bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in Motor Unit Activity and Metabolism in Human Skeletal Muscle during and after Repeated Eccentric and Concentric Contractions
Authors: Komi Paavo V. , Viitasalo Jukka T. 
Published: December 2008

AbstractThis study was designed to investigate electromyographic (EMG), muscle glycogen and blood lactate changes in quadriceps muscle group during repeated 40 maximal eccentric and concentric contractions, and to follow the recovery in EMG, muscle glycogen and serum creatine kinase values during a 4 day period following the work test. The subjects were normal males and the test order (eccentric or concentric) was randomly selected. The results indicated first, that the EMG parameters (IEMG, AMUP), muscle glycogen and blood lactate changed in a similar manner during the both fatigue loads. Despite the high tension work no selective depletion of glycogen could be observed in the slow or fast twitch muscle fibres in either type of work. The restoring of muscle glycogen occurred in a similar manner after the both fatigue loads, and no significant differences were present between eccentric and concentric works in the serum creatine kinase levels for a 2 days period. The eccentric work was associated with muscle soreness, which was strongest during the second day after the termination of the work test. The recovery of the EMG parameters were also delayed in eccentric fatigue. After concentric fatigue EMG‐activity returned to normal values within 2 days.
Cerebral Blood Flow and Oxygen Consumption in Rat, Measured with Microspheres or Xenon
Authors: Gjedde Albert , Monte S. M. De La , Caronna John J. 
Published: December 2008

AbstractThe cerebral blood flow and, in some rats, the cerebral rate of oxygen consumption were measured in three groups of male rats. Fractionation of radioisotope‐labeled microspheres was used to measure regional cerebral blood flow in four parts of the rat brain. The arterial and cerebral venous concentrations of radioactive xenon during desaturation were used to measure the blood flow and oxygen consumption of cortex when venous blood was collected from the superior sagittal sinus, or of whole brain when the transverse sinus was sampled. The regional cerebral blood flow measured with microspheres had a large standard error reflecting the technical difficulty of this method. The cerebral blood flow measured with xenon was higher when venous blood was sampled from the superior sagittal sinus than when sampled from the transverse sinus, but cerebral oxygen consumption rates were similar. The difference reflects the greater trauma involved in the superior sagittal approach and possible extracerebral contamination present in the transverse sinus approach.
Adenylate Cyclase Activity in Corpus Striatum of Rats with Porto‐Caval Anastomosis
Authors: Laursen H. , Klysner R. , Geisler A. 
Published: December 2008

AbstractAltered catecholamine receptor sites within the striatum have been proposed to be an important pathogenetic factor in hepatic and porto‐systemic encephalopathy and coma. The unstimulated, fluoride‐, norepinephrine‐ and dopamine‐stimulated adenylate cyclase activity were measured in the corpus striatum of rats with a four weeks old end‐to‐side porto‐caval anastomosis. There was no difference in unstimulated, fluoride‐ or hormone‐stimulated adenylate cyclase activity between porto‐caval shunted and sham‐operated rats. The in vitro dose‐response curves of norepinephrine and dopamine were similar in both groups of animals. Half‐maximum and maximum stimulation were achieved in shunted and sham‐operated rats by identical concentrations of norepinephrine and dopamine, respectively. The results indicate that neither changes in unstimulated adenylate cyclase activity nor changes in the response of adenylate cyclase activity to fluoride, norepinephrine and dopamine had developed in the rats at the stage studied.
Central and Regional Circulatory Effects of Adding Arm Exercise to Leg Exercise
Authors: Secher Niels H. , Clausen Jan P. , Klausen Klaus , Noer Ivan , Trap‐Jensen Jens 
Published: December 2008

