bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of Autoregulation in Maintaining Glomerular Filtration Rate at Large Urine Flow
Authors: Kiil F. , Kjekshus J. , Löyning E.
Published: December 2008

The effects of large urine flow and high tubular pressure on renal blood flow (RBF) and glomerular filtration rate (GFR) were studied in dogs. In unanesthetized animals, ethacrynic acid and furosemide infused during hypotonic saline or mannitol diuresis increased urine flow to more than half of the filtered load without reducing GFR, whereas clearance of paraamino‐hippurate (CI’.VH) rose. In anesthetized dogs, ethacrynic acid and furosemide increased RBF. By stepwise renal artery constriction RBF was reduced in proportion to perfusion pressure, indicating abolished autoregulation. A similar moderate increase in RBF and abolition of autoregulation were also obtained by ureteral obstruction. In contrast, autoregulation was maintained until RBF was nearly doubled during infusion of saline or mannitol. During infusions of hypotonic solutions, CPAH increased despite reductions in serum osmolality which in renal perfusion experiments led to a fall in RBF.

Conclusion: High tubular or intestitial pressure acts on the autoregulating mechanism which dilates afferent arterioles until the hydrostatic pressure difference over the glomerular membrane is reestablished. By this mechanism, RBF is increased and GFR maintained at high urine flow. Vasodilating factors may be elicited during expansion of extracellular volume, but do not affect autoregulation and are without distinct effect on GFR.
A Comparative Study of K42 and Na24 Movements during the Cardiac Cycle
Authors: Coraboeuf E. , Delahayes J. , Sjöstrand U.
Published: December 2008

Studies of K42 and Na24 movements during the cardiac cycle were made on right ventricle from the rat and guinea‐pig, on frog atrium and on frog ventricular strips. The methods used in these studies have been described in earlier papers cited in the text. The K42 study showed a cyclic leakage of radioactive potassium from the rat ventricle: no such leakage was observed in ventricle from the guinea‐pig. Both frog preparations showed an increase of K42 efflux during the electrical activity. The Na24 study showed a slight decrease in the radioactive sodium efflux from the rat and guinea‐pig ventricle at the depolarization phase and the first part of the action potential; in frog preparations a large increase in the activity efflux preceded by a slight decrease was observed. The possibility of mechanical artifacts is discussed and an interpretation of the results is proposed which is based on a different pattern of potassium permeability between the species, the guinea‐pig and frog showing a “rectangular” action potential and the rat a “sigmoid” action potential. The slight decrease in Na24 activity preceding the mechanical systole could reflect the basic ionic mechanisms of the depolarization.
Embryological Observations of the Ductus Arteriosus in the Guinea‐Pig, Rabbit, Rat and Mouse. Studies on Closure of the Ductus Arteriosus. IV
Authors: Hornblad P. Yngve
Published: December 2008

Fetuses of guinea‐pigs, rabbits, rats and mice were obtained by caesarean section in late pregnancy. They were immediately sacrificed, and fixed by whole‐body freezing, after which transverse cryostat sections of the ductus arteriosus were prepared for morphological observations. The inner diameter and wall thickness of the ductus were measured at its narrowest part. The descending thoracic aorta of full‐term rat fetuses was treated in the same way as the ductus.

In all species, the mean inner diameter of the ductus increased with fetal age, and was accompanied in the guinea‐pig and rabbit by a gain in thickness of the media. The development of an intima was most evident in rabbit fetuses. In all species, the structure of the ductal wall was comparable in the youngest and oldest fetuses.

The inner diameter and wall thickness of rat and mouse fetuses near term corresponded well to values in newborns. The divergent values between fetuses and newborns of the guinea‐pig and rabbit are discussed. The relation recorded between the cross‐sectional areas of the ductus arteriosus and thoracic aorta is in agreement with the present concepts of prenatal circulation.

