bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Disappearance of Xe133 and I125 from Skeletal Muscle of the Anesthetized Dog during Sympathetic Cholinergic Vasodilatation
Authors: Bolme Per , Edwall Lennart 
Published: December 2008

AbstractThe disappearance rate of I125 and Xe133 from a depot in the gastrocnemius muscle of the dog was determined during vasodilatation caused by activation of the sympathetic cholinergic vasodilator nerves. During vasodilatation the disappearance rate of I125 and Xe133 increased. No systematic difference in the disappearance rate was observed between the water‐soluble (I125) and the fat‐soluble (Xe133) tracer. The vasodilatation did not usually last far more than 30 sec, and during this period the increase in disappearance rate often exceeded the increase in blood flow. The disappearance rate of Xe133 was studied from different muscles during stimulation of hypothalamic vasodilator pathways and was found to be enhanced from the splenius, latissimus dorsi and gastrocnemius muscles but not from the maeseter muscle.Vasodilator nerve stimulation and acetylcholine infusion caused comparable increases in disappearance rate during the blood flow increase. When the blood flow was back to resting levcls, a decrease in disappearance rate below control values was seen. The increase in disappearance rate during sympathetic nervous vasodilatation was usually less than during metabolic vasodilatation and after metabolic vasodilatation no decrease was observed in the disappearance rate. The results support the hypothesis that during metabolic vasodilatation precapillary sphincters are opened up leading to an increased capillary surface area while the vasodilator nerves do not directly influence the exchange surface area.
Effect of Physical Training on Circulation during Prolonged Severe Exercise1
Authors: Ekblom Björn 
Published: December 2008

AbstractBefore, and after 22 weeks of physical training, oxygen uptake, heart rate and cardiac output (dye dilution technique) were measured in 7 male subjects (22 to 26 years old) during pro longed severe exercise (60 min on 75 % of the individual's maximal oxygen uptake) and during exhausting work loads of about 5 min duration. Maximal oxygen uptake increased from 3.41 l/min (48.0 mllkg per min) before to 3.64 I/min (52.0 ml/kg per min) after the training (p<0.05). Maximal heart rate decreased from 201 beats/min before to 194 beats/min after the training (p<0.05). During the 1 hr work period after the training the stroke volume and mean blood pressure became higher (p<0.05) and (a—v)O2 diff. lower (p<0.05) than before the training. From the 5th to the 60th min of the prolonged work the heart rate increased about 20 beatslmin before as well as after the training.
The Evolution of Vascular Smooth Muscle Responses to Histamine and 5‐Hydroxytryptamine
Authors: Reite Ola Bodvar 
Published: December 2008

AbstractStudies on the vascular smooth muscle responses to histamine and 5‐hydroxytryptamine and on the distribution of these amines in different tissues were performed in several species of reptiles. The responses to adrenaline, noradrenaline and acetylcholine were studied for comparison. Vascular actions were recorded both in vivo as changes in systemic arterial blood pressure and in vitro as changes in vascular resistance in perfused preparations. The specificity of the action of each drug was evaluated by means of pharmacological blocking agents. Tissue levels of histamine and 5‐hydroxytryptamine were determined spectrofluorometrically. Fluorescence microscopy was used for histochemical localization of the histamine stores. The results indicate that histamine and 5‐hydroxytryptamine exert dual actions (inhibitory and stimulatory) on reptilian vascular smooth muscles which have thus acquired response patterns towards these amines similar to those found in mammals. Inhibitory as well as stimulatory actions of adrena line, noradrenaline and acetylcholine are also present in reptiles. Levels of 5‐hydroxytrypt amine are apparently low in most tissues, whereas many species show very high tissue levels of histamine. Histamine, except that of the stomach, is mainly located in tissue mast cells and blood basophils. Nutritional‐dependent variations in mast cell number are parallelled by varia tions in tissue histamine content. By comparing the present results with those previously ob tained in jawless vertebrates, fish and amphibians, a general outline of the evolution of vascular actions and tissue stores of histamine and 5‐hydroxytryptamine is presented.
The Metabolism of Nicotine and Cotinine by a Mouse Liver Preparation
Authors: Stålhandske Torbjörn 
Published: December 2008