Abstract7 young, healthy, male subjects performed exercise on bicycle ergometers in two 20 min periods with an interval of 1 h. The first 10 min of each 20 min period consisted of arm exercise (38–62% of Vdot;o2max for arm exercise) or leg exercise (58–78% of Vdot;o2max for leg exercise). During the last 10 min the subjects performed combined arm and leg exercise (71–83% of Vdot;o2max for this type of exercise). The following variables were measured during each type of exercise: oxygen uptake, heart rate, mean arterial blood pressure, cardiac output, leg blood flow (only during leg exercise and combined exercise), arterio‐venous concentration differences for O2and lactate at the levels of the axillary and the external iliac vessels.Superimposing a sufficiently strenuous arm exercise (oxygen uptake for arm exercise 40% of oxygen uptake for combined exercise) on leg exercise caused a reduction in blood flow and oxygen uptake in the exercising legs with unchanged mean arterial blood pressure. Superimposing leg exercise on arm exercise caused a decrease in mean arterial blood pressure and an increased axillary arterio‐venous oxygen difference. These findings indicate that the oxygen supply to one large group of exercising muscles may be limited by vasoconstriction or by a fall in arterial pressure, when another large group of muscles is exercising simultaneously.
On the Cation Exchanger Properties of Rat Mast Cell Granules and their Storage of Histamine
Authors: Uvnäs Börje , ÅBorg Carl‐Hugo 
Published: December 2008

AbstractMast cell granules free of a surrounding membrane were isolated from water‐lysed rat peritoneal and thoracic mast cells by differential centrifugation. The granules were depleted of their histamine by suspension in 10 mM sodium phosphate buffer and the sodium‐charged granules then converted into the “hydrogen form” by repeated washing in slightly acid deionized water. The cation exchanger properties of the mast cell granules were investigated by testing the applicability of the Rothmund‐Kornfeld equation for cation exchangers to the binding of Na+ and Hi+ ions to granule sites. The results lend further support to the view that the mast cell granule acts as a cation exchanger with the exchanger function localized to protein carboxyls in the protein‐heparin complex of the granule matrix.
Early Oestrogen‐Induced Changes in Uterine Albumin Exchange in Mice
Authors: Arvidson N. G. 
Published: December 2008

AbstractThe effect of the oestrogens, oestradiol and oestriol, on plasma albumin dynamics in the uterus was studied in mice. A double isotope technique with125I‐ and131I‐labelled human serum albumin was used. The optimum conditions to measure the extravascular accumulation of albumin were to use one labelled albumin as “permeability marker” (30 min circulation time) the other as plasma volume indicator (3 min circulation time). The oestrogens increased the extravascular accumulation of labelled albumin in the uterus but not in diaphragm or heart muscle. The accumulation was maximal after 4 h (75% higher than in controls) and was significant as early as 2 h after oestrogen administration. It cannot be decided whether the increase in labelled albumin accumulation was due to an increase in permeability and/or to an increase in the total surface area of perfused capillaries.
Oxygen Consumption and Contractile Force during Vibrations of Cat Soleus Muscle
Authors: Ljung Bengt , Hallbäck Margareta , Sivertsson Ramon , Folkow Björn 
Published: December 2008

AbstractThe influence of longitudinal vibrations (50 Hz, 0.4 mm) on isometric twitch force development (4 Hz), blood flow and oxygen consumption was studied in the acutely denervated soleus muscle of the anesthetized cat. It was found that the sinusoidal vibrations reduced the twitch amplitude by 60 per cent whereas oxygen consumption and blood flow were lowered by 15 per cent only. Similar reduction in twitch force was also obtained by lowering the nerve stimulation intensity (4 Hz). This was associated with a diminution in oxygen consumption, the degree of which was linearly related to the attenuation of active force, i.e. the number of activated motor units. The results are in agreement with previous observations as to the mechanical effect of vibrations on active force in smooth and striated muscle. They demonstrate that vibrations prevent the contractile response with maintained high oxygen consumption which adds further support to the hypothesis forwarded by Joyce et at. (1969) that vibrations cause increased rate of detachment of actin‐myosin crosslinks. In addition it appears possible that vibrations to some extent prevent formation of such cross‐links.
Transcapillary Exchange of14C‐Inulin by Free Diffusion in Channels of Fused Vesicles
Authors: Paaske William P. , Sejrsen Per 
Published: December 2008

