bluuebunny/crossref_metadata_2025_split huggingface dataset:
Post‐Tetanic Decurarization in Developing Cat Leg Muscles
Authors: Nyström Bo 
Published: December 2008

AbstractThe effect of a conditioning tetanization on the twitch tension and size of compound muscle action potentials of subsequent twitches has been studied in partly curarized gastrocnemius and soleus muscles of kittens, ranging in age from 3–140 days, and adult cats. Nembutal® anesthesia was used. Comparisons were made with results obtained in non‐curarized animals.At all ages, a post‐tetanic increase in twitch tension in both muscles, when partly curarized. was accompanied by a similar increase in size of the muscle action potentials.In adult cats, high‐frequency tetanizations (250–450 d/sec) were more effective than low (45 c/sec) in eliciting the decurarizing effect. In young kittens, both were about equally effective.The effect of tetanization on the half relaxation time of post‐tetanic twitches was found to differ in normal and in partly curarized gastrocnemius muscles, whereas this did not apply to the soleus of young kittens.In both muscles, the post‐tetanic effects seen in non‐curarized and in partly curarized muscles differed with respect to the muscle action potential changes, as well as to the time course and frequency‐dependence of twitch potentiation. This indicates that the PTP of twitch tension found in normal muscles is, most probably, brought about mainly by a mechanism other than recruitment of muscle fibres.
The Relative Role of Recapture and of de novo Synthesis for the Maintenance of Neurotransmitter Homeostasis in Noradrenergic Nerves
Authors: Hedqvist P. , Stjärne L. 
Published: December 2008

AbstractExperiments were carried out in the isolated, perfused cat spleen to assess the capacity of the mechanisms of synthesis of noradrenaline to keep pace with the loss of noradrenaline by overflow from the organ, during prolonged periods of electrical nerve stimulation. The organ was pretrcated with the monoamine oxidase inhibiting drug nialamide to block deamination of noradrenaline. Phenoxybenzamine or cocaine+ Hydergin were added to the perfusion fluid in order to inhibit reuptake of noradrenaline liberated from the nerves, and to facilitate washout of noradrenaline in the extracellular fluid by preventing the vasoconstriction response.De novosynthesis of noradrenaline was found to proceed at a rate comparable to the highest values described in the literature. However, the discharge of noradrenaline from the neurons in response to nerve stimulation, as reflected by the peak overflow of noradrenaline from the organ, occurred at an approximately ten times higher rate. The results imply that the major mechanism for the maintenance of a constant noradrenaline level in the neuron from one moment to the next, during periods of increased nerve activity, is notde novosynthesis, but rather an almost quantitative reuptake of the noradrenaline liberated from the neurons.
Studies on the Histamine Releasing Effect of Bee Venom Fractions and Compound 48/80 on Skin and Lung Tissue of the Rat
Authors: Fredholm Bo , Haegermark ÖSten 
Published: December 2008

AbstractTwo bee venom fractions, F I and F II, obtained by gel filtration, and compound 48/80, were shown to release histamine from skin and lung tissue of the rat. F I is the phosphatidase A containing fraction, and F II contains a basic polypeptide. Dose‐response relationships, the time course of the histamine release, and the influence of enzyme inhibitors were studied. The results with F II and compound 48/80 were similar, suggesting that the two substances activate the same kind of release mechanism. It is concluded that F II is not related to the earlier described bee venom polypeptides melittin and aparnin. The mode of action of phosphatidase A was distinctly different from that of F II or compound 48/80. The results are consistent with the assumption that it acts in a “non‐specific.” way by hydrolysing tissue phosphatides to lyso compounds, which in turn damage the tissue.
Enzyme Activities at the Surface of Intact Human Erythrocytes
Authors: Ronouist Gunnar 
Published: December 2008

AbstractThe activity of glyceradehyde‐3‐phosphate dehydrogenase, phosphoglycerate kinase and adenylate kinase was determined at the surface of intact red cells, suspended in isotonic sodium chloride or isotonic sodium chloride containing 6 % Dextran. The surface‐bound phosphoglycerate kinase activity was found to be 4.5 %of the total phosphoglycerate kinase activity of the cell. The corresponding figures for glyceraldehyde‐3‐phosphate dehydrogenase and adenylate kinase were 3.1 % and 2.0 %, respectively. The extent of hemoglobin leakage into the assay medium did not exceed 1 % in any case. The suspending medium, after the cells had been removed, contained no glyceraldehyde‐3‐phosphate dehydrogenase or phosphoglycerate kinase activity, whereas part of the adenylate kinase activity had been eluted from the cells.
The Mechanism of Histamine Release from Isolated Rat Peritoneal Mast Cells Induced by d‐Tubocurarine
Authors: Frisk‐Holmberg Marianne , Uvnäs Börje 
Published: December 2008

