bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Descending Control of the Lumbosacral Spinal Cord from the “Mesencephalic Locomotor Region”
Authors: Grillner S. , Shik M. L. 
Published: December 2008

AbstractContinuous stimulation (60 c/s) of a region below the inferior coliculus can induce locomotion on the treadmill of precollicular, postmammilar cats. This study aims at revealing what changes occur in the spinal cord, when the “locomotor region” is stimulated. This stimulation enables the cat to walk if the treadmill is moved. After controlling the threshold for evoking good locomotion, the cats were curarized. Stimulation at a strength that evoked walking prior to curarization induced a depression of inhibitory short‐latency reflex effects to α‐motoneurones from cutaneous, and high threshold muscular afferents without changing the direct excitability of α‐motoneurones. The threshold for evoking longlasting reciprocally organized discharges was lowered. The results suggest that the effects are induced by a slow fiber system, that releases the activity of the spinal stepping generating neurones. The results would be explained if the noradrenergic reticulospinal system was activated from the mesencephalic locomotor region.
Mucosal Lesions in the Small Intestine of the Cat during Low Flow
Authors: ÅHrén Christer , Haglund Ulf 
Published: December 2008

AbstractThe mucosal changes, produced at the villous tips of the cat small intestine during a mimicked shock situation (regional hypotension at 30 mm Hg during nervous vasoconstrictor fibre activation), were examined macro‐and microscopically. Macroscopically, petechial bleedings and ulcerations were regularly seen in the mucosa after a 2 h hypotensive period. The microscopic findings were characterized by epithelial lifting of various degrees at the tips of the villi and in some cases by a complete denudation of the villous tips. Intraluminal perfusion of a segment with oxygenated saline during the hypotension prevented or greatly reduced the mucosal lesions compared to control segments. On the other hand, intraluminal perfusion with nitrogenated saline did not change the mucosal lesions as compared with control. This strongly indicates that hypoxia per se plays an important role in the pathogenesis of the mucosal lesions, while the intestinal content (e.g. energy substrates or enzymes) does not appear to be of any great importance. It is suggested that the hypoxia is caused by an extravascular shunting of oxygen in the intestinal countercurrent exchanger.
Colonic Motility in the Cat
Authors: Rostad Hans 
Published: December 2008

AbstractRostad. H. Colonic motility in the cat. III. Influence of hypothalamic and mesencephalic stimulation. Acta physiol. scand. 1973. 89. 104–115.Colonic motility recorded with sensitive extraluminal strain gage transducers was studied in lightly anesthetized cats following electrical stimulation of hypothalamic, and mesencephalic structures. Stimulation of various structures of the hypothalamus produced the following: 1) The sympatho‐inhibitory area in the anterior hypothalamus increased colonic activity concomitantly with a fall in blood pressure. 2) The ventral anterior and lateral hypothalamus produced excitatory colonic effects, but these were usually associated with a rise in blood pressure. Similar effects were obtained from the dorsal part of the ventromedial hypothalamic nucleus. 3) Stimulation of the ventral part of the hypothalamus, mainly corresponding to the course of the medial forebrain bundle, and the ventral part of the ventromedial nucleus, resulted in inhibitory colonic effects. Stimulation of various structures of the mesencephalon produced the following: 1) The central gray substance, red nucleus and reticular substance elicited increased colonic effects, most conspicuous in the proximal part of the colon. These responses were usually associated with a blood pressure rise. 2) Points within the central tegmental tract and the medial lemniscus resulted in inhibition of colonic motility. The. functional significance of the results and their relation to behavioural patterns are discussed.
Glycogen Depletion Pattern in Human Muscle Fibres During Distance Running
Authors: Costill D. L. , Gollnick P. D. , Jansson E. D. , Saltin B. , Stein E. M. 
Published: December 2008

