bluuebunny/crossref_metadata_2025_split huggingface dataset:
Production and Distribution of Intracranial and Intraspinal Pressure Changes at Sudden Extradural Fluid Volume Input in Rabbits
Authors: Lindgren Sten , Kinder Lennart 
Published: December 2008

AbstractA device is described for sudden application of a mechanical load to the brain in animals by displacing a column of fluid within a plunger system towards its connection with a hole in the skull. Velocity and displacement of the piston, moving the fluid into the skull cavity, were varied in a series of experiments in rabbits. Simultaneous recordings were made of the pressure pulses produced in the fluid near the parietal site of loading of the brain and at several places within the contents of the skull cavity and spinal canal. By adjusting the fluid input to the skull cavity it was possible to produce intracranial pressure pulses predictable with respect to peak amplitude and duration within a range between 0.1 and 4.0 atm. and one and several hundred msec, respectively. The pressure pulses produced extracranially and in the major part of the skull contents were similar. Simultaneous recordings of the pressure course in the vicinity of the cranio‐spinal junction and in the spinal canal revealed however, that peak amplitude and duration of the pressure pulse then decreased continuously at increasing distance from the site of application of the load. No pressvire changes were found to occur caudally to the level of the fifth cervical vertebra. This method seems suitable for studying the effects of controlled and varied sudden mechanical loading of the brain in animals and the relations between subsequent brief intracranial pressure changes and pathological alterations, similar to those occurring in skull trauma.
Non‐Uniform Blood Flow in the Left Ventricular Wall of Dogs Measured by the Xe‐133 Wash‐out Technique
Authors: Andersen Henning , Bagger Henning , Gotzsche Henning 
Published: December 2008

AbstractIntra‐myocardial injections of Xe‐133 into the left ventricular wall revealed time‐activity curves which indicate that blood flow in the subepicardial layers is 30 % greater than in the subendocardial layers. A two‐compartment model of the ventricular wall was therefore considered, and a good correlation was found between this model and the results of graphical and computer analyses of time‐activity curves obtained by injections of Xe‐133 into the left coronary artery. The flows of these two compartments and flows after superficial and deep intra‐myocardiai injections were not identical. Thus the myocardial two‐compartment model must be abandoned. A gradual decrease of flow from the subepicardial to the subendocardial surface is suggested. If this is true then the wash‐out curve after intra‐coronary injection of Xe‐133 is multi‐exponential and thereby inaccessible to graphical analysis.
Temperature Dependence of Cholinesterase and Lactate Dehydrogenase in the Guinea‐pig, Hedgehog and Codfish
Authors: Johansson Bengt W. 
Published: December 2008

AbstractThe temperature dependence of lactate dehydrogenase (LDH) in brain, heart and skeletal muscle and of acetylcholinesterase (AChE) in brain tissue was investigated in a homeothermic animal (the guinea‐pig), a poikilothermic animal (the codfish) and a hibernator (the hedgehog). The temperature of maxmial LDH activity was higher in the tissues from the guinea‐pig than the other animals (Table I). Similar and more pronounced results were obtained for AChE (Table IV).
Pulmonary Function and G‐Stress during Inhalation of 100 % Oxygen
Authors: Barr P.‐O. , Brismar J. , Rosenhamer G. 
Published: December 2008

AbstractThe effect of 3‐min exposure to 5 G acting in the head to seat direction on arterial oxygen saturation (Sao2) and pH, inspiratory minute volume (VI), end‐tidal Pco2 and heart rate was studied in 8 healthy subjects breathing 100 % oxygen and wearing anti‐G suits. During the first min Sao2 remained unchanged. Thereafter it fell at varying rates in different subjects, the average reduction at the end of the exposure being 6 % (range 0–17 %). Mean VI showed a rapid initial increase by 3 liters/min, remained thereafter essentially unchanged for approximately one min, and increased continuously during the last two min (average final increase 7 liters/min). There were considerable individual differences in the responses of VI. Arterial pH showed a small acidotic shift in all subjects but one (average decrease 0.04 pH units). Average end‐tidal Pco2 fell by 7 mm Hg within the first min and remained then essentially unchanged during the following two min. The arterial oxygen desaturation is attributed to a reduced oxygen content of blood from alveoli with very low V/Q ratios. Individual variability in the responses of VI, end‐tidal Pco2 arterial pH and Sao2 is referred to differences in the G‐induced displacement of blood.
Effect of Reflexes of Somatic Afferents on the Adrenergic Outflow to the Stomach in the Cat
Authors: Jansson Gunnar 
Published: December 2008