AbstractThe metabolism of nicotine and cotinine by a 10,000 ×g supernatant fraction of mouse liver homogenate has been studied by using 14C‐labelled compounds. The metabolism of nicotine was found to be TPNH and O2 dependent and chromatographical evidences for the formation of cotinine, γ‐(3‐pyridy 1)‐γ‐oxo‐N‐methylbutyramide and hydroxycotinine are presented. Three unidentified metabolites and 14CO2 were also observed. The observed metabolites were also excreted in urine after intraperitoneal administration of nicotine. Chromatographical evidences revealed that cotinine is metabolized to hydroxycotinine, γ‐(3‐pyridyl)‐γ‐oxo‐N‐methylbutyr‐amide and/or demethylcotinine and one unidentified metabolite. No formation of 14O2 was observed.
Unit Responses in the Cochlear Nucleus of the Rat to Noise and Tones
Authors: Møller Aage R. 
Published: December 2008

AbstractThe spectral integration of single units in the rat's cochlear nucleus has been investigated by two different methods, namely1. by measuring the difference in sensitivity to broad band noise and to pure tones of a frequency equal to the unit's characteristic frequency (CF).2. by estimating the width of the tuning curve.The results show that the mean value of the width of the tuning curves increases with the CF of the units. The bandwidth at 3 dB above maximum sensitivity agrees with the mean value of the bandwidth estimated on the basis of the difference in threshold of tones and noise. Bandwidth values estimated on the basis of noise measurements 10 dB above the threshold, however, are smaller than those obtained on the basis of threshold values. The results thus indicate that the spectral resolution of single units in the rat cochlear nucleus above threshold is higher for broad band noise than the measurements with pure tones indicate (tuning curves). The time patterns of the neural responses to noise and tone stimulation, judged from a dot display of the discharges, show no apparent difference except for units with a very low CF.
Slowly Adapting Muscle Receptors in Man
Authors: Vallbo A˚. B. 
Published: December 2008

AbstractUnitary nerve impulses originating from slowly adapting muscle receptors were recorded with percutaneously inserted tungsten electrodes from the median and the tibial nerves in awake human subjects. Discharges from 72 receptors located in the wrist flexor muscles and the ankle extensor muscles were analysed. The possibilities to derive criteria of muscle spindles and Golgi tendon organs were tested by means of a number of experimental procedures. A differentiation between these two types of receptors could, for technical reasons, not be achieved by electrically induced muscle twitches. For the majority of the endings muscle spindle characteristics could be demonstrated. In relaxed muscles, a number of the muscle spindle afferents exhibited a high dynamic sensitivity to passive joint movements whereas a smaller proportion of them had a low dynamic sensitivity. A steady state discharge as a function of the muscle length could be demonstrated for some of them. During weak voluntary contractions without external muscle shortening, the majority of the units responded with a sustained impulse discharge which started and stopped almost simultaneously with the onset and the cessation of the extrafusal contractions. It was concluded that the motor cortex exerts a very powerful control of the intrafusal muscle fibres of the majority of the muscle spindles. For a few units the relation between the muscle force and the impulse frequency was very striking but for the majority of them this relation was poor. It was concluded that the former units were Golgi tendon organs.
Water Permeability in Rat Distal Tubules
Authors: Persson E. 
Published: December 2008

AbstractOsmotic and diffusional water permeability was studied in rat distal tubules in antidiuresis and water diuresis with a microperfusion technique. In antidiuresis the osmotic water permeability was 6.1 ± 1.2. 10‐‐8 em3 cm‐2 sec‐1 (cm H2O)‐l and the diffusional water permeability 327 ± 132 10‐‐5 cm/sec. In water diuresis obtained by hypophysectomy and water loading the osmotic water permeability was 1.6±1.6 10‐‐8 cm3 cm‐2 sec‐1 (cmH2O)‐1 and the diffusional water permeability was 157±32 10‐‐5 cm/sec, both values being significantly lower than in antidiuresis. The osmotic water permeability is much larger than the diffusional water permeability; this can only be partly accounted for by the existence of an unstirred layer and is supporting evidence for the concept of aqueous pores, through which the water moves down osmotic gradients mainly as bulk flow and not as a purely diffusional flow. The comparatively larger increase in osmotic water permeability than in diffusional water permeability in antidiuresis suggests that ADH can change the pore area‐pore diameter relation so that the bulk flow increase is larger than the diffusional water flow increase.
The Time Course of the Active State in Relation to Sarcomere Length and Movement Studied in Single Skeletal Muscle Fibres of the Frog
Authors: Edman K. A. P. , Kiessling A. 
Published: December 2008