The similarities in ductal morphology between full‐term fetuses and newborns might justify the use of full‐term fetuses in experiments on the physiology of the ductus arteriosus.
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

The 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

Before, 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

Studies 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

The 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

The spectral integration of single units in the rat's cochlear nucleus has been investigated by two different methods, namely

1. 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

Unitary 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

Osmotic 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

The 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

In 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

The 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

The 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

The 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

The 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

Änggård, 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

Karlsson, 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

Mast 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

The 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.
Effect of Prolonged Strenuous Exercise on the Concentration of Triglycerides, Phospholipids and Glycogen in Muscle of Man
Authors: Fröberg Sven O. , Mossfeldt Folke
Published: December 2008

Muscle tissue from the lateral vastus of the femoral muscle was taken by needle biopsy technique in 7 male subjects before and after strenuous exercise by skiing for about 7 hrs. The mean muscle triglyceride concentration decreased from 17 to 8 μmoles/g wet weight during the exercise. No change was observed in the phospholipid concentration. The mean glycogen concentration in the muscle decreased from 16 to 7 mg/g sswet weight during the exercise. The results indicate that not only muscle glycogen but also muscle triglycerides are of importance for the energy metabolism in man during exercise.
Effect of Prolonged Physical Training on the Catecholamine Levels of the Heart and the Adrenals of the Rat
Authors: ÖStman Ingegerd , Sjöstrand Nils O.
Published: December 2008

The effect of prolonged physical training on the noradrenaline content of the heart and the catecholaniine content of the adrenal glands was studied on rats. the trained rats showed a moderate but highly significant cardiac hypertrophy (heart weight of controls: 1.32±0.01, trained rats: 1.41 ±0.01, heart ratio (g heart weight/100 g b.w.) of controls: 0.29 ± 0.003, trained rats: 0.34 ± 0.003). There was no difference in cardiac noradrenaline concentration between trained and untrained rats (controls: 0.69±0.04 μg/g, trained rats: 0.73±0.03 μg/g). There was a highly significant increase in adrenaline content of the adrenal glands espressed as μg adrenaline/kg b.w. (Controls 93±5 μg/kg, trained rats: 122 ± 5 μg/kg). It is concluded that prolonged physical training does not lower the amounts of synipatlictic trans mitter of the heart. It is further suggested that an increased adrenaline content in the adrenal glands might be a manifestation of an adaptation to the increased demands upon the rardio vascular system in rats subjccted to prolonged physical training.
Efflux of Prostaglandin E, from Cat Paws Perfused with Compound 48/80
Authors: ÄNggård Erik , Strandberg Kjell
Published: December 2008

Effluents from cat paws perfused with compound 48/80 contained histamine and lipid‐soluble smooth muscle stimulating principles. Fractionation of the lipid‐soluble material on silicic acid resulted in a separation into two major components with different biological properties. One component was of polar character and elicited a slow, sustained contraction of the isolated guinea‐pig ileum. These are effects associated with “slow reacting substance” (SRS) by definition. The other component being less polar was examined by a variety of chromatographic procedures in combination with bioassay. In silicic acid chromatography with linear gradient elution and in reversed phase partition chromatography all biological activity followed the radioactivity due to added 3H‐labelled prostaglandin E2 (PGE2). On thin layer chromatography the smooth muscle stimulating compound cochromatographed with reference PGE2. When the spasmogenic compound isolated by silicic acid chromatography was incubated with 15‐hydroxy prostaglandin dehydrogenase from swine lung in the presence of NAD+ complete biological inactivation occurred. Determination of ester‐bound C20 fatty acids in cat skin by gas chromatography revealed that arachidonate, precursor of PGE2, was the most abundant prostaglandin precursor acid. When 3H‐PGE2 was infused into cat paws the parent compound as well as two metabolites, 13,14‐dihydro‐PGE2 and 15‐keto‐13,14‐dihydro‐PGE2, appeared in the effluent. It is concluded that PGE2 constitutes part of the lipid‐soluble spasmogenic material appearing in connection with histamine release in the cat paw induced by compound 48/80.
The Quantitative Inhibition of Triton Lipemia with Heparin in Rats
Authors: Haikonen Matti , Räsänen Toimi , Räsänen Vesa , Taskinen Eero
Published: December 2008

The effect of exogenous heparin on triton lipemia induced in rats was studied in 2 expts. 5×25 mg of Triton WR‐1339 injected at intervals of 12 hrs caused an abrupt increase in the blood cholesterol and fat levels. They were both lowered distinctly by 50 IU of heparin injected concomitantly with triton. In the second experiment, 3×25 mg of triton provoked a smaller but significant elevation in the lipemia of rats. 3 × 250 IU of heparin nullified the hypercholesterinemia and the lipemia completely. Smaller doses of heparin caused a gradually diminishing inhibition of triton induced lipemia. The results of these two experiments and one of our earlier experiment suggest that Triton WR‐1339 inhibits the release of heparin especially from the mucosal mast cells of gastrointestinal tract. Triton does not inhibit the activation of the clearing factor with exogenous heparin. Under these circumstances, it is possible to measure the shortage of endogenous heparin by replacing it with exogenous heparin using the level of lipemia as indicator.
Purification and Properties of the Slow Reacting Substance Formed in the Cat Paw Perfused with Compound 48/801
Authors: Strandberg Kjell , Uvnäs Börje
Published: December 2008