AbstractIsolated rat peritoneal mast cells were exposed to d‐tubocurarine, and the release of histamine was studied under various conditions. The proposal is made that d‐tubocurarine although a monomer induces histamine release by a mechanism similar to that one triggered by the polymer synthetic amine compound 48/80.
The Effect of Menthol on Taste Receptors
Authors: Hellekant Göran 
Published: December 2008

AbstractThe response to menthol and its effect on the excitability of the gustatory receptors were studied by recording the impulse activity in the chorda tympani nerve of the cat. It was observed that menthol elicited a slowly increasing activity in all gustatory fibres. Adding menthol changed the gustatory response of the sapid solutions in two respects: a) It slightly suppressed the initial burst of activity, b) It enhanced the sustained response. Rinsing with menthol left the gustatory receptors with a changed sensitivity to stimulation with other sapid solutions. This effect on the receptors was related to concentration and length of the preceding menthol rinse. It showed also variations with regard to stimulus, concentration and subject.
The Evolution of Vascular Smooth Muscle Responses to Histamine and 5‐Hydroxytryptamine: II. Appearance of inhibitory actions of 5‐hydroxytryptamine in amphibians1
Authors: Reite Ola Bodvar 
Published: December 2008

AbstractSystematic studies on the vascular smooth muscle responses to histamine and 5‐hydroxytryptamine, similar to those previously accomplished in jawless vertebrates and fish, were performed in amphibians (frogs, toads and salamanders). Both intact animals and artificially perfused preparations were studied. The effects were recorded as changes in systemic arterial blood pressure after intravascular administration of drugs or as changes in vascular resistance after introduction of drugs into the perfusion fluid during perfusion at constant flow rate. Responses to adrenaline, noradrenaline and acetylcholine were studied for comparison. The direct or indirect nature of actions produced by the different drugs were evaluated by means of pharmacological blocking agents. The outcome of the studies may be summarized as follows: Marked and specific inhibitory actions of 5‐hydroxytryptamine on vascular smooth muscle, manifest as vasodilatation, are present in all studied species, displaying a feature which has not been demonstrated in jawless vertebrates and fish. In addition, the blood vessels of some amphibians occasionally show a constrictor response to 5‐hydroxytryptamine. The nature of the latter response remains uncertain. Histamine apparently has but negligible influence on amphibian vascular smooth muscle. The inhibitory and stimulatory actions of adrenaline and noradrenaline and the stimulatory action of acetylcholine, pharmacological characteristics of vascular smooth muscle also in more primitive vertebrates, are retained in the amphibians, while the inhibitory action of acetylcholine, like the inhibitory action of 5‐hydroxytryptamine, appears as a new feature.
Hemodynamics in the Bone Marrow of Anemic Rabbits with Increased Hematopoiesis
Authors: Michelsen Kåre 
Published: December 2008

AbstractIn fifteen rabbits heniatopoiesis was stimulated by a grave phenylhydrazine anemia. When the hematopoietic activity was maximal as judged from the reticulocyte counts, 6 or 7 days after the first injection of phenylhydrazine, the left femur was perfused in situ through the nutrient artery by blood led through an extracorporal perfusion arrangement from the left carotid artery of the anesthetized animal. The blood flow, the nutrient artery perfusion pressure and the intramedullary venous pressure were recorded. The bone marrow blood flow was greater and varied less than in non‐anemic animals. The arterial vessels exhibited a weak ability to auto‐regulate flow and acetylcholine caused arterial dilatation showing that neither the grave anemia nor the great hematopoietic activity had brought about a maximal dilatation of the arterial vessels. The venous resistance to bone marrow blood flow was constantly small whereas it has previously been shown to vary greatly in non‐anemic animals.
The Firing Pattern of Dorsal Spinocerebellar Tract Neurones during Inhibition
Authors: Jansen J. K. S. , Nicolaysen K. , Walløe L. 
Published: December 2008