AbstractCostill, D. L., P. D. Gollnick, E. D. Jansson, B. Saltin and E. M. STEIN. Glycogen depletion pattern in human muscle fibres during distance running. Acta physiol. scand. 1973. 89. 374–383.Muscle biopsy and venous blood samples were taken from 9 subjects before and after a 30 km race. Additional measurements were made when 8 subjects ran 20.5 km of the course 2‐3 weeks later. Information about total metabolism and the glycogen depletion pattern in the fibres of the thigh muscle during prolonged running has been obtained from these measurements. The average oxygen uptake and respiratory exchange ratio were 4.7 1×min‐1 (83 % ot maximal oxygen uptake) and 0.90, respectively. An average intramuscular tryglyceride reduction of 2.2 mmoles×kg‐1 (30 %) accounted for only part of the lipid combusted. Muscle glycogen declined 56 % (from 98 to 42 mmoles of glucose units × kg‐1) during the race. Histochemical staining of the muscle for glycogen revealed a marked depletion in the slow twitch fibres. Only a small glycogen depletion occurred in the fast twitch fibres. This suggests a primary reliance upon slow twitch fibres during prolonged running. The results also point to the limitations of assessing substrate utilization or availability in working fibres from muscle samples with mixed fibre populations.
Rat Liver Glucokinase Activity Studied in Liver Perfusion System
Authors: Hoddevik G. , Spydevold Ø. 
Published: December 2008

AbstractAttempts were made to demonstrate an adaptive increase in glucokinase in isolated perfused livers. Several physiological factors, such as insulin, hydrocortisone, high glucose and low fatty acid concentrations, which may have a regulatory effect on the adaptive process in vivo were tested. None of these were sufficient to bring about the adaptation in vitro. Glucokinase of livers from fasted rats and then perfused with either bicarbonate buffer, 100 % blood or with mixtures of these media were studied. The concentration of free fatty acids in the media was decreased by addition of insulin and elevated by anti‐insulin serum. These changes were not accompanied by change in glucokinase activity. A moderate decrease in glucokinase in livers from carbohydrate fed rats was observed when the livers were perfused for several hours with subphysiological glucose concentration in the medium. The enzyme was quite stable, however, when glucagon was added to the system. The adaptive increase in glucokinase activity could be demonstrated if the fasted rats were refed a carbohydrate diet for 3 hours before the livers were excised. However, addition of insulin to the perfusion medium was not necessary. When the protein synthesis inhibitor cyclohemixide was added to the perfusion system, the glucokinase from carbohydrate fed liver was quite stable whereas the enzyme in standard diet fed rat livers decreased significantly within 6 hours from the start of the perfusion. This indicates a different turnover rate of the enzyme under different physiological conditions.
Urinary Excretion of Noradrenaline after Treatment with α‐Methyldopa: Inhibition by a Central Nervous Mechanism
Authors: Andén Nils‐Erik , Henning Matts 
Published: December 2008

AbstractNormal rats treated with L‐α‐methyldopa (400 mg/kg i.p.) after inhibition of the peripheral L‐DOPA decarboxylase by α‐methyldopa hydrazine excreted significantly less noradrenaline in the urine. The adrenaline excretion was only insignificantly reduced. The results indicate that treatment with a‐methyldopa can inhibit the release of noradrenaline from the sympathetic nerves by decreasing the impulse flow from the central nervous system. The adrenal medulla is influenced to a smaller degree.
An Autoradiographic Study of the Intestinal Absorption of 22Na
Authors: Jodal Mats 
Published: December 2008

AbstractThe distribution of 22Na within the villous tissue was studied by means if an autoradiographic technique during absorption of different saline solutions containing the tracer, the resolving power being about 10 μm. After the first minute of absorption most of the grains were localized in the epithelial cells, the grain density in the lamina propria being low. The same distribution of 22Na was seen after 5 min incubatlon during maximal vasodilatation and during absorption of a hypotonic saline solution. On the other hand, a constant intraluminal perfusion of isotonic saline for 30 min changed the autoradiographic picture, the highest radioactivity concentration now being found in the lamina propria. The gradient of grain density along the villous length was, however, not as marked as that reported by Haljamae et al. (1973), who proposed that this gradient was created by a countercurrent multiplication of sodium in the hairpin vascular loops in the villi. The results in this paper support the hypothesis that both sodium and water are crossdiffusing in such a system between the vessels constituting the countercurrent exchanger.
Carbonic Anhydrase in the Cornea
Authors: Lönnerholm Gudmar 
Published: December 2008

