bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aortic Baroreceptor Activity during Permanent Distension of the Receptor Area
Authors: Aars Harald 
Published: December 2008

AbstractAortic baroreceptor activity is known to be reduced in cases of persisting hypertension, the resetting probably resulting from changes in the aortic wall. The present investigation is an attempt to study the effects of permanent, localized dilatation of the aortic baroreceptor area on receptor activity. Ascending aortic stenosis was produced in 24 rabbits, and aortic diameters and aortic nerve activity were compared with results obtained in 10 normal rabbits. Aortograms four weeks after production of the stenosis showed diameters in the upper part of the ascending aorta and the aortic arch to be on average 16 % and 13 % greater than normal. Whereas an acute dilatation of this degree would have given marked increases of aortic nerve activity, the relationship between pressure and receptor activity was normal in animals with a permanent dilatation, both at pulsatile and steady pressures. The load‐length relationship of aortic strips from normal and dilated receptor area was also equal, indicating that the uniformity of the relationship between pressure and activity in the two situations, at least in steady states, was due to adaptation of the aortic wall. It thus seems that chronic increases of neither pressure nor receptor area diameter will have consequences for aortic baroreceptor activity.
Mechanical and Electrical Responses to Single Shocks in Developing Cat Leg Muscles Following Tetanization
Authors: Nyström Bo 
Published: December 2008

AbstractThe effects of 9 sec tetanizations of varying frequencies on isometric twitch and electrical responses were studied in the gastrocnemius, soleus and extensor carpi radialis longus (ECRL) muscles of kittens of varying ages and adult cats. Nembutal® anaesthesia was used. In newborn kittens, no or only slight post‐tetanic twitch potentiation (PTP) was recorded in the gastrocnemius muscle, but a PTP of 80–90 % in the soleus. With time, twitch potentiation increased in the gastrocnemius and decreased in the soleus. In the latter muscle of adult cats, PTP was obtained only after high‐frequency tetanization (250–450 clsec). This PTP proved to be due to repetitive activity, and of different magnitude in Nembutal‐ and chloralose‐anaesthetized animals. Changes in contraction and half relaxation time and in tension rise of the twitches occurred post‐tetanically. At all ages, post‐tetanic muscle action potentials, whether accompanying potentiated twitches or not, showed no consistent change in size, varying ± 10 % from the pre‐tetanic values. In young kittens, post‐tetanic potentials were slightly delayed. In the gastrocnemius and ECRL of adult cats, there was a short‐lasting increase‐as compared to the duration of twitch potentiation‐in duration of the electrical response, but no change in latency. It is concluded that, in Nembutal‐anaesthetizd animals, repetitive firing accounts for PTP in the adult cat soleus muscle. The PTP in the soleus of young kittens and in the gastrocnemius and ECRL of the adult animals is, on the other hand, due either to a change within the contractile mechanism of the muscle fibres, or to a recruitment of muscle fibres.
Effect of Potassium‐Magnesium‐Aspartate on the Capacity for Prolonged Exercise in Man
Authors: Ahlboro Björn , Ekelund Lars‐Göran , Nilsson Carl‐Gustaf 
Published: December 2008

AbstractThe effect of potassium‐magnesium‐aspartate on the capacity for continuous prolonged standardized physical exercise (exercise times about 90 min) has been investigated in 6 normal young men. After administration of potassium‐magnesium‐aspartate the capacity for prolonged exercise increased about 50 per cent. Possible mechanisms behind this effect are discussed.
On the Physiological Significance of the Shape of the Endosomatic Galvanic Skin Reaction in the Cat
Authors: Lang A. H. 
Published: December 2008

AbstractEndosomatic galvanic skin reactions (GSR) have been evoked in cats by single or repetitive stimulation of the distal stump of a sectioned sciatic nerve. The GSRs were recorded with macroelectrodes from the surface of the central pad of the cat's paw. ‘The shape of the “single” GSR induced by a single impulse is fairly constant in a given preparation. The shape of the “fused” GSR induced by tetanic stimulation is, however, variable and generally intermediate between two extreme types, a “slow” and a “fast” type. A stimulation of low intensity and frequency and arwst of the regional blood flow causes the reaction to change in the direction of the “slow” type. The “fused” GSR induced after a period of rest often still deviates greatly from the mentioned extreme types. The shape of the ascending phase of the“fu:ed” GSR is decisively determined by the frequency and intensity of the stimulation. The view is presented that the factors responsible for the observed systematic variations in the shape of the “fused” GSR may be those which cause changes in the amplitude of the “single” GSR with constant stimulus parameters and in the d.c. potential level of the skin. Changes in the impedance of the skin seem to play a central role in these mechanisms.
Metabolism of Dopamine and Noradrenaline in Normal, Atrophied and Postganglionically Sympathec‐ tomized Rat Salivary Glands in vitro
Authors: Jonason Jan 
Published: December 2008