AbstractThe rising and falling phases of the active state were analyzed, by means of quick‐release technique, during a series of 4 incompletely fused isometric twitches in single semitendinosus muscle fibres of the frog. The analysis was carried out at different sarcomere lengths within the range 1.7–2.8 μ. The rate of rise of the active state was independent of the sarcomere length. A reduction in fibre length was associated with an earlier onset of the decay of the active state leading to a decrease in duration of the activity at the shorter length. The duration of the active state at 1.9 μ sarcomere spacing was 69 (range: 51–40) per cent of the duration existing at 2.6 μ sarcomere length as determined in 7 different fibres. Movement (active shortening) per se, apart from the change in sarcomere length, affected the kinetics of the active state. An interval of free shortening interposed during an isometric contraction reduced the fibre's capacity to produce tension for the rest of the contraction period without changing the total duration of the mechanical activity substantially. The movement produced a relatively small effect as long as the active state was maximum; the depressant effect became greater and greater, however, the later the movement occurred during the decay phase of the active state. The nature of the length and movement dependence of the active state is discussed in the light of the calcium‐activator mechanism of the excitation‐contraction coupling.
The Effect of Combined Respiratory and Nonrespiratory Alkalosis on Energy Metabolites and Acid‐Base Parameters in the Rat Brain
Authors: Granholm Lars , Siesjö Bo K. 
Published: December 2008

AbstractIn order to study the cerebral effects of a combined respiratory and nonrespiratory alkalosis, rats under nitrous oxide anesthesia were hyperventilated for 45 min. During the last 13 min, the animals were either injected with 5.5 mEq/kg of NaCl, or with an equimolar amount of NaHCO3. Both groups had arterial CO2 tensions close to 16 mm Hg, but the injection of sodium bicarbonate increased the arterial pH further from 7.58 to 7.80. In both hyperventilated groups, there were marked increases in the tissue lactate concentrations, and in the calculated lactatelpyruvate and NADH/NAD+ ratios. In the group injected with sodium bicarbonate there was a small further increase in the intracellular lactate concentration, but no significant changes in the extracellular lactate, pyruvate, or bicarbonate concentrations, or in the CSF pH. In none of the hyperventilated groups there were changes in the tissue contents of phosphocreatine, ATP, ADP or AMP indicative of clearcut tissue hypoxia.
Changes in the Action Potential and Contraction of Isolated Frog Muscle after Repetitive Stimulation
Authors: Persson J. Hanson and A. 
Published: December 2008

AbstractThe effect of repetitive stimulation of twitch fibres was studied in isolated whole muscle from Rana pipiens. Intracellular electrodes were used for recording membrane potentials, muscle tension was recorded isometrically and the decline of the active state of the contractile elements was determined by the quick release method. Repetitive stimulation caused an increase in the duration of the action potential and in the amplitude of the early negative after‐potential. To judge from experiments on fibres with disrupted transverse tubules, the increase in the duration of the action potential is due to changes in the surface membrane, while the increase in the amplitude of the after‐potential is related to the transverse tubules. The changes in the action potential and the after‐potential were independent of whether or not the muscle contracted and thus cannot be secondary to the contraction. The shape of the action potential and the after‐potential returned to normal within 5 min after stimulation at 10/sec for 60 sec while after 30 min there was still an increase in the peak twitch tension and a slower‐than‐normal decay of the active state in response to test shocks. This indicates that the post‐stimulatory potentiation is due to a prolonged active state which, in turn, is due mainly to causes other than changes in the action potential and after‐potential.
The Low‐Frequency Electrical Impedance of the Isolated Frog Skin
Authors: Smith P. G. 
Published: December 2008

AbstractThe electrical impedance of the isolated frog skin has been measured in the frequency range 0.05 Hz‐2 kHz. Under certain conditions, the resistance and capacitance of both outward‐facing and inward‐facing membranes can be estimated from these measurements. The inner membrane has a capacitance which is some 50 times greater than that of the outer membrane; the ratio of membrane areas is likely to have a similar value. The large area of the inner membrane would be explained if the interiors of all living cells in the epithelium were in electrical contact. With Ringer solution bathing both sides of the skin, the resistance of the inner membrane is much smaller than that of the outer membrane.
Effects of Vasoconstriction on Blood Viscosity in Vivo
Authors: Baeckström Peter , Folkow Björn , Kendrick Ed , Löfving Birger , ÖBerg Bengt 
Published: December 2008