Cat paws were perfused with a physiological salt solution containing compound 48/80. In addition to histamine, a principle producing a slow sustained contraction of the isolated guinea‐pig ileum appeared in the effluent. This slow reacting substance (SRS) was purified by ethanol extraction, solvent partition, silicic acid and anion exchange chromatography. The overall recovery was 10–20 per cent, calculated from the non‐histamine smooth muscle stimulating activity of the ethanolic extract. The purification calculated from the crude lipid extract was about 200‐fold. The purified material was dialysable, thermostable at neutral pH and more labile in acid than in alkaline milieu. It behaved homogenously on thin layer chromatography in several systems. The most marked biological effects were contraction of the isolated guinea‐pig ileum and the human bronchus, increases in the bronchial resistance in guinea‐pigsin vivo, in the colouration (Evan's blue dye i.v.) of guinea‐pig skin after intradermal injection and in the blood flow in the cat hindlimb after intraarterial injection. Treatment of the purified material with N, N'‐carbo‐di‐p‐tolylimide, phenyl isocyanate, iodine monobromide, potassium permanganate or acetic anhydride abolished or greatly reduced the biological activity. Incubation of SRS with 15‐hydroxy prostaglandin dehydrogenase in the presence of NAD+resulted in no loss of biological activity. Together the results indicate that SRS is a biologically active carboxylic acid with hydroxyl groups and one or more double bonds but probably of non‐prostaglandin nature.
Hyperosmolarity and Pulmonary Vascular Capacitance
Authors: Bø G. , Nicolaysen G.
Published: December 2008

Since plasma osmolarity rises during general muscle exercise and the lung is thought to have a function as a blood depot we have investigated the effect of plasma hyperosmolarity on pulmonary vascular capacitance. Hyperosmolar solutions of sodium chloride, urea and ethylene‐glycol (listed in order of potency) were infused into the pulmonary artery of an isolated rabbit lung preparation perfused with plasma at constant volume pulsatile inflow and ventilated by positive pressure. All the test‐substances caused dose‐dependent reductions in the weight of the preparations, which was followed continuously by the use of a force transducer. The effect was not related to change in bronchomotor tone or pulmonary vascular pressures. Nor could the weight reductions be explained solely as a result of loss of water from the lungs. The capacitance vessels of the lung appear to constrict when exposed to increased plasma osmolarity, a response which is in direct contrast to the effect of this stimulus on the resistance vessels of the lung. The finding strengthen the concept of the lung as a blood depot.
Ultrastructural Studies of the Alveolar‐Capillary Barrier in Isolated Plasma‐Perfused Rabbit Lungs. Effects of EDTA and of Increased Capillary Pressure
Authors: Hovig T. , Nicolaysen Anne , Nicolaysen G.
Published: December 2008

The ultrastructure of lung capillaries and of lung interstitiuni has been studied in isolated. ventilated and plasma‐perfused rabbit lung preparations at different levels of perfusate [Ca++] and [Mg++] (achieved by EDTA additions). A perfusion fixation niethod was applied, and situations where net fluid transfer over the capillary wall was taking place could therefore be studied with some confidence. No morphological changes were found which could explain the increased capillary permeability to proteins during EDTA‐induced edema development. Ultra‐structural alterations of the capillary walls were similarly not observed during periods of increased hydraulic conductivity of the lung capillaries caused by lower concentrations of EDTA than those releasing edema. In all experiments where net outward flux of fluid from the capillaries had taken place at the moment of fixation, one could observe electron lucent zones (laminae rarae) of the basement membranes which were much more distinct than in control specimens. This phenomenon could be related to the process of capillary fluid leakage, which thus may take place also in the regions of the vessel wall wheie the alveolar‐capillary barrier is at its thinnest.
Stability of [Mg2+] in Cerebrospinal Fluid during Plasma Changes and during Hypercapnia in Young and in Adult Rats
Authors: Olsen O. M. , Sørensen S. C.
Published: December 2008