AbstractCapillary permeability for the extracellular, hydrophilic indicator,14C‐inulin, was determined in the autoperfused cat gastrocnemius muscle by bolus injection, venous sampling expts. The capillary diffusion capacity, CDC (the permeability‐surface are product, PS), was 0.84 ml/100 g·min, and capillary extraction, E, was 0.307 at a plasma flow of 4.0 ml/100 g·min as average values of 7 expts. Results were compared with51Cr‐EDTA and57Co‐B12 data of previous studies. The findings imply that14C‐inulin is not subject to restricted diffusion across the continuous capillary membranes of skeletal muscle as compared to51Cr‐EDTA as well as57Co‐B12. These hydrophilic indicators pass the capillary barrier at rates proportional to their respective free diffusion coefficients in water. The Pappenheimer equivalent pore radius estimate of 30 Å (or slit width of 37 Å) and the Karnovsky 40 Å interendothelial slit width are inconsistent with the present data which imply a much larger pore size. The transendothelial channel system of fused vesicles is a possible morphological equivalent for the present findings which support the general theory that capillaries of continuous type exhibit similar permeation characteristics regardless of the tissue in which they are located. By kinetic black‐box analysis the extravascular distribution volume for14C‐inulin in skeletal muscle was found to be 13.0 ml/100 g. The data indicate that51Cr‐EDTA, which has about the same molecular radius as sucrose, and14C‐inulin have identical extravascular volumes of distribution and that both molecules presumably enter the sarcoplasmic reticulum.
A Simple Radioenzymatic Procedure for the Determination of Choline and Acetylcholine in Brain Regions of Rats Sacrificed by Microwave Irradiation
Authors: Eckernäs S.‐Ä. , Aquilonius S.‐M. 
Published: December 2008

AbstractA rapid and sensitive radioenzymatic method for analysis of choline (Ch) and acetylcholine (ACh) concentrations in rat brain regions is described. The ACh content is obtained as the difference in Ch concentration between a hydrolysed and an unhydrolysed tissue sample. The ACh content was 16 ± 1.0 nmol/g in the cortex and 76 ± 2.4 nmol/g in the striatum, and the corresponding Ch values were 23 ± 2.5 and 33 ± 1.2.
Monoaminergic Fluorescence in Frog Skin
Authors: Sjöberg Eva 
Published: December 2008

AbstractThe Falck‐Hillarp fluorescence technique was employed in an attempt to determine the distribution of sympathetic innervation in frog skin. No evidence was found of a direct monoaminergic nerve supply to the cells of the non‐glandular epithelium in the epidermis. Instead, specific fluorescence was mainly confined to the vicinity of the skin glands. Fluorescent fibers were observed surrounding the mucous type of gland. The secretory content of this gland was not fluorescent. In the granular type of gland the main source of fluorescence was the secretory granules filling the lumen. These developed a fluorescence in the spectral range of 5‐hydroxytryptamine. The brightness of the fluorescence indicated a very high content of this amine. Fluorimetric analysis showed that no catecholamines were present in the secretion. In glands devoid of secretory granules there were some indications of a monoaminergic innervation of the secretory epithelium, but this was hard to determine because of the abundant nonspecific fluorescence. Sparse dots of specific fluorescence were found close to the surrounding smooth muscle cells. — These findings rule out the possibility of a direct sympathetic nervous control of the non‐glandular epithelium in frog skin but indicate that this is instead confined to the skin glands.
In Vivo Studies of Individual Mucous Glands in the Frog
Authors: Skoglund C. R. , Sjöberg E. 
Published: December 2008