AbstractDorsal spinocerebellar tract neurones adequately activated by Ia afferents from the tibialias anterior (TA), extensor digitorum longus (EDL) or flexor digitorum longus (FDL) muscles are regularly inhibited by group I afferents from the gastrocnemius‐soleus (GS) nerve. The inhibition is maintained throughout the duration of GS nerve stimulation. During inhibition the irregularity of firing may be unchanged or moderately reduced. Correspondingly the serial dependency between neighbouring intervals may be unchanged or reduced. The inhibitory input usually caused a constant reduction in firing frequency at various levels of excitatory drive or occasionally a greater reduction at higher levels of excitatory drive. The latter effect was associated with increased regularity of firing and reduced serial dependency. Comparable inhibitory effects were obtained by repetitive stimulation of the contralateral somato sensory‐cortex. It is suggested that the inhibitory effects can be accounted for by post‐synaptic inhibitory mechanisms.
Changes in the Cell Volume of Isolated Vascular Smooth Muscle in Response to Reduced Osmolarity
Authors: Jonsson Olof 
Published: December 2008

AbstractThe intracellular water of smooth muscle from the rat portal vein decreases on exposure to hyperosmotic solutions to an extent expected for perfect osmometers (Arvill, Johansson and Jonsson 1969). The purpose of the present study has been to investigate the variations in cell water produced by reductions in extracellular osmolarity.After 15 min of incubation at 37° C in a solution which was 105 mOsm/l hypo‐osmotic (minus 60 mmoles NaCl/1) compared to normal Krebs solution, the intracellular water increased by 14 ± 7 per cent in muscles stretched to their in situ length and by 35 ± 9 per cent in unstretched muscles. When the same procedures were performed at 1° C, a temperature that considerably reduced the mechanical response to hypo‐osmolarity, the volume of the cell water in the stretched and unstretched muscles increased to approximately the same extent (40 and 35 per cent respectively). These results suggest that the active tension development associated with excitation at low osmolarity opposed the swelling of the muscle cells in the stretched muscles at 37° C while the passive tension per se was less important for the degree of swelling. However, had the smooth muscle cells behaved like perfect osmometers the increase in cell water at this reduction in osmolarity would have been 58 per cent. The difference between this value and those obtained in situations where the active tension development was prevented might be accounted for by a loss of intracellular ions. Such a loss of ions was clearly demonstrated in stretched muscles at 37° C which showed the smallest degree of swelling. This suggests that muscle cells, when unable to adapt their intracellular osmolarity to a reduced extracellular tonicity by swelling, do so by dropping a fraction of their intracellular ions.
Hyperosmolality and Vasodilatation in Human Skeletal Muscle
Authors: Lundvall Jan , Mellander Stefan , White Thomas 
Published: December 2008

AbstractExercise of the forearm muscles in man was found to cause a considerable increase of the osmolality in the venous effluent but no osmolar change in arterial blood, thus indicating a regional hyperosmolality in the working muscles. There was a relation between the degree of hyperosmolality during work and the extent of the exercise hyperemia (determined immediately after cessation of exercise). Experimental hyperosmolality of similar magnitudes, produced in the resting skeletal muscle by intra‐arterial infusion of hypertonic solutions of glucose, xylose, or mannitol, invariably elicited a dilatation of the resistance vessels, whereas there was no significant effect of isotonic infusion. Vascular resistance tended to decrease progressively with increasing osmolality. Furthermore, intramuscular deposits of Xe133in the resting muscle were cleared more rapidly when the tracer was dissolved in hypertonic than in isotonic medium, indicating a hyperemia response also when the hyperosmolality primarily involved the extra‐vascular space. The results are discussed in relation to previous studies of the effects of hyperosmolality on skeletal muscle circulation in anesthetized animals and on vascular smooth musclein vitro.The conclusion was reached that hyperosmolality can be one factor contributing to exercise hyperemia in man.
The Effect of Acetazolamide upon Tissue Concentrations of Bicarbonate, Lactate, and Pyruvate in the Rat Brain
Authors: Kjällquist A. , Nardini M. , Siesjö B. K. 
Published: December 2008