AbstractSlices from normal, atrophied and postganglionically sympathectomized rat salivary glands were incubated with labeled dopamine or noradrenaline. The catabolism of dopamine proceeded at a higher rate than that of noradrenaline. This phenomenon is proposed to be due to the higher affinity of dopamine for monoamine oxidase, the extraneuronal part of which being very important. The major catabolites of dopamine were found to be the phenolic acids dihydroxy‐phenylacetic acid and homovanillic acid. Exogenously added noradrenaline was primarily catabolized to normetanephrine, whereas the major metabolites of newly synthesized noradrenaline from dopamine were the phenolic glycols 3,4‐dihydroxyphenylglycol and 3‐methoxy‐4‐hydroxyphenylglycol, supporting the view that intraneuronally formed noradrenaline initially is metabolized by intraneuronal monoamine oxidase prior to its O‐methylation by catechol‐O‐methyl transferase. Atrophy reduced the levels of all 3‐O‐methylated products, especially those of the methoxylated amines, whereas sympathectomy increased the amounts of these amines and diminished the deaminated products. Thus, catechol‐O‐methyl transferase is localized to the parenchymal cells in the salivary glands. In contrast to the dopamine metabolism, the catabolism of noradrenaline was more affected by postganglionical sympathectomy than by atrophy. The data from the present study demonstrate the importance of the amine concentrating mechanism of the adrenergic nerve cell membranes.
“Concussive Response” and Intracranial Pressure Changes at Sudden Extradural Fluid Volume Input in Rabbits
Authors: Rinder Lennart 
Published: December 2008

AbstractAn extradural fluid volume (0.04–1.0 ml) was suddenly applied to the parietal brain surface in rabbits by means of a plunger system, attached to a hole in the skull. The immediate changes in arterial blood pressure, pulse rate and respiration were recorded and used as criteria of a “concussive response”. These pathophysiological effects were related to peak amplitude (0.1–3.0 atm.) and duration (5–300 msec) of the recorded intracranial pressure pulse. Similar pathophysiological effects could be reproduced by application of the same single load to the brain through a series of experiments. The “severity” of the concussive response varied with the peak amplitude and duration of the intracranial pressure pulse. At pressure pulses of 5–15 msec duration no pathophysiological effects occurred with a pressure pulse not exceeding about 0.7 atm. peak amplitude, but at 2.5 atm. peak pressure irreversible apnea was produced. Decrease in blood pressure occurred at induction of pressure pulses of comparatively low magnitude while a sudden increase in blood pressure was produced at pressure pulses of higher magnitude. Duration of apnea increased with increasing peak amplitude of the pressure pulse and seems to be a useful measure of the “severity” of the concussive response in the present type of brain trauma.
Isolation of Fibrinopeptides Formed during Intravascular Coagulation in Dogs
Authors: Grondahl Nils J. , Miller Sherwood P. , Teger‐Nilsson Ann‐Catrine 
Published: December 2008

AbstractPurified canine fibrinopeptide A was incubated in canine serum in vitro. The trichloroacetic acid‐soluble degradation products were isolated by preparative electrophoresis, and identified by means of amino acid analyses. Desarginino‐fibrinopeptide A and free arginine were found, indicating that C‐terminal arginine is split off from fibrinopeptide A during incubation in serum in vitro. An attempt was made to isolated fibrinopeptides and possible fibrinopeptide degradation products from the blood of thrombin‐treated dogs. A slow intravenous infusion of thrombin was given to dogs, until the blood became non‐clottable. Non‐protein material of the “plasma” was subjected to gel filtration, ion‐exchange chromatography and preparative electrophoresis. Two fractions, which could be related to the fibrinopeptides, were identified. The electrophoretic mobility of the fractions and of their tryptic digests, as well as the amino acid analyses, indicated that one fraction consisted of fibrinopeptide A and the other of desarginino‐fibrinopeptide A.
A Procoagulant from Human Postpartum Serum Effects on coagulation and hemodynamics in dogs
Authors: Nordstrom Sam , Olsson Per , Teger‐Nilsson Ann‐Catrine , Zetterqvist Eric 
Published: December 2008