This investigation was undertaken to examine whether the rat, like other mammals that have been studied, maintains a stable concentration of Mg2+ in cerebrospinal fluid (CSF) when the plasma Mg2+ concentration is changed. CSF was sampled from the cisterna magna in adult rats made hypomagnesemic by being fed a magnesium‐free diet. The [Mg2+] in CSF did not decrease significantly during hypomagnesia, in disagreement with previous findings in the rat. The disagreement could have been due to a difference in the age of the animals when they were studied, cation transport processes possibly being incompletely developed in young rats, but we found that rats 3 to 4 weeks old also maintained a stable [Mg2+] in CSF during hypo‐niagnesemia. The effect of 4 hrs of hypercapnia on the [Mg2+] in CSF was examined in normal hypomagnesemic adult rats. Hypercapnia did not affect the [Mg2+] in CSF in either group.
Ca++ Dependence of Histamine Release and Formation of Slow Reacting Substance in the Cat Paw
Authors: Strandberg Kjell
Published: December 2008

The influence of divalent cations on the release of histamine and the formation of slow reacting substance (SRS) in the perfused cat paw induced by compound 48/80 was studied. Ca++ was found to have a stimulatory effect on both processes. Ca++ had no releasing effects per se. When the paws were perfused for 1 or 2 hrs with Ca++‐free salt solution, prior to compound 48/80, the release was depressed. Histamine release and formation of SRS were inhibited by disodium ethylene diamine tetraacetate (EDTA). In both instances the EDTA‐blockade could be reversed by Ca++, whereas Ca++, Mg++, Mn++ and Ni++ were ineffective substitutes. The EDTA‐blockade of histamine release but not that of the formation of SRS was also reversed by Sr++ and in some experiments by Ba++. The stimulatory effect of Sr++ on the release of histamine was weaker than that of Ca++. No significant stimulatory effect of Sr++ on the formation of SRS was observed. It is concluded that the release of histamine and the formation of SRS in the cat paw are Ca++‐dependent processes although in the case of histamine release Ca++ can partially be replaced by Sr++.
Changes in Cerebral Blood Volume of Mice at Various Time‐Periods after Superior Cervical Sympathectomy
Authors: Edvinsson L. , Owman Ch. , West K. A.
Published: December 2008

The relative blood volume in the brain of mice was estimated after distribution in the blood stream of intravenously administered131I‐labelled human serum albumin. The alterations in the blood volume was studied at various time‐periods after bilateral excision of the superior cervical ganglia. The blood volume was found to remain unchanged during the first 6 hrs post‐operatively. At 12 hrs it was reduced by 28 per cent, whereas after 24 hrs it had increased to a level 34 per cent above that in the unoperated control animals. The volume then normalized at 4 days after sympathectomy, and even tended to be subnormal after 2 weeks. It is suggested that the initial reduction in blood volume is caused by vasoconstriction as a result of the leakage of noradrenaline from the vascular adrenergic nerve terminals starting a few hours after sympathectomy. The resulting degeneration activation of the smooth muscle receptors is known to subside within about 24 hours at which time a vasodilatation was found to occur. It is probable that the vascular tone then returned to the preoperative or an even more pronounced degree due to the progressive development of supersensitivity of the denervated vascular receptors to normally circulating catecholamines.
The DC Potential between CSF and Plasma in Respiratory Acidosis
Authors: Messeter Kenneth , Siesjö Bo K.
Published: December 2008

The electrical DC potential between cisternal cerebrospinal fluid and jugular venous blood was measured in rats during respiratory acidosis and alkalosis. In one of the main series studied, respiratory acidosis and alkalosis was upheld for 5, 15, 45 and 180 min in animals anesthetized with nitrous oxide. In the other main series, sustained hypercapnia was induced by exposing unanesthetized rats to about 5 or about 11% CO2 for 3, 24 and 48 h, respectively. In this series, the animals were anesthetized during the last 30–45 min of the hypercapnia. In acute respiratory acidosis and alkalosis, the CSF‐plasma potential difference varied linearly with the plasma pH with a slope of about ‐27 mV/pH unit. The CSF‐plasma potential differences measured in sustained hypercapnia did not deviate significantly from the mean regression line calculated from the acute experiments. The results thus showed that the CSF‐plasma potential difference was not only increased during acute respiratory acidosis, but also remained increased as long as the plasma pH was acid.
Changes in Continuously Recorded Intracranial Pressure of Conscious Rabbits at Different Time‐Periods after Superior Cervical Sympathectomy
Authors: Edvinsson L. , Owman Ch. , West K. A.
Published: December 2008