AbstractThe influence of vascular dimensional changes on blood viscosity in vivo (“effective” viscosity) was analyzed in the calf muscle vascular bed of cats. Values for effective blood viscosity over an extensive flow range were obtained from comparisons of pressure‐flow curves for blood and a Newtonian fluid (Dextran‐Tyrode) with known viscosity. Such comparisons were made both at high and low flows during maximal vasodilataion and at low flows during vascular narrowing, caused either by vessel collapse or by intense, stable vasoconstriction as a result of barium chloride infusion. At indentical low flows effective blood viscosity was substantially lower in the constricted or collapsed bed than in the dilated and distended bed. With reduction of flow from maximal to very low values in the completely dilated, non‐collapsed bed effective blood viscosity increased from about 2.35 cP by 200–300 per cent. If the same low flows occurred as a result of intense vasoconstriction, implying a more than 5000 per cent increase of flow resistance, the viscosity increased by about 30 per cent.Apparently, effective blood viscosity is normally low and varies very little within the extensive flow range met with in vivo as a consequence of alterations of vascular tone. Therefore, even at extremely low flows in the constricted bed, as after severe blood loss, effective blood viscosity is hardly a significant determinant of flow, as long as blood composition is not changed.
The Effect of High Oxygen Tensions on Ventilation during Severe Exercise
Authors: Kozlowski S. , Rasmussen B. , Wilkoff W. G. 
Published: December 2008

AbstractThe effect of high oxygen tensions on ventilation during severe exercise was studied in four young male subjects to determine whether the change in ventilation is of humoral or of nervous origin (from chemoreceptors) or a combination of both. Accordingly, the time course of ventilation was determined in the transient from low to high oxygen tensions (air‐35 % O2, air‐100 % O2, 35–100 % O2) and from high to low oxygen tension (100 % O2‐air). Blood samples taken during the transient were analysed for Paco2, pH and lactate concentration. The full depressant effect on the ventilation of high oxygen tensions was obtained after 10–20 seconds, independent of the oxygen tension before the transient. The total ventilatory depression was approximately 14 % going from air‐100–% O2, 6 % going from air‐35 % O2 and 6 % from 35 % O2‐100 % O2. When the subjects went from high oxygen tension to a lower oxygen tension the ventilation became stable after 30–40 seconds. The ventilation came back to values a little higher than the control values.The changes in Paco2 and pH were opposite to what one could expect if they were causal factors. The change of blood lactate concentrations in the transients was too slow to explain the change in ventilation. In the period between the transients, high oxygen tensions had a sustained depressant effect on ventilation and a slight fall in blood lactate in this period could indicate a decreased anaerobicity in the working muscles. The similarity of the time courses in the transients at various conditions indicates that the initial ventilatory depression is caused by the same factors at rest and during exercise. If one assumes that the aortic and carotid chemoreceptors are responsible for the depression in ventilation, the threshold value of these receptors is changed during severe exercise, since 35 % O2 is not enough to silence the chemoreceptors.
Efflux of Prostaglandins in Lymph from Scalded Tissue
Authors: ÄNggård Erik , Jonsson Carl‐Evert 
Published: December 2008

AbstractÄnggård, E. and C.‐E. Jonsson, Efflux of prostaglandins in lymph from scalded tissue. Acta physiol. scand. 1971. 81. 440–447.The smooth muscle stimulating lipids present in lymph from scalded dog paws were examined by a variety of chromatographic procedures in combination with bioassay. It was shown that 85 to 98 5% of the smooth muscle stimulating activity of the lymph extract was also present in the acidic lipid fraction. On silicic acid chromatography with linear gradient elution nearly all of the biological activity (rat fundus strip) followed the radioactivity due to added 3H‐labelled prostaglandin E2 (PGE2). In reversed phase partition chromatography most of the smooth muscle stimulating activity appeared with the 3H‐PGE2. After treatment with alkali and conversion to the methyl ester triniethylsilylether the material was analyzed by gas chromatography with electron capture detection. A peak was observed with a retention time identical to that of the same derivative of authentic prostaglandin B2. When the smooth muscle stimulating activity isolated by silicic acid chromatography from the lymph was incubated with 15‐hydroxy‐prosta‐glandin dehydrogenase from swine lung in the presence of NAD+ complete biological inactiva‐tion was observed. It is concluded that most of the smooth muscle stimulating activity present in dog lymph after experimental burn injury is due to prostaglandin E2.
Pyruvate and Lactate Ratios in Muscle Tissue and Blood during Exercise in Man
Authors: Karlsson Jan 
Published: December 2008