AbstractIndividual mucous glands in the toe web were studied in curarized decerebrate frogs using vital microscopy in combination with still or motion photomicrography. By changing the focus position to different levels various structures in the gland could be identified and their changes during glandular activation studied. The first visible effect of nerve stimulation was a contraction of the myoepithelium and probably also structural changes of the secretory epithelium resulting in a narrowing of the glandular lumen. Following this, the tricuspid valve opened and secretion was ejected. The latency and time course of the contractile response to nerve stimulation were determined and the influence of the number of stimuli on the duration of the contraction and relaxation phases was analyzed. Comparisons were made with reflex activation of the gland as well as with neurohormonal stimulation. The myoepithelial contraction was found to be under adrenergic control. Of the smooth‐muscle stimulants tested only Substance P induced contractions. The time course of the ionic outflow from the toe web was determined by conductance measurements in the fluid surrounding the web and compared with the visually observed phenomena. The initial outflow was concomitant with the phasic myoepithelial contraction but a continued secretion could also be observed and recorded from glands kept in a steady state of contraction by iterative nerve stimulation. The functions of the toe web glands were found to be critically dependent on a maintained circulation in the surrounding capillary network.
The Effect of Indomethacin on Renal Blood Flow Distribution during Hemorrhagic Hypotension in Dog
Authors: Tyssebotn I. , Kirkebø A. 
Published: December 2008

AbstractThe effect of indomethacin in hemorrhagic hypotension (HH) on total renal blood flow (RBF) and cortical flow distribution was studied in 9 pentobarbital anesthesized dogs. Local blood flow was measured as hydrogen clearance by 6 platinum electrodes in outer and inner cortex. RBF was recorded by electromagnetic flowmeter. Injection of indomethacin (3–5 mg/kg b.wt.) to inhibit prostaglandin synthesis, reduced renal blood flow only a few percent in control period. After the pretreatment with indomethacin, bleeding to mean arterial pressure 50 mmHg decreased RBF abruptly to 25% of control flow. Thus a renal vasoconstriction is observed both in early and late periods of bleeding in contrast to the initial vasodilation observed during the first half an hour of HH when prostaglandin formation was not blocked. Local blood flow in outer cortex decreased proportionally to flow in inner cortex during bleeding in both the indomethacin treated as in the untreated group, indicating an equal vasodilatory effect of prostaglandin in all parts of renal cortex during early periods of HH.
Effects of Ethanol on Urinary Arginine Vasopressin Excretion in Two Rat Strains Selected for Their Different Ethanol Preferences
Authors: Linkola Jaakko , Fyhrquist Frej , Forsander Olof 
Published: December 2008

AbstractThe effects of ethanol on urinary excretion of arginine vasopressin (AVP), sodium, and potassium were investigated in two rat strains specially selected for their different alcohol preferences. The alcohol preferring (AA) strain excreted more AVP and the water preferring (ANA) strain more urine and sodium during six hours after ethanol intubation (2.4 g/kg b.w.; 20% v/v). The data is insufficient to establish a causal relationship between differences in water and electrolyte metabolism and voluntary ethanol consumption.
The Interrelation between Hypothalamically Induced Changes in Sympathetic Discharge to the Gastrointestinal and Cardiovascular Systems
Authors: Delbro Dick , Lisander Björn 
Published: December 2008

AbstractIn chloralose‐anesthetized, adrenalectomized cats, the sympathetically conveyed effects of topical hypothalamic stimulations on gastric volume, blood pressure and heart rate were systematically explored. The vagal nerves were cut but could be kept active by graded efferent stimulation. In the absence of such vagal activity, hypothalamic stimulation had no appreciable influence on gastric volume, even though the stomach maintained considerable myogenic tone. When, however, a vagal excitatory activity was present, hypothalamic stimulation could markedly affect gastric tone, indicating that the sympathetic fibres exert their inhibitory influence on the stomach via its cholinergic intramural neurons. Hypothalamic stimulations that induced reductions in pressure or heart rate also usually caused an enhancement of gastric tone. Similarly, pressor responses were associated with decreases in gastric volume whereas stimulation‐induced tachycardia was not linked to any particular type of gastric response. Thus, the hypothalamic sympathoinhibitory influences on the cardiovascular system seem closely connected to a suppression of the sympathetic outflow to the stomach. There is, on the other hand, no regular association between hypothalamic sympatho‐excitatory influences on the cardiovascular and gastrointestinal systems; in fact, there is in many areas even a suppression of sympathetic discharge to the stomach in association with cardiovascular stimulation.
Fever and Behavioural Temperature Regulation in the FrogRana esculenta
Authors: Myhre Kjell , Cabanac Michel , Myhre Grete 
Published: December 2008

