCl2(in 0.3 M sucrose solutions, pH 6.9) were the only chemicals that retarded amine release. The following chemicals had no effect: ACTH, thyroxine, adrenaline, noradrenaline, dihydroxy‐phenylalanine, tryptophan, indoleacetic acid, 3‐hydroxytyramine, acetylcholine or butyrylcholine with eserine, and guanethidine.The release of 5‐HT from enterochromaffin granules resembles in some ways amine release from platelets, mast cells or granules carrying norepinephrine but differs in others. The special features of the enterochromaffin granules are discussed.
Biliary Bile Acids and Hepatic Ultra‐Structure in Hamsters Fed Gallstone‐inducing and ‐dissolving Diets
Authors: Bergman F. , Linden W. van der , Sjövall J. 
Published: December 2008

AbstractBile acids in gallbladder and fistula bile and the hepatic structure were studied in hamsters fed gallstone inducing diets with and without supplementation of cholestyramine or thyroxine. The predominant bile acids identified were cholic, chenodeoxycholic, deoxycholic, 7‐keto‐deoxycholic and 7α, 12α‐dihydroxy‐3‐keto‐5β‐cholanoic acids. Small amounts of 7‐ketolitho‐cholic, 12‐ketolithocholic, 12α‐hydroxy‐3‐keto‐5β‐cholanoic, allocholic and (tentatively) urso‐deoxycholic acids were also found. The mean of the chenodeoxycholic/cholic acid ratios in hamsters fed a diet favouring the formation of cholesterol gallstones was 0.88 and fell to about 0.04 when 3 % cholestyramine was added to the diet. Thyroxine caused a similar but less striking fall of this ratio. The bile acid/cholesterol ratio was lower in animals on the cholesterol stone inducing diet and was increased by cholestyramine administration, which prevented the formation of cholesterol stones. As in previous work, morpho‐histochemical changes were found in the hepatic parenchymal cells almost exclusively of hamsters treated with the thyroxine containing diet which induces predominantly pigmented stones. Electron microscopy showed the cells to contain numerous lipid droplets and clusters of autophagic vacuoles. Possible relationships between biliary bile acids, cholesterol and gallstone formation and the effects of cholestyramine and thyroxine are discussed.
The Influence of Hypoxia on the Spontaneous Thalamic and Cortical Barbiturate Spindles
Authors: Etholm B. , Junge K. , Sveen O. 
Published: December 2008

AbstractSpontaneous barbiturate spindles in the thalamus and the cortex were recorded in cats anesthetized with barbiturates and subjected to hypoxia. During stagnant hypoxia produced by pharmacological reduction of the blood pressure, there was no spindle activity when the blood pressure was below 60 mm Hg. In hypoxic hypoxia, the spindles disappeared after the oxygen content of the nitrogen‐oxygen mixture had been reduced to 4.5 per cent. In this condition, the blood pressure was always at or above 80 mm Hg and very often above 100 mm Hg. The lack of spindles was probably the result of the combined effect of changes in the blood pressure and the local tissue oxygen level.—Before and after the state of no spindle activity, there was a period of high synchrony characterized by low degree of activity between the spindles and high‐voltage waves within the spindles. Except for the abrupt disappearance and reappearance of the spindles, the degree of synchrony was the only parameter of barbiturate spindle activity that varied during hypoxia.—The results suggest that the mechanism of spindle activity may operate with a relatively small number of cells. A more complex neuronal system with a greater number of synapses may be supposed to be more susceptible to severe degrees of hypoxia.
Inhibitory Action of Adrenergic Blocking Agents on Reuptake and Net Uptake of Noradrenaline in Nerve Granules
Authors: Euler U. S. von , Lishajko F. 
Published: December 2008

AbstractThe effect of various adrenergic blocking agents on the reuptake and net uptake of noradrenaline (NA) in isolated adrenergic nerve granules has been studied. All of the α‐ and β‐blockers tested exerted an inhibitory action on the spontaneous release rate of NA from granules and also on the reuptake of3H‐labelled NA from a medium containing 1–3×10‐6M NA. The highest activity was shown by the α‐blockers dihydroergotamine and Plegicil, but some β‐blockers were almost as active. No significant difference in inhibitory action was observed between the l‐ and d‐isomers of propranolol and Aptin. In the presence of ATP and NA 5 × 10‐6M‐10‐4M, the net uptake of NA in partially depleted granules was strongly inhibited by the same blocking agents as were most active on the reuptake. The present results confirm the previous finding that adrenergic blocking agents, both of the α and β‐type, inhibit NA uptake in nerve granules. The possible mediation of transmitter release and uptake by granule receptors is discussed.