AbstractKarlsson, J. Pyruvate and lactate ratios in muscle tissue and blood during exercise in man. Acta physiol. scand. 1971. 81. 455–458.To study the changes by exercise in the relationships betwen pyruvate (Py) and lactate (La) in muscle tissue and blood of man, Py and La were determined in muscle biopsy specimens (M. quadriceps fernoris) and in blood in 8 subjects at rest (I) and after submaximal (II) and maximal (III) bicycle exercise. In the resting muscle Py was 0.06 mmoles ×kg‐1 wet muscle and increased with exercise to 0.14 (II) and 0.13 (III) mmoles×kg‐l whereas La increased from 2.3 (I) to 10.4 (II) and 17.1 (III) mmoles×kg‐1 wet muscle. In the blood the corresponding values for Py were 0.11 (I), 0.24 (II), and 0.39 (III) mmoles×l‐1 and for La 1.6 (I), 7.7 (II), and 10.0 (III) mmoles×1‐1. Thus the La/Py ratio increased from 38 (I) to 74 (II) and 131 (III) in the muscle and from 15 (I) to 32 (II) and 26 (III) in the blood. The increase in the muscle Py concentration during exercise could not account for more than a very minor part of the muscle La concentration which means that the excess lactate (XL) is of very minor physiological importance.
Uptake of 5‐Hydroxytryptamine by Mast Cell Granules in vitro
Authors: Jansson S.‐E. 
Published: December 2008

AbstractMast cell granules were prepared from rat peritoneal cell suspensions by freezing, thawing and differential centrifugation. The granules were electron microscopically found to be membrane free. Incubation with 5‐hydroxytryptamine (5‐HT) resulted in an uptake which was not temperature dependent, which increased with increasing 5‐HT concentrations in the medium with little tendency to saturation, which was not blocked by sodium cyanide, dinitrophenol and FCCP and which was not accelerated by adenosine triphosphate and magnesium chloride. Reserpine and guanethidine affected little the endogenous 5‐HT content but effectively de pressed the uptake of 5‐HT by the granules. ‐Amitriptyline and prenylamine lowered the endogenous 5‐HT content and in some experiments depressed the uptake to some extent. Imipramine, chlorpromazine, cocaine and g‐strophantine had little or no effect on the endogenous content or uptake of 5‐HT. It is concluded that the membrane free granules take up 5‐HT from the medium by a passive process dissimilar from the active membrane dependent uptake mechanism in intact mast cells.
Histamine and Heparin Release from Isolated Rat Mast Cells Exposed to Compound 48/80
Authors: Slorach Stuart A. 
Published: December 2008

AbstractThe relationship between the release of histamine and heparin from rat mast cells exposed to compound 48/80 in vitro has been studied in order to elucidate the mechanism of action of this histamine releasing agent. Heparin is almost exclusively localized to the granule fraction of mast cells and therefore its release can be used as an index of granule release.The ratio percentage histamine release/percentage heparin release was found to be 1.4–1.7 and 1.6–2.0 following exposure of mast cells to 2.5 and 0.25 μg/ml respectively of compound 48/80. These “found” ratios are artificially high due to the fact that it is impossible to effect a complete separation of the released granules from the mast cells. Bearing this in mind, these results are consistent with the hypothesis (Uvnäs and Thon 1966) that the release of histamine‐containing granules is a primary event in the release of histamine induced by this agent. How ever, they do not exclude the possibility that part of the histamine release can take place without granule release. Studies of the specific activities of the 35S‐labelled heparin released and retained by mast cells taken from rats at different intervals after Na235SO4 injection and exposed to compound 48/80 suggest that the most mature granules are released first on treatment of mast cells with this substance.