bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Exercise on the Development of Collateral Circulation after Experimental Occlusion of the Femoral Artery in the Cat
Authors: Sanne H. , Sivertsson R.
Published: December 2008

Flow resistance in the collateral vessels passing an occlusion of the femoral artery was determined 5 weeks after the occlusion in 24 cats kept in small cages and 21 cats trained daily on a treadmill. The collateral resistance was determined at maximal vasodilatation to reveal whether a structural outgrowth had taken place. Despite the occurrence of a pronounced “spontaneous” outgrowth of the colalteral vessels, it could be shwon that collateral resistance was 30 per cent less in the trained group. This difference was statistically highly significant (0.01>p>0.001). On the other hand, flow resistance in the vascular bed, distal to the occlusion, did not change after the arterial occlusion and was not affected by training
Hemodynamics of the Bone Marrow Circulation
Authors: Michelsen Kåre
Published: December 2008

In 44 anesthetized rabbits the femur was perfused in situ through the nutrient artery by blood led through an extracorporal perfusion arrangement from the left carotid artery. Blood inflow, perfusion pressure and intramedullary venous pressure were recorded. At perfusion pressures of 110 to 150 cm of saline (80 to 110 mm of Hg) blood flow in the different animals ranged from 0.1 to 1.2 ml/minXg wet marrow tissue, and intramedullary venous pressure from 10 to 80 cm of saline (7 to 60 mm of Hg). Flow and intramedullary venous pressure both increased with the perfusion pressure whereas flow decreased and intramedullary venous pressure increased when the venous pressure outside the bone increased, showing that in the bone marrow both an arterial and a venous resistance were present. The predominant effect of noradrenaline was to constrict, and of acetylcholine to dilate arterial vessels. No reactive hyperemia could be demonstrated upon occlusion of the arterial inflow. The arterial vessel showed only a weak ability to autoregulate flow. The venous resistance varied greatly from one preparation to another, differing from only a small fraction of‐to more than half the total vascular resistance in the bone marrow. It stayed constant or increased with increasing perfusion pressure, thereby causing the pressure‐flow relationship curves to differ from convex against the pressure‐ to convex against the flow axis. The hemodynamic properties demonstrated were explained as being due to the unusual vascular anatomy and the rigid enclosement of the bone marrow
Fecal Sterols in Infants Bile Acids and Steroids 194
Authors: Gustafsson J.‐Å. , Werner B.
Published: December 2008

The predominant sterols in feces of 31 infants have been studied by gas‐liquid chromatogaphy and gas chromatography‐mass spectrometry. Cholesterol, β‐sitosterol, and campesterol were the predominant sterols in feces of infants under one year of age. At about the age of 1 year, coprostanol began to appear in feces; after this tiem the predominant fecal sterols were coprostanol, cholesterol, campesterol, 24a‐ethylcoprostanol, and β‐sitosterol. The sterol pattern of feces of infants from 5 months of age up to the highest age investigated (1 year and 9 months), however, was characterized by considerable individual variation
Postexcitatory Depression of Gustatory Receptors
Authors: Hellekant Göran
Published: December 2008

It was observed that when the same sapid solution was applied two or more times to the tongue of the cat, the first exposure depressed following responses although the tongue was continuously rinsed with water between the periods of stimulation. This depression vanished gradually but was noticeable after some substances even after one min of water rinse. The time course of the depression depended on the chemical and its concentration, but seemed to be unaffected a) by changes in temperature (27–40°C), b) by the duration of stimulation (3–10 sec) and c) the flow rates of the water rinse (1.7–5 ml/sec).
Exercise and Arterial Pressure during Simulated Increase of Gravity
Authors: Linnarsson D. , Rosenhamer G.
Published: December 2008

Heart rate and arterial pressure were continuously recorded in eight healthy young adults in the sitting position at 3 G, acting in the head‐seat direction, before and during leg exercise at 600 kpm/min for 6 min. In spite of the threefold increase of the hydrostatic pressure gradient along the head‐trunk line the arterial mean pressure at the level of the heart was higher at 3 G than at normal gravity, both at rest and during exercise. Exercise at 3 G resulted in a more rapid rise in the arterial mean and pulse pressures, the final increments being similar or somewhat greater than they were at normal gravity. The results emphasize the importance of the leg muscle pump as a booster of the cardiac pump in situations where large hydrostatic pressures in the lower portion of the body would otherwise tend to curtail the effective circulating blood volume.
Effect of Direct Current on the Responses to Colored Flashes of Single Cells in Monkey Cortex
Authors: Guld Christian , Lennox‐Buchthal Margaret
Published: December 2008

In monkeys the response to monochromatic flashes was recorded of single units in the cortex corresponding to within 1–2° from the fovea. All units which responded selectively to blue, to green or to red flashes did so in an on fashion.