AbstractCarbonic anhydrase activity in the corneas of adult man, human fetus, monkey, rabbit, rat, cow, pig and American bullfrog was examined by the histochemical method of Hansson. In all species the endothelial cells were intensely and distinctly stained for carbonic anhydrase activity. The enzyme inhibitor acetazolamide at 10‐‐5M in the incubation medium completely, and at 10‐‐6M almost completely, inhibited the staining. There was no staining in other parts of the cornea with the possible exception of a few cells in the frog epithelium. Endothelium, epithelium and stroma of cow and rabbit corneas were dissected and homogenized. The carbonic anhydrase activity was determined by a changing pH, indicator method. Only the endothelium showed activity and this was sensitive to inhibition by acetazolamide.
Role of the α‐Receptor in the Control of Noradrenaline Release from Sympathetic Nerves
Authors: Hedqvist Per 
Published: December 2008

AbstractPhenoxybenzamine, hydergin and phentolamine, all markedly increased the overflow of 3H‐nor‐adrenaline in response to transmural stimulation of the guinea pig vas deferens. After phannacological blockade of neuronal and extraneuronal uptake of noradrenaline, and after inhibition of local prostaglandin formation, the three compounds were still effective and caused increased overflow of 3H‐noradrenaline. This effect was abolished by prostaglandin E2. Using the same pharmacological blockade, noradrenaline and methoxamine inhibited stimulated overflow of “H‐noradrenaline in a dose‐dependent manner. It is concluded that the activity of α‐receptors Per se can feed back regulate the release of noradrenaline from sympathetic nerves. The possibility that the receptors are presynaptically located and that they act on Ca++ influx into the neuron is discussed.
Stimulation of Lymphocyte Release from the Spleen by Theophylline and Isoproterenol
Authors: Ernström U. , Sandberg G. 
Published: December 2008

AbstractThe effect of theophylline and isoproterenol on the splenic release of lymphocytes into the blood was studied in guinea pigs by the comparison between the content of cells in splenic afferent and efferent blood, combined with determination of the blood flow through the spleen.An intracardial injection of theophylline, like that of isoproterenol, resulted in a greatly increased release of lymphocytes from the spleen as compared to that in control animals. The effect of theophylline, in contrast to that of isoproterenol, could not be abolished by pretreatment with propranolol. The similar effects of theophyliine (known to inhibit the degradation of cAMP) and isoproterenol (known to stimulate the synthesis of cAMP) on the splenic release of lymphocytes to the blood suggest that these effects may be mediated by an increase of intra‐cellular cAMP. This suggestion is supported by our finding of an additive effect when theophylline and isoproterenol were administered in combination.The abovementioned release of lymphocytes was found shortly after administration of the drugs. After isoproterenol it was followed by an inhibited release of lymphocytes from the spleen. This was in contrast to the much longer duration of the releasing effect of theophylline.
Trapping of Radioactive Microspheres in the Pregnant and Non‐Pregnant Rabbit
Authors: Greasy Robert K. , Kahanpää Kari V. , Swiet Michael de 
Published: December 2008

AbstractWe injected radioactive microspheres, 15, 25 and 50 μn in diameter in the left ventricle or the lower aorta of rabhits and counted the radioactivity in the lungs to estimate the fraction of microspheres shunted through the systemic circulation. The degree of microsphere shunting was inversely proportional to microsphere diameter. The maximum fraction of 15 μm micro‐spheres shunted after an aortic injection was 8.8 % as compared with 6.2 % with 25 μm spheres and 1.2 % with 50 μm spheres. There was no statistically significant change in the fraction of microspheres shunted in pregnancy or with anesthesia. Shunted microspheres may continue to arrive in the lungs for up to 15 min following aortic injection. Microspheres at least 25 μm in diameter should he employed to measure the fractional distribution of cardiac output in rahbits although it may he preferable to use smaller microspheres to measure blood flow within certain organs.
Observations on Closed Tissue Cultures of Sympathetic Ganglia of Chick Embryos in Media Buffered with N‐Tris‐(Hydroxymethyl) Methyl‐Glycine or N‐2‐Hydroxy‐Ethyl‐piperazine‐N‐2‐Ethanesulfonic Acid
Authors: Hervonen Heikki , Rechardt Leena 
Published: December 2008