AbstractA procoagulant, isolated from human postpartum serum, and concluded to be a tissue thromboplastin, was injected i.v. into dogs. The procoagulant induced a fall in fibrinogen and prothrombin concentration, an increased elimination rate of labelled fibrinogen, a pronounced drop in platelet count and hypotension. The results indicate that the procoagulant can induce intravascular coagulation. In this respect, it behaves like tissue thromboplastin.
The Effect of Secretin and Pancreozymin on Pancreatic Blood Flow in the Conscious and Anesthetized Dog
Authors: Aune S. , Semb L. S. 
Published: December 2008

AbstractPancreatic blood flow was studied in dogs by measuring local hydrogen gas clearance. External pancreatic secretion was collected by cannulation for volume measurements. In 16 expts. (15 dogs), recordings were obtained in pentobarbital (Nembutal) anesthesia. The mean value of 115 observations was 42.8 (S.E. 4.3) ml/min. 100 g pancreas. In 3 dogs, measurements were made in the awake, fasted state by means of chronically implanted electrodes, which proved effective for about two weeks. Mean of 33 observations was 76 ml/min. 100 g. The correlation between pancreatic blood flow and external secretion was studied by means of secretin (Boots, Jorpes) and pancreozymin (Boots). A variable response occurred, which proved to be time‐dependent and not correlated to the state of secretion or stimulation. An acute rise in blood flow was seen when hormone administration was started or increased. This effect was immediate but transient; blood flow returned to pre‐stimulatory level after 20 min, whereas the external secretion continued unchanged. No effect was noticed on gastric hydrogen clearance recorded in 4 of the dogs, indicating an organ specificity of the hormonal influence.
Distribution of Noradrenaline Storing Particles in Peripheral Adrenergic Neurons as Revealed by Electron Microscopy
Authors: HÖKFELT TOMAS 
Published: December 2008

AbstractThe cell bodies, the axons and the terminal parts of peripheral sympathetic neurons originating in the superior cervical ganglion and terminating in the dilator muscle of the iris were investigated in the rat by electron microscopy using potassium permanganate as a fixative. In all parts of the neuron granular vesicles were found. They were most numerous in the axonal enlargements of the nerve terminals, although also high numbers were found in some cell bodies, mostly localized in clusters in the peripheral parts of the cytoplasm. Two types of granular vesicles were found with a mean diameter of 495 Å (small) and 967 Å (large), respectively. The small granular vesicles were in majority, constituting about 98 per cent in the axonal enlargements in the dilator muscle of the iris. The number of vesicles in the axonal enlargements varied widely from 45 to 852 per enlargement. In all probability the small granular vesicles are the main storage site of noradrenaline in the peripheral adrenergic neurons. However, also the large ones probably contain an amine or at least are involved in the amine metabolism.
The Regulation of Extra‐ and Intracellular Acid‐Base Parameters in the Rat Brain during Hyper‐ and Hypocapnia
Authors: Kjäixquist Å. , Nardini M. , Siesjö B. K. 
Published: December 2008

AbstractThe influence of hyper‐ and hypocapnia upon extra‐ and intracellular acid‐base parameters in the brain was studied in rats anaesthetized with nitrous oxide. The arterial CO2 tension was held constant at various values between 12 and 90 mm Hg for 45 min. Assuming a 12 per cent extracellular volume, the intracellular buffer capacity (β= d log Pco2/d pH) could be calculated to 2.27, the intracellular bicarbonate concentration to 14.3 meq/kg of cell water and the equivalent intracellular pH to 7.10 at a tissue C02 tension of 40 mm Hg. Between the tissue Pco2 levels of 20 to 90 mm Hg the CSF bicarbonate varied by 19.5 meq/kg while the corresponding change in the intracellular bicarbonate concentration could be calculated to 12 meq/kg of intracellular water. The calculated buffer capacity of the CSF and intracellular phases greatly exceeded that of arterial blood in vivo. However, the buffering was not constant at different CO2 tensions but increased at low C02 tensions to approach infinite buffering power at extreme hyperventilation. The varying buffer capacity indicates that pH in the extra‐ and intracellular spaces of the brain is regulated not only by physicochemical buffering but also by metabolic mechanisms. The results strongly suggest that the metabolic control is partly exerted by variations in the lactic acid production since the progressive increase in the calculated buffer capacity at low CO2 tensions was parallelled by a continuously increasing lactate concentration, and since the constant buffer capacity at CO2 tensions exceeding 50 mm Hg was associated with lactate concentrations which hardly varied at all.
Turnover of H3‐Labelled Palmitate in the Unanesthetized Rat
Authors: Boberg Jonas 
Published: December 2008