AbstractThe effect of various doses of acetazolamide upon acid‐base parameters in brain tissue, cisternal CSF and arterial plasma was studied in rats, anesthetized with phenobarbital or nitrous oxide. The results confirmed older findings that carbonic anhydrase inhibition increases the CSF/plasma ratio for bicarbonate, and decreases the corresponding chloride ratio, and showed that the CSF pH remains unchanged during at least 6 hrs in spite of a marked plasma acidosis. The tissue bicarbonate was found to be significantly, but transiently, increased, and since the CSF bicarbonate was essentially unchanged, the increase in bicarbonate must have occurred in the intracellular phase,i.e.an alkaline shift in the cells. However, both the lactate and the pyruvate concentrations in the tissue were decreased after acetazolamide, suggesting an acidosis. It is discussed if these controversial findings indicate that caibonk anhydrase inhibition gives rise to a carbonic acid acidosis in the brain.
Effects of Some Metabolic Co‐Factors and Inhibitors on Transmitter Release and Uptake in Isolated Adrenergic Nerve Granules
Authors: Euler U. S. von , Lishajko F. 
Published: December 2008

AbstractVarious nucleotides and metabolic inhibitors have been tested on the release, reuptake and net uptake of noradrenaline (NA) in isolated splenic nerve granules. Cytidine, inosine, and uridine triphosphate facilitated uptake of NA to a similar degree as adenosine diphosphate but less than adenosine triphosphate. Cyclic AMP had no effect.Various inhibitors of the respiratory chain and oxidative phosphorylation (rotenone, chlorpromazine, antimycin and oligomycin) inhibited both release and uptake of NA at 10–3–10–4M. Atractylate had no action at 10–3M. Cyanide and azide at 10–3M had no or a slight action only.The uncouplers dinitrophenol, carbonyl cyanidem‐chlorophenyl hydrazone, desaspidin, and pentachlorphenol all increased the release rate of NA from granules and inhibited reuptake.The results suggest that the ATP facilitated uptake process requires electron transport and that the ability of the granules to retain bound NA is dependent on an energized state of the system. At least certain steps of electron transport‐coupled phosphorylation occurring in mitochondria appear to be involved in amine release and uptake in granules.
Effects of Slow Infusions of KCl into the 3rd Brain Ventricle
Authors: Olson Kerstin 
Published: December 2008

AbstractDuring slow (7.5 μl/min) infusions of strongly hypertonic (0.4–0.85 M) KCl solutions into the anterior part of the 3rd brain ventricle of the goat, a series of behavioural reactions developed (strong thirst and polypnea, later on accompanied by hyperphagia and minor rage reactions). Similar infusions of less hypertonic or isotonic KCl also induced thirst and polypnea but no hyperphagia. Natriuresis and a temporary inhibition of the water diuresis of hydrated animals were other effects elicited by the intraventricular infusions of both isotonic and hypertonic KCl. The effects of the KCl infusions on the water and electrolyte balance were compared to those obtained by similar infusions of equimolar NaCl in the same animal.It is concluded that a rather selective, non‐specific stimulation of diencephalic mechanisms may be obtained by slow infusions of KCl into the anterior part of the 3rd ventricle. The experiments have given no evidence that an elevated K+ concentration in the diencephalic region stimulates renal K+ excretion specifically.
Studies on the Relaxing Actions Mediated by Stimulation of Adrenergic α‐and β‐Receptors in Taenia Coli of the Rabbit and Guinea Pig
Authors: Son Rolf Anders , Mohme‐Lundholm Ella 
Published: December 2008