Direct currents were applied through the tip of the recording microelectrode. The effects of currents were those to be expected of jntracellular electrodes. Smaller polarizing currents than those exciting the cell directly affected the response to light. This effect was related to the cell's spectral sensitivity. The response of red‐sensitive cells was decreased by depolarizing currents but polarizing currents did not change the response of green‐sensitive units. The conclusion is that red‐ and green‐sensitive units have a specific synaptic organization in the cortex. Units responding to all colors were affected by polarizing currents in the way to be expected, i.e. their response was increased by depolarizing and decreased by hyperpolarizing currents. The response of blue‐sensitive units was affected variously.
Muscle Spindle Responses to Concomitant Variations in Length and in Fusimotor Activation1
Authors: Lennerstrand Gunnar , Thoden Uwe
Published: December 2008

The capability of the different fusimotor fibres to mediate the governing signals in the proposed ‘follow‐up length’ servo regulation of muscle movements can be judged from the responses of spindle endings to increasing rates of fusimotor fibre stimulation concomitant with passive muscle shortening. Spindle endings in the ankle and the intercostal muscles have been studied. Dynamic and static fusimotor fibres have been stimulated in isolation or in combinations. Length and fusimotor inputs have been modulated in triangular waves, mostly of equal periodicity. For a servo action the afferent impulse frequency should be able to increase in pace with increasing fusimotor drive in spite of concomitant length decrements. Most of the static fibres, but none of the dynamic fibres, could induce an acceleration of the spindle discharge over the physiological range of length changes. This ability of the static fibres was not affected by the co‐activation of a dynamic fibre either with varying rates or with constant rate of stimulation, but when the activation by another static fibre was added, the increase in impulse rate was sometimes transformed into a decline. Some static fibres, most of which had type II effects on the position sensitivity, showed little ability to perform servo action as defined above. Other functional implications of the results are also discussed.
Aortic Baroreceptor Activity during Permanent Distension of the Receptor Area
Authors: Aars Harald
Published: December 2008

Aortic 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

The 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

The 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

Endosomatic 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.
Effect of the Left Atrial Pressure on Vagal Afferent Discharge from the Left Atrium, and on the Sympathetic Postganglionic Discharge to the Heart
Authors: Hakumäki M. O. K.
Published: December 2008

A linear correlation has been found between the pressure impulse of the v‐wave of the left atrium, and the number of B‐type vagal afferent impulses from the left atrium, both within the fractions of one cycle, and in the different successive cycles. A positive inverse correlation exists between the ratio of the number of B and A impulses, and the number of sympathetic postganglionic impulses.
Metabolism of Dopamine and Noradrenaline in Normal, Atrophied and Postganglionically Sympathec‐ tomized Rat Salivary Glands in vitro
Authors: Jonason Jan
Published: December 2008

Slices 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

An 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

Purified 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

A 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

Pancreatic 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

The 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

The 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

The 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

No 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

In 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

It 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

On 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

In 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

In 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

In 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

In 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.
Permeability Characteristics of Vascular Smooth Muscle Cells as Revealed by Their Osmotic Responses to Non‐Electrolytes
Authors: Johansson Borje
Published: December 2008

Changes of cell volume in the smooth muscle of the isolated rat portal vein, produced by variations in extracellular osmolarity, are associated with characteristic changes in the spontaneous electrical and mechanical activity of the preparation (Johansson and Jonsson 1968, Arvill, Johansson and Jonsson 1969). An analysis of such responses to anisosmotic solutions containing different non‐electrolytes was carried out in the present study in order to elucidate the osmotic influences of the test substances on the vascular smooth muscle cells. The time course of the responses revealed the following relative rates of penetration through the cell membranes: sucrose < erythritol < glycerol < urea < thiourea < ethylene glycol = propylene glycol = tetramethylene glycol = pentamethylene glycol = urethane. The importance of molecular size and lipid solubility for this order of permeability is discussed. A quantitative analysis of responses to solutions containing urea gave an approximate estimation of the osmotic reflexion coefficient for this substance. The value obtained was 0.65 which corresponds to an equivalent pore radius of 3.7 Å. This information and previous data concerning the uptake of urea‐14C by the rat portal vein could be used for a calculation of the total pore area. The result indicated that the pores occupy only a very small fraction, 7 × 10–7, of the total area of the cell membrane and that the number of pores is of the order of 103 per cell or 1.6 × 103 per cm2.
Effect of Acid in the Duodenal Bulb on Gastric Secretory Responses to Sham Feeding1
Authors: Nilsson Göran
Published: December 2008