AbstractA simple and practical closed tissue culture system for sympathetic ganglia is described. It has proved suitable in metabolic and pharmacological studies of sympathetic neurons, where it is necessary to maintain the neurons in good condition for longer periods. The effects of coverslip, Nerve Growth Factor (NGF) and various concentrations of glucose and serum on nerve fibre growth were estimated in N‐tris(hydroxymethyl)methyl‐glycine (TRICINE) or N‐2‐hydroxy‐ethylpiperazine‐N‐2‐ethanesulfonic acid (HEPES) buffered culture mediums. TRICINE and HEPES buffers were found non‐toxic to the nervous tissue and by these buffers it was possible to avoid CO2‐gassing and to use a closed environment, which facilitated daily checking of explants.Although the sympathicoblasts were not dissociated before culturing, a monolayer of the neurons with dense network of nerve fibres formed in this culture system. This pattern of growth made it possible to perform histochemical reactions (fluorescence microscopy and electron microscopical histochemical reactions) directly in the culture dishes.
Time Course for Refilling of Glycogen Stores in Human Muscle Fibres Following Exercise‐Induced Glycogen Depletion
Authors: Piehl Karin 
Published: December 2008

AbstractMuscle biopsy samples were obtained from the thigh muscle of 4 subjects before and after 2 h of work and at selected intervals during the following 46 h when a carbohydrate enriched diet was consumed. Mean glycogen content declined 103 (from 125 to 22) mmol glucose units × kg‐l following exercise. 5 and 10 h after consuming the carbohydrate enriched diet muscle glycogen increased to 64 and 86 mmol glucose units × kg‐l, respectively. During the first 5 h there was a marked storage of glycogen in the muscle which was related to the carbohydrate intake, but pre‐exercise concentrations of muscle glycogen were observed first after 46 h. The increase in glycogen occurred in both fibre types, but the fast twitch fibres replinished their glycogen somewhat faster than did the slow twitch fibres suggesting a higher glycogen synthetase activity. At glycogen concentrations above 80–90 mmol no differences in the glycogen content of the two fibre types could be discerned with histochemical methods.
Denervation Changes in Frog Skeletal Muscle
Authors: Nasledov G. A. , Thesleff S. 
Published: December 2008

AbstractThe effects of denervation on acetylcholine sensitivity and on the electrical properties of frog tonic and phasic muscle fibres were examined by the use of iontophoretic micro‐application of acetylcholine and conventional intracellular techniques for recording and stimulation. In tonic fibres extrajunctional cholinergic sensitivity appeared 4 days after sectioning of the nerve and by 2 weeks the entire membrane had attained a high level of acetylcholine sensitivity. The sensitivity of former end‐plate regions also increased with time. In phasic fibres cholinergic sensitivity appeared about one week later but otherwise followed the same pattern as in tonic fibres. Innervated tonic fibres are incapable of generating action potentials but this property is induced upon denervation. After one week of denervation small spikes were observed in response to depolarizing current pulses and by 2 weeks large action potentials, sometimes followed by repetitive discharges were recorded. Denervation failed to affect the action potential in phasic fibres. Tetrodotoxin completely blocked action potentials in tonic and in phasic fibres. Denervation reduced the effective resistance and the time constant of tonic fibres but had no effect on these properties in phasic fibres. Actinornycin D injected i.p. in a single dose (7.5 or 9.0 μg) failed to prevent the appearance of extrajunctional cholinergic receptors but almost completely blocked the induction of action potentials in denervated tonic fibres.
The Effects of Repetitive Stimulation on the Action Potential and the Twitch of Rat Muscle
Authors: Hanson Jerker 
Published: December 2008

AbstractMembrane potentials and contraction curves of different types of rat muscle fibre have been studied at body and room temperatures with special regard to the effects of repetitive stimulation. Fast fibres (from the surface of the extensor muscles of the antebrachium) have a higher resting membrane potential, a higher amplitude and shorter duration of the spike of the action potential and a larger early negative after‐potential than soleus fibres. In the fast fibres stimulation at 10 Hz for 30 s produced a decicase of the resting membrane potential, a decrease in the amplitude of the spike of the action potential and an increase in its duration, as well as an increase in the early negative after‐potential. In soleus fibres such changes were rare. These findings indicate that there are differences in the membrane properties between the two types of muscle fibres in addition to previously known differences in mechanical properties. Repetitive stimulation of fast fibres at body temperature caused a rapid increase in the twitch amplitude (staircase phenomenon). This increase occurred before any appreciable change in the action potential. Stimulation at room temperature caused only small changes in the twitch amplitude but marked increase in the twitch duration. This suggests that repetitive stimulation may alter both the amplitude and the duration of the active state curve.
Influence of Aldosterone on Active Sodium Transport by the Toad Bladder: a Kinetic Approach
Authors: Crabbé Jean 
Published: December 2008