AbstractIn experiments on taenia coli from rabbits, a study was made of the mechanisms whereby catecholamines induce a relaxing effect. In a low concentration (≤2.1 × 10–6g/ml), l‐phenylephrine selectively stimulated adrenergic a‐receptors; this effect was blocked completely by the adrenergic α‐blocking agent dibenamine. In a low concentration (≤ 3.7 × 10–8g/ml), 1‐isoprenaline selectively stimulated β‐receptors; this effect was blocked completely by the adrenergic β‐receptor blocking agent sotalol. In higher concentrations, phenylephrine and isoprenaline stimulated both adrenergic α‐and β‐receptors; their relaxing effect could only be blocked completely by a combination of dibenamine and sotalol. In taenia coli from rabbits, the threshold concentration for β‐receptor‐mediated relaxation was lower than that for relaxation induced via a‐receptors; in taenia coli from guinea pigs the reverse was found. The relaxant effect induced via adrenergic a‐receptors was blocked selectively by factors such as cold treatment, digitalis glycosides, desoxycorticosterone, which could be assumed to decrease the ionic gradients of K+ and Na+ across the cell membrane or reduce its ionic permeability. — On successive reduction of the carbohydrate reserves of the muscle, the relaxation induced via adrenergic β‐receptors was inhibited more rapidly than that induced via α‐receptors. Theophylline and puromycin, which inhibit the enzymatic hydrolysis of cyclic AMP, potentiated selectively the β‐receptors mediated relaxation.
Effects of Gastric and Jejunal Juice Extracts on Gastric Acid Secretion
Authors: Semb Lars S. 
Published: December 2008

AbstractThe specificity of inhibition of i.v. injected extracts prepared from the gastric antral juice of dogs was studied by comparison with extracts prepared from canine fundic and jejunal pouches. The extracts were prepared by dialysis against water and lyophilization, and injected in doses of 1 mg/kg b.w. into Heidenhain pouch dogs secreting at a steady state from constantly infused histamine. Extracts of antral juice (22 expts. in 5 dogs) were found to inhibit gastric secretion in 17 expts. (average 63.6%), while in 4 expts. there was stimulation of gastric secretion (average 57%). Extracts of fundic juice were tested in 21 expts. in 4 dogs, and showed inhibition in 10 (average 50.4%) and stimulation in 10 expts. (average 54.8%). The extracts obtained from jejunal secretions were tested in 15 expts. on 3 dogs, and showed inhibition of gastric acid secretion in 9 expts. (average 50.6%), while in 4 expts. there was significant stimulation of the secretion (47.7%). Rectal temperature was increased more than 0.5° C in 8 of the experiments with antral juice extracts, in 4 with fundic extracts, and in 7 with jejunal extracts. Inhibition or stimulation was observed in these experiments. It is concluded that dialyzed and lyophilized extracts from gastrointestinal secretions contain substances that either stimulate or inhibit gastric secretion. The inhibitory effect could not be completely explained by pyrogenicity of extracts.
Structure and Function of the Tactile Hair Receptors on the Cat's Foreleg
Authors: Nilsson Bengt Y. 
Published: December 2008

AbstractThe cat's carpal sinus hairs are shown to be supplied by free nerve endings and Merkel cellneurite complexes. Using a mechanical stimulator permitting hair displacements at varying rates and amplitudes, dynamic and static responses were analyzed. Most units respond to static displacement by slowly adapting discharges which after an initial decline in frequency attain a steady state whose frequency is related to the displacement amplitude by a power function. The frequency in the dynamic phase rises with the rate of rise, increasing during the movement and decreasing as the final plateau is attained. The dynamic response is related to the rate of rise by a power function. Most of these slowly adapting receptors respond most effectively to proximal hair movements. Movement of one hair elicits responses in several units which may have reciprocal directional sensitivity. Each fiber supplies only one hair. Effects of pilomotor muscle activation on the afferent inflow were demonstrated in experiments concerning the possible existence of an efferent regulating mechanism. Above a minimum velocity some receptors discharged in the dynamic phase, being silent in the static phase. These rapidly adapting receptors responded to movements in all directions and displayed off responses. Fiber conduction velocities were determined.
Studies on Central Regulation of Secretion of Antidiuretic Hormone (ADH) in the Goat
Authors: Olsson Kerstin 
Published: December 2008

AbstractA further analysis was made of the antidiuretic response to infusions of NH4C1 into the 3rd brain ventricle of hydrated goats. The response was obtained in the absence of “osmotic” stimulation, but was evidently due to a release of antidiuretic hormone (ADH), since it disappeared after the induction of experimental diabetes insipidus. No antidiuresis was obtained by infusions of hypertonic saccharose into the 3rd ventricle. The activation of heat dissipation mechanisms by local warming of the preoptic/anterior hypothalamic region was not associated with any inhibition of the water diuresis. However, profound local cooling of this part of the brain induced a release of ADH in hydrated animals. The possibility is discussed, that this effect of local brain cooling may be due to a reduction of a neural inhibition, normally exerted on the ADH release.