Gastric secretion was stimulated by sham feeding in Pavlov pouch dogs with esophageal fistulae and isolated pouches of the duodenal bulb. Reduction of the intrabulbar pH to pH 3–4 inhibited the acid response to sham feeding. Bulbar acidification was more effective in inhibiting acid responses to 1 and 10 min of sham feeding than responses to 30 min of sham feeding. Short periods of bulbar acidification were sufficient to activate the bulbar inhibitory mechanism.
Uptake and Distribution of Rubidium‐86 and Potassium‐43 in Mice and Rats—an Autoradiographic Study
Authors: Olsson Kurt A. , Söremark Rune , Wing Kenneth R.
Published: December 2008

The uptake and distribution in mice of rubidium‐86 (86Rb) and potassium‐43 (43K) was studied using whole body autoradiographic techniques. In addition, a microautoradiographic study of the distribution of 86Rb in the heads of rats was made. The results demonstrate high relative accumulation of 86Rb in hyaline and articular cartilage, tendon, forming bone, liver, pancreas, salivary glands, thymus, spleen and skeletal muscle. At one hour post‐injection, the distribution pattern of 43SK was similar to but much less differentiated than that of 86Rb. Relatke to the accumulation of each in skeletal muscle, 86Rb was more concentrated than 43K in hyaline and articular cartilage, tendon and liver, while the converse was seen in heart muscle, lung, bone and brain. The micro‐autoradiograms demonstrated high relative uptake of 86Rb in trahecular bone and the dentin and enamel of unerupted teeth. The results of the present study have been compared to those of previously published quantitative studies on the accumulation of 86Rb and 42K, and the results were found to be in close agreement. In addition, the present results demonstrate high relative accumulation of 86Rh and 48SK in hyaline and articular cartilage, tendon and forming bone, and high 86Rb concentrations in forming teeth and foetal bone and cartilage, observations which hale not been made in earlier studies. The similarities to and differences from the results of a similar study of the uptake and distribution of caesium‐137 (137Cs) are discussed.
Hair Discs and Pacinian Corpuscles Functionally Associated with the Carpal Tactile Hairs in the Cat
Authors: Nilsson Bengt Y.
Published: December 2008

A hair disc containing Merkel cell‐neurite complexes at the base of the epidermis lateral to each carpal sinus hair in the cat is demonstrated. The physiological properties of these receptors and of the Pacinian corpuscles around the sinus hair root were analyzed using electro‐physiological techniques and a mechanical stimulator permitting displacements at different rates and amplitudes. The hair disc receptor could be excited by direct mechanical stimuli and by lateral deflection of the hair. The dynamic response was displacement‐rate sensitive. The slowly adapting static response was related to the displacement amplitude. The Pacinian corpuscles followed a sinusoidal skin stimulation from 20 c/s to 300–400 cis. A plot of the lowest amplitude giving one imp/cycle at different frequencies gave a U‐shaped curve with lowest threshold at 125–250 c/s. These receptors were also sensitive to vibratory stimulation of the hairs; on rapid hair displacement on and off responses resulted. An example is given of simultaneous activation of slowly adapting hair receptors and Pacinian corpuscles by displacement of a hair. The functional significance of the unique combination of four different types of mechanoreceptor in “the tactile hair organ” is discussed.
Respiratory Sensitivity to Acute Hypoxia in Goat Kids Born at High Altitude
Authors: Mines Allan H. , Sørensen Søren C.
Published: December 2008

In human infants, chronic hypoxia irreversibly desensitizes the peripheral chemoreceptor respiratory response to acute hypoxia. We attempted to desensitize 2 goat kids conceived at sea level, delivered after 1 to 3 weeks at 3100 m altitude, and transferred to 3800 m at 6 weeks of age. The kids were brought to sea level when 14 weeks old. The respiratory response to GO, at two levels of oxygen tension was determined 6 to 8 weeks later. The slope of the CO2‐response curve at high PO2 (200 mm Hg) and the change in slope and fall in PCO2 intercept produced by hypoxia (PAO2= 40 mm Hg) resembled those of normal adult goats, indicating no permanent desensitization.
Mast Cells and 5‐HT. Intracellular Release of 5‐Hydroxytryptamine (5‐HT) from Storage Granules during Anaphylaxis or Treatment with Compound 48/80
Authors: Carlsson S.‐A. , Ritzén M.
Published: December 2008