AbstractThe turnover rate of blood plasma FFA has been studied in unanesthetized rats by single injection as well as constant infusions of albumin bound palmitic‐9,10‐H3 acid. The turnover was found to be about 50, μmoles/min per kg body weight with both techniques. The mean half life time of FFA was estimated to 17 sec with no significant difference between fed and fasted rats.
Catechol and Indole Derivatives in a Transplantable Islet‐Cell Tumour of the Golden Hamster
Authors: Cegrell Lennart , Falck Bengt , Rosengren Anna‐Maria 
Published: December 2008

AbstractNo adrenergic nerves were found in the transplantable islet‐cell tumour of the golden hamster studied in this investigation, but the tumour cells displayed an intense formaldehyde‐induced fluorescence. Chemically, not only were dopa, dopamine, and 5‐hydroxytryptamine found in the tumour, but also a hitherto unidentified substance capable of forming a fluorophore with formaldehyde. There is evidence that the fluorophore of this substance dominates in tumour cells and makes it impossible to register the presence of dopa, dopamine, and 5‐hydroxytryptamine in the microspectrograph. The fluorescence microscopic analyses of the endocrine pancreas of the tumour‐bearing animals did not reveal any differences from normal hamsters. Thus, these golden hamsters with an islet cell tumour should be of great importance in further studies aimed at understanding the biological significance of the monoamines in the hormone production, as there are two quite different insulin producing cell systems: the islets of Langerhans and the tumour cells. The islets of Langerhans contain no demonstrable amount of mono‐amines in the islet cells–in contrast to many mammalian species–but a rich supply of adrenergic nerves. The islet cell tumour contains a large concentration of monoamines in the tumour cells but no adrenergic nerves.
Determination of Inulin, Albumin and Erythrocyte Spaces in the Bone Marrow of Rabbits
Authors: Michelsen Kåre 
Published: December 2008

AbstractIn 20 young rabbits weighing between 1.0 and 2.0 kg, inulin space, albumin space and erythrocyte space were determined simultaneously in the bone marrow of the femur by use of inulin‐carboxyl‐14C, 125I‐labelled homologous albumin and 51Cr‐labelled autologous erythrocytes. The mean inulin space was 22.5 ml per 100 g tissue, the mean albumin space 18.8 ml and the mean erythrocyte space 3.2 ml. These results indicate that albumin passes the sinusoidal walls and is distributed throughout the extracellular space of the bone marrow.
The Effect of Aldosterone in vitro on the Active Sodium Transport and Moulting of the Frog Skin
Authors: Nielsen Robert 
Published: December 2008

AbstractIt is shown that aldosterone in concentrations higher than 1.5 · 10–9 M induces a moult in vitro, and that the moult is accompanied by characteristic changes in the potential and the short‐circuit current. The sequence of changes can be divided into four parts: the first constant period, the inhibition period, the spontaneous activation period and the second constant period. At a concentration of 7 · 10–7 M aldosterone the inhibtion starts 2–4 hrs and the activation 4–7 hrs after the addition. Furthermore it has been shown that the short‐circuit current is higher in the second constant period as compared to the control skin half. During the spontaneous activation period the net sodium flux exceeds the short‐circuit current by 25 %. The changes in chloride flux and sodium efflux during the moulting cycle were rather small. Both the moult and the activation of the short‐circuit current were abolished by actinomycin D. A hypothesis which could explain the behavior during the moulting cycle and the activation of the sodium transport is given.
The Heat Regulation of the Human Body
Authors: Pedersen Lorents 
Published: December 2008