The intracranial pressure, measured as the ventricular fluid pressure (VFP), was recorded continuously during about 2 days via a cannula inserted into the left lateral ventricle of the brain of conscious rabbits. The effect of bilateral removal of the superior cervical ganglia on the VFP was studied at various time‐periods after operation, and the results were compared with those from unoperated control animals. The pressure changes attributed to the sympathectomy are referred to as the net VFP. The operation ultimately caused a disappearance of noradrenaline from intracranial sympathetic nerves. The net VFP was not affected during an 8‐hr period of the recording starting 5–8 hrs after sympathectomy. During the following 35 hrs it was reduced by approximately 25 mm physiological saline followed by a return to initial or somewhat higher levels. Four days after sympathectomy the net VFP was significantly increased throughout the recording period. Two weeks after the operation the pressure had returned to the same, or even lower level compared with the non‐sympathectomized control animals. The variations in the net VFP at different time‐periods after sympathectomy are considered to reflect mainly changes in the intracranial vascular bed due to the leakage and disappearance of the noradrenaline transmitter from the degenerating nerve terminals followed by denervation supersensitivity. The results are discussed in terms of a sympathetic influence on the intracranial pressure mediated through the volume of the intracranial vascular bed, and/or the cerebrospinal fluid production in the choroid plexuses.
Nervous Influence on the Pulmonary Capacitance Vessels in the Rat
Authors: Aarseth Petter
Published: December 2008

It has previously been shown in experiments on rats that the pulmonary capacitance vessels play an important role as a blood depot in this species. In the present experiments one has attempted to evaluate the vasomotor nervous influence on this depot. Pulmonary blood volume was estimated from measurements of 128I‐tagged albumin and 51Cr‐tagged erythrocytes in the excised lungs of rats which had been rapidly frozen in liquid nitrogen. Partial pulmonary denervation was achieved beforehand in two groups of animals by cutting the left thoracic vago‐sympathetic nerve trunk. Animals from one of these groups were frozen without further treatment, whereas those from the other group were exposed to a standardized blood loss immediately before being immersed in liquid nitrogen. When compared to the situation in control animals the left lung from animals of both the above groups contained relatively more blood than did their right lung. Furthermore the total pulmonary blood volume was found to be increased in animals with such partly denervated lungs. The reduction in pulmonary blood volume observed subsequent to a blood loss, was less marked in animals where the left vago‐sympathetic nerve trunk had been cut than in animals with intact pulmonary innervation. It is concluded that the pulmonary blood volume in the rat is influenced through vasomotor nerves both when a blood loss has taken place and during normal circulatory conditions.
Effect of Reduced Perfusion Pressure on Intrarenal Distribution of Blood Flow in Dogs
Authors: Løyning E. W.
Published: December 2008

Experiments by Barton et al. (1968) and Hollenberg et al. (1968) suggested that renal sodium excretion may be regulated by the distribution of blood flow within the kidney. Such a mechanism might account for the reduction in sodium excretion during lowering of arterial perfusion pressure, despite constant glomerular filtration rate and total renal blood flow (RBF). In the present study, renal blood flow in the outer half of the cortex (OCF) and inner half of the cortex (ICF), and in outer medulla (MBF), was examined during reductions of mean renal arterial pressure (RAP). RAP was reduced in steps by a clamp on the aorta or the renal artery, and at each pressure reduction OCF and ICF (cortex group, 7 dogs) and MBF (medulla group, 11 dogs) were measured by polarographic recording of hydrogen gas clearance with platinum electrodes inserted in the cortex, 2–3 mm and 6–7 mm respectively, and in outer medulla. RBF was measured by an electromagnetic flowmeter. At control pressure, OCF averaged 3.26 ml/min · g and ICF 3.45 ml/min · g, the difference between them being insignificant. An average decrease in RAP from 131 mm Hg to 76 mm Hg caused a 1% decrease in RBF and decreases in OCF and ICF to 89% (range 77–98%) and 87% (range 75–94%) respectively, both in per cent of control. The difference between OCF and ICF during clamping was not significant. At an average decrease in RAP from control of 126 mm Hg to 88 mm Hg, RBF decreased to 96% of control; MBF was not reduced (range 81–116%). The difference between changes in MBF and RBF was not significant. Atropinization did not change the pressure‐flow relationship of outer medulla.