The release of 5‐hydroxytryptamine (5‐HT) and granules from peritoneal mast cells during in vitro and in vivo anaphylaxis and after treatment with compound 48/80 in vitro was investigated by quantitative cytochemical methods. Sensitization was achieved by s.c. injections of horse serum with H. pertussis, and anaphylaxis was observed 3–30 weeks later. The 5‐HT content of mast cells was assayed by microfluorimetry, the cellular content of granules by microinterferometric measurements of cellular dry mass. Incubation of peritoneal mast cells with antigen in vitro resulted in release of 7–32% of 5‐HT, compared to 20–50% release following i.v. injection of specific antigen to the same rat. Incubation of non‐sensitized mast cells with compound 48/80 (1.6 μg/ml) caused a release of 45% of the 5‐HT. Microfluorimetric and microinterferometric measurements of the same individual mast cells revealed a proportionally greater release of 5‐HT than lowering of dry mass values. Since only a small part of the cytoplasmic dry mass is non‐granular material, the results indicate that under the present experimental conditions about 40% of the total 5‐HT release was not accompanied by a simultaneous extrusion of granules. It could also be demonstrated by fluorescence microscopy that a varying proportion of the granules had released their 5‐HT while still intracellularly located. This demonstration of intracelular release of 5‐HT from storage granules may be relevant also for other types of secretory cells.
Histochemical Characterization of a Tryptamine‐Like Substance Stored in Cells of the Mammalian Adenohypophysis
Authors: Björklund Anders , Falck Bengt
Published: December 2008

A recently developed, sensitive fluorescence method for the histochemical localization and the microspectrofluorimetric characterization of tryptamine (Björklund, Falck and HBkanson 1968) has been applied to the pituitary gland of the rat, cat, and pig. In all three species, most of the cells of the pars intermedia and many cells in the pars distalis were found to store a substance in the cytoplasm that could be transformed to a highly fluorescent derivative under the special reaction conditions required to obtain a high fluorescence yield of tryptamine. This pituitary fluorophore, moreover, showed the same microspectrofluorimetric characteristics under various conditions as does the tryptamine fluorophore. These histochemical and microspectrofluorimetrc characteristics differ clearly from those exhibited by a number of catechol and indole compounds, including the biogenic catecholamines, 5‐hydroxytryptamine and tryptophan. The reliability and the significance of the histochemical criteria are discussed, and it is concluded that there is much to support the view that tryptamine, or a closely related β(3–1ndolyl)ethylamine, is stored in the adenohypophysis. Another fluorophore that may derive from a hitherto unknown biogenic phenylethylamine was disclosed in a large number of pars distalis cells not identical with those that possibly store tryptamine.
The Influence of DOPA on the Static and the Dynamic Fusimotor Activity to the Triceps Surae of the Spinal Cat
Authors: Grillner S.
Published: December 2008

The influence of descending “noradrenergic” fibres on the stretch reflex and the discharge of γ‐motoneurones to the triceps surae has been analysed by injecting DOPA i.v. in the acute spinal unanesthetized cat. After DOPA, a tonic stretch reflex develops in the soleus muscle as revealed by an increased electromyographical activity on extension of the muscle. In parallel, static γ‐motoneurones aqcuire a resting discharge, which can be inferred from the finding that secondary endings have an elevated discharge rate after DOPA. The discharge in single γ‐efferents could be influenced through short latency reflex paths from afferent fibres including group II afferents; further, the γ‐efferents were found to participate in the late and long‐lasting reflex effects that can be evoked after DOPA. On the basis of their resting discharge and reflex effects, the γ‐efferents recorded could tentatively be identified as static or dynamic. Both static and dynamic γ‐motoneurones to extensors have a higher resting discharge after DOPA. Hence in contrast to previous findings on flexor γ‐motoneurones no reciprocal control on the resting discharge in the two types of efferents is exerted. Only γ‐motoneurones classified as static received monosynaptic activation from fast descending fibres, presumably vestihulospinal.
Intracellular Potentials of the Corneal Epithelium
Authors: Ehlers Niels
Published: December 2008

Ehlers, N. Intracellular potentials of the corneal epithelium. Acta physiol. scand. 1970. 78. 471–477.