AbstractThe skin and colonic temperatures were recorded in frogs(Rana esculenta)which had selected a suitable microenvironment in a box filled with 2–3 cm water. The water temperatures ranged from 0°C to + 40°C. Such measurements were performed before and after intraperitoneal injections of killed pathogenic bacteria (M. xenopiandM. ranae), killed non‐pathogenic bacteria (M. aquae II) and 0.9% sterile saline, intraperitoneal injections of blood plasma from frogs pre‐injected with killedM. ranae, injections of PGE, into the brain. The injections of pathogenic bacterial endotoxin caused, after latencies of 5–120 min, higher preferred water temperatures, which produced an average maximum colonic temperature increase of 6.5°C ± 1.0°C (S.E.) (p< 0.001). The non‐pathogenic bacteria and sterile saline caused no temperature change. Monophasic hyperthermia of shorter latency was caused by injections of blood plasma from frogs pre‐injected withM. ranae.Monophasic hyperthermia of the shortest latency was observed after diencephalic injections of PGE1. Based on their similarity we suggest that ectothermic and endothermic fever have a common phylogenetic origin.
Postischemic Cerebral Blood Flow and Oxygen Utilization Rate in Rats Anesthetized with Nitrous Oxide or Phenobarbital
Authors: Nordström Carl‐Henrik , Rehncrona Stig 
Published: December 2008

AbstractThe present experiments were undertaken to measure postischemic regional cerebral blood flow (rCBF) and oxygen utilization rate (CMRo2) in rats anesthetized with either 70 % N2O or phenobarbital (150 mg × kg‐1). In previous studies we have found that extensive restitution of cerebral energy metabolites occurs after 30 min of complete cerebral ischemia irrespective of the type of anesthesia used. Following 30 min of pronounced, incomplete ischemia, however, a comparable restitution of cerebral energy state was obtained in deeply anesthetized (phenobarbital 150 mg × kg‐1) but not in superficially anesthetized (70% N2O) rats. The objectives of the present investigation were (1) to study whether postischemic cerebral blood flow was higher in barbiturate‐anesthetized animals during the initial recirculation period, and (2) to investigate if the protective effects of phenobarbital previously observed could be attributed to a decrease in CMRo2. In both groups of animals a considerable variability in postischemic rCBF was observed between different animals. However, no signs of gross inhomogeneity in blood flow were found and no consistent differences in flow values between the two groups of animals were observed. Since the measured postischemic CMRo, were identical in both groups of animals and since cerebral venous oxygen contents were above normal the results leave little support to the assumption that, in the present model of transient, incomplete cerebral ischemia, failure of recovery of cerebral metabolism (N2O group) is primarily due to impaired recirculation, nor do they indicate that the protective effects of barbiturates is due to their ability to reduce rate of cerebral energy utilization.
Protein Concentration in Interstitial and Lymphatic Fluids from the Subcutaneous Tissue
Authors: Rutili Gianfranco , Arfors Karl‐E. 
Published: December 2008

AbstractThe protein content of interstitial fluid and lymph from the same tissue was determined, fluid samples of nanolitre volumes being taken from the subcutaneous tissue of rabbits by micropuncture. In the same area lymph was collected from lymphatic vessels of 30–100 μm. An electrophoretic technique in poly‐acrylamide gels in glass capillaries was used for the analysis of proteins. The gels were stained and then scanned on a microscope equipped with a moving table and photomultiplier. The area under each protein band was calculated from the recorded densitograms. The method required only a few nanolitres of fluid for analysis. Using solutions of known protein concentrations the relationship between the amount of protein and the area under the densitogram band was investigated. This relationship was found to be linear, making it possible to quantify the protein content of both interstitial fluid and lymph samples. The interstitial fluid/plasma concentration ratios for albumin, transferrin, globulins and total proteins were 0.42, 0.42, 0.32 and 0.37. The albumin/globulin ratio in interstitial fluid was found to be 1.60 of the plasma value although the values obtained for lymph were similar to those found for interstitial fluid. The similarity between the protein concentration of interstitial fluid and lymph indicated that the endothelial lining of the terminal lymphatics did not restrict the passage of macromolecules into the lymphatics.