AbstractOn the basis of a comparison between calculated surface temperature of a physical model and the results from experiments on human subjects it is concluded that the heat loss by radiation and convection plus the uncontrolled evaporation through the skin surface is equal to the heat flow by conductance through the tissues, and the amount of heat given off by evaporation of the regulated sweat secretion is equal to the amount of heat which is transported by the blood stream from the interior to the skin surface. The only regulation necessary for the maintenance of the total heat balance, therefore, is a thermostatic control which can regulate the heat‐transporting blood stream from the interior to the skin surface as well as the secretion of sweat from the glands.
Unitary Components in the Activation of Clarke's Column Neurones
Authors: Eide E. , Fedina L. , Jansen J. , Lundberg A. , Vyklický L. 
Published: December 2008

AbstractIn response to muscle stretch unitary EPSPs were recorded from group I activated dorsal spinocerebellar tract (DSCT) neurones. The size of the different unitary EPSP varied appreciably, the largest was about 5 mV. The rise time and decay times of the unitary EPSPs varied only between 0.2–1 msec and 1–3 msec respectively. The estimate of the number of primary afferent fibres converging on to each second order neurone ranged from 12 to 16. The distribution of amplitudes of individual unitary EPSPs was symmetrical with a coefficient of variation as low as 0.10. This suggests that a large number of quanta are released by each impulse in the primary afferent fibres.
A Dorso‐lateral Spinal Pathway Mediating Information from the Mesencephalon to Dynamic Fusimotor Neurones
Authors: Appelberg B. , Jeneskog T. 
Published: December 2008

AbstractIn cats anesthetized with halothane, the activity of primary muscle spindle afferents from the long digital flexor muscle of the hind limb was recorded. Repetitive electrical stimulation in a restricted part of the mesencephalon in the region of the red nucleus caused a rather selective increase in the sensitivity of the spindles to length changes (dynamic sensitivity). During single shock stimulation in the same region, a response consisting of two positive waves could be recorded in the ventral medulla or in the dorsal part of the lateral funiculus of the spinal cord. By making restricted cord lesions it could be shown that the pathway transmitting the mesen‐cephalic influence to dynamic fusimotor neurones was also located in the dorsal part of the lateral funiculus. The two positive waves were shown to represent activity in rubro‐spinal and cortico‐spinal tracts, the last mentioned being activated by the mesencephalic stimulus via the cerebral cortex. Destruction of rubro‐and cortico‐spinal pathways at a medullary level resulted in the disappearance of the double wave cord response, but did not interfere with the mesencephalic action on dynamic fusimotor neurones. The tract mediating this influence is therefore still unidentified, although its spinal course is now known.
The Effect of Marked Hyperventilation upon Tissue Levels of NADH, Lactate, Pyruvate, Phosphocreatine, and Adenosine Phosphates of Rat Brain
Authors: Granholm L. , Lukjanova L. , Siesjö B. K. 
Published: December 2008

AbstractIn order to study the effect of pronounced hyperventilation upon the redox state of brain tissue rats were hyperventilated with air and measurements were made of the cortical level of NADH, using the microfluorometric method of Chance. Control measurements were made of the tissue concentrations of lactate, pyruvate, ATP, ADP, AMP, and phosphocreatine during and after the hyperventilation. It was found that when the rats were hyperventilated to arterial pCO2 levels below about 20 mm Hg, the NADH fluorescence invariably increased. Although part of this increase may represent a hemodynamic artefact due to a decrease in the tissue blood volume, a large part of it should represent a true reduction in the NADH/NAD+ system. With hyperventilations of this degree there was a proportionally larger increase in lactate than in pyruvate and thus an increased lactate/pyruvate ratio, but there were no changes in phosphocreatine, or in adenosine phosphates, except for a small but significant increase in the AMP concentration. The NADH increase during hyperventilation was slightly decreased when pure oxygen was administered and completely normalized when 3–5 % CO2 was given. The experiments thus strongly suggest an increased reduction in the NADH/NAD+ system of the brain during pronounced hyperventilation.
Nature and Localization of the Sodium Pool during Active Transport in the Isolated Frog Skin
Authors: Zerahn K. 
Published: December 2008

AbstractIn the frog skin epithelium the amount of radio‐sodium originating from the outside solution has been determined under different experimental conditions. It has been found that this sodium‐pool behaves largely as a pool in which the sodium has passed the transport mechanism. It has not been possible under any of the conditions used to demonstrate the existence of epithelial radio‐sodium awaiting active transport. This finding leads to the conclusion that the mechanism for active transport of sodium is effective at the outer surface of the frog skin.