AbstractSodium transport by the urinary bladder of the toad, Bufo marinus, was analysed by measuring the rate of transfer of radiosodium from the tissue towards the serosal compartment at steady state with respect to labelling from the rnucosal surface. Two sodium pools were identified of which only the fast‐disposal pool (with a half‐time of 1.7 min) reflected the sodium‐transporting activity of the preparation. When transepithelial sodium transport was stimulated by aldosterone, the half‐time of the fast‐disposal sodium pool was not modified. This is taken as additional evidence for the assumption that aldosterone does not influence the handling of sodium by the “pump”.
Sympathetic Vasodilatation, Kallikrein Release and Adrenergic Receptors in the Cat Submandibular Salivary Gland
Authors: Gautvik K. , Kriz M. , Lund‐Larsen K. , Waaler B. A. 
Published: December 2008

AbstractThe adrenergic receptors involved in secretion of kallikrein and the vasodilatation occurring subsequent to sympathetic nerve stimulation have been studied in the cat submandibular salivary gland. Measurements were made of kallikrein content in glandular homogenate and of venous outflow and glandular perfusion pressure. Isoprenaline failed to cause secretion of kallikrein in contrast to sympathetic nerve stimulation and close arterial injections of noradrenaline. Nerve stimulation and noradrenaline reduced the amount of kallikrein in the glands by 60 and 50 per cent, respectively. The α‐blocking agent Regitin® inhibited completely the secretion of kallikrein induced by nerve stimulation, while adrenergic β‐blockade had no inhibitory effect on enzyme secretion. In this gland, therefore, the secretion of kallikrein is mediated entirely through activation of adrenergic α‐receptors.The β‐blocking agent propranolol reduced the nerve induced vasodilatation by about 40 per cent. This sympathetic vasodilator response was present, but markedly reduced, after pretreatment with Regitin,® which abolished kallikrein secretion and the vasoconstrictor phase of the nerve‐induced vascular response. This study and an earlier report (Gautvik, Kriz and Lund‐Larsen 1972 a) suggest that β‐adrenergic receptors in the glandular vessels, as well as ®aL‐adrenergic receptors involved in the secretion of kallikrein, play a role in the vasodilatation observed in this gland subsequent to sympathetic nerve stimulation.
Glycogen Depletion Pattern in Muscle Fibres of Trotting Horses
Authors: Lindholm Arne , Bjerneld Håkan , Saltin Bengt 
Published: December 2008

AbstractFive trained standardbred horses were studied trotting at two speeds (300 and 500 m × min‐1) for 4 h and 1 h, respectively, and one horse at maximal speed. Their mean muscle glycogen content was reduced from 103 to 43 mmol × kg‐1 in the 1‐h experiment and from 119 to 48 mmol × kg‐1 in the 4‐h experiment. At maximal trotting speed, muscle glycogen declined from 88 to 46 mmol × kg‐1 in 3 aggregate min of exercise. Glycogen depletion patterns in slow twitch (ST), fast twitch, high oxidative (FTH) and fast twitch (FT) fibres were estimated on the basis of the periodic acid‐Schiff reaction. The ST and FTH fibres were depleted at all exercise intensities. These fibres then probably sustained almost all the exercise at slow trotting speeds as long as their glycogen stores were not depleted. After prolonged trotting and at high speeds, there appeared to be a progressive increase in FT fibre recruitment. Liver glycogen was reduced from 151 to 95 mmol × kg‐1 in the 1‐h run and from 116 to 19 mmol × kg‐1 in the 4‐h run, respectively. The fatigue found in horses trotting for long periods of time or at high speeds could be related to a selective depletion of glycogen in the ST and FTH fibres.
Des Mécanismes Biochimiques de 1'Automatisme Cardiaque. Examen de la Myxine
Authors: Rybak B. , Simon M. 
Published: December 2008

AbstractKinetic titrations of cAMP in the branchial heart of Myxitae glutitrosa seem to show that CAMP is involved in automatic processes and that there are quantitative differences in cAMP and specific phosphodiesterase inside the auricle and inside the ventricle in such a way that, compiling the present results with other data, one explains how the auricle is the dominant pacemaker in this heart.