The potential and resistance profiles through the rabbit and cat corneal epithelium were studied by means of microelectrodes. Negative intracellular potentials were recorded in all experiments. A transepithelial potential difference was regularly found only in rabbits, the inside being 10–15 mV positive in relation to the outside. Positively directed peaks were recorded inside the epithelium, which reached but never exceeded the level of the inside potential. The number of these peaks increased when epithelial oedema was produced by increasing the transcorneal hydrostatic pressure difference. In consequence, the peaks are believed to represent intercellular spaces. The electrode resistance was measured continuously and simultaneous with the potential. During penetration of the cytoplasm the resistance was about twice as high as in the bathing fluid, it increased further when cellular membranes were punctured, and especially when the basement membrane was penetrated.
Characteristics of Receptors and Afferent Fibres of the Forelimb Interosseous Nerve of the Cat
Authors: Silfvenius H.
Published: December 2008

Silfvenius, H. Characteristics of receptors and afferent fibres of the forelimb interosseous nerve of the cat. Acta physiol. scand. 1970. 79. 6–23.

A description is given for dissection and identification of the forelimb interosseous nerve, Int. f., a branch of the median nerve. The nerve contained on average 225 axons. The measured diameters of the myelinated axons of the Int. f. ranged between 1 and 16 μ. A bimodal distribution of fibres was found, with peaks around 4 μ and 10 μ. The fibres of the low threshold main component of the compound action potential conducted at velocities between 85 and 110 m per sec. The properties of receptors and afferent fibres were studied in 52 single fibres of the median nerve. About 50 per cent of these were rapidly adapting, the others slowly adapting. Among the rapidly adapting, 33 per cent were low threshold vibration sensitive Pacinian receptors whose fibres conducted at velocities between 63 and 117m per sec. The remaining 15 per cent were identified as high threshold tap receptors, some of which were vibration sensitive. Their fibres conducted at velocities between 27 and 118 m per sec. 36 per cent of the slowly adapting units were tension receptors with fibres conducting at velocities between 27 and 110 m per sec. The other group (12 per cent) consisted of muscle spindles. They conducted at velocities between 85 and 110 m per sec. About 4 per cent of the population remained unidentified. Functional aspects of the findings are discussed.
Pregnancy in Exercised and Food Restricted Goldthioglucose Obese Mice
Authors: Einer‐Jensen N. , Larsson S. , Nielsen P. Alstrup , Secher N. J.
Published: December 2008

Einer‐Jensen, N., S. Larsson, P. Alstrup Nielsen and N. J. Secher. Pregnancy in exercised and food restricted goldthioglucose obese mice. Acta physiol. scand. 1970. 79. 5a‐63.

NMRI/BOM mice made obese with goldthioglucose were studied with respect to the influence of forced muscular exercise and food restriction upon fertility. The obese mice were found to be sterile. Only minor disturbances were observed in the vaginal smears. After exercise and food restriction resulting in pronounced decrease in weight they became fertile and gave birth to normal litten.
Effect of Nicotinic Acid on ACTH and Noradrenaline Stimulated Lipolysis in the Rabbit. I. In Vivo Studies
Authors: Boberg Jonas , Micheli Horace , Rammer Lennart
Published: December 2008

ACTH, 50, 10, 2 and 0.5 IU/kg b.w. and noradrenaline, 1.0 μg/kg/min were given i.v. to fed, unanesthetized rabbits either pretreated with nicotinic acid or not.

Both ACTH and noradrenaline increased arterial concentration of free fatty acids (FFA). For noradrenaline this effect was present only in rabbits with lower body weight and furthermore the effect was less pronounced and of shorter duration than for ACTH.

Nicotinic acid inhibited partly the increase of plasma FFA caused by 0.5 IU of ACTH but not that after the higher doses. Nicotinic acid had sometimes but not always an inhibitory effect on the increase caused by noradrenaline while nicotinic acid by itself did not change the basal levels of plasma FFA.
Effect of Nicotinic Acid on ACTH and Noradrenaline Stimulated Lipolysis in the Rabbit. II. In Vitro Studies Including Comparison with Prostaglandin E1
Authors: Boberg Jonas , Micheli Horace , Rammer Lennart
Published: December 2008

Perirenal adipose tissue from male rabbits was inrubated in vitro and the glycerol release followed as a measure of lipolysis. Addition of nicotinic acid to the medium did not change the basal release. Nicotinic acid inhibited the noradrenaline stimulated lipolysis only in 3 of 8 rabbits, while PGE, under the same conditions was inhibitory in 6 of 6 rabbits. Nicotinic acid only inhibited lipolysis stimulated by ACTH at low doses in one of seven experiments. In comparison to PGE, nicotinic acid was found to be a weaker inhibitor of lipolysis in rabbit adipose tissue stimulated in various ways in vitro. These findings suggest that the previously seen weak properties of nicotinic acid as a FFA lowering compound in rabbits may be explained by factors within adipose tissue.