AbstractThe adrenergic activity to the stomach in cats anesthetized with chloralose was modified by electric stimulation of somatic afferent nerves. Electric stimulation of “somatic pressor” afferents promptly elicited inhibitory responses of stomach contractions which contractions were, in turn, dependent on cholinergic nervous activity. However, in the absence of such cholinergic activity, corresponding somatic afferent stimulation had only an insignificant effect on the stomach, despite a considerable myogenic activity, suggesting that the inhibitory adrenergic nervous mechanism preferentially operated by interfering with the cholinergic nervous activity.—Activation of “somatic depressor” afferents, on the other hand, suppressed the prevailing supply, if any, of adrenergic nervous activity to the stomach, which could result in augmentation of vagally induced gastric motor responses. Similar effects were obtained also after spinal cord transection indicating that the “somatic depressor” afferents made propriospinal reflex connections with the sympathetic outflow to the stomach.
Conditional Reflex Activation of the Sympathetic Cholinergic Vasodilator Nerves in the Dog
Authors: Bolme Per , Novotny Jozef 
Published: December 2008

AbstractSympathetic, cholinergic kasodilatation in skeletal muscle was induced as orienting and conditional reflex responses in conscious dogs. A sound stimulus elicited an orienting reflex accompanied by an atropine‐sensitive vasodilatation in the skeletal muscles of the hind limb. Further, a tachycardia and a slight blood pressure rise were noticed. The orienting reflex response disappeared gradually on repetition of the sound stimulus. The same cardiovascular events were obtained as conditional reflexes to both electrical cutaneous stimulation and exercise on a treadmill. The conditional responses were not diminished if the conditional reflexes were reinforced by training. Graded conditional responses were obtained when the intensities of the unconditional stimuli were varied. The increase in blood flow to the hind limb following treadmill exercise was not influenced by atropine. Our findings indicate that the sympathetic vasodilator system is activated prior to situations when an increased muscle blood flow is suddenly required. The results also suggest that activation of the dilator nerves takes place not only in emotionally charged situations, such as the defence reaction, but also in anticipation of exercise when the emotional involvement is less prominent.
Reciprocal Control of Spontaneous Activity and Reflex Effects in Static and Dynamic Flexor γ‐motoneurones Revealed by an Injection of DOPA
Authors: Bergmans J. , Grillner S. 
Published: December 2008

AbstractSingle γ‐efferents to flexors have been studied in the spinal unanesthetized cat before and after an intravenous injection of DOPA. The γ‐efferents could be classified in two groups, one with a high level of spontaneous activity that was decreased after an injection of DOPA, and another with a low level of activity that was enhanced after DOPA. These data together with differences in reflex behaviour between the two types of γ‐motoneurones provided a basis for a comparison with the deduced properties of dynamic and static γ‐motoneurones obtained from studies of spindle afferents with primary and secondary endings. It could be concluded that the former type is identical with dynamic and the latter with static γ‐motoneurones. Both dynamic and static neurones could be reflexly activated in the long‐latency flexor reflex occurring after DOPA. Likewise both types of γ‐motoneurones were activated in the short‐latency flexor reflex, the dynamic more effectively before and the static more effectively after DOPA. The results suggest that descending noradrenergic fibres control reflex activation and the spontaneous activity of γ‐motoneurones to flexors in a reciprocal fashion.
Properties of Clarke's Column Neurones
Authors: Eide E. , Fedina L. , Jansen J. , Lundberg A. , Vyklický L. 
Published: December 2008

AbstractMechanisms responsible for the high efficacy of synaptic actkation of the dorsal spinocerebellar tract (DSCT) was investigated with intracellular recording from Clarke's column cells in anesthetized spinal cats. The spike potential is brief (mean duration 0.57 msec) and followed by a delayed depolarization. Our observations suggest a high safety for impulse transmission from the initial segment to the soma and from the soma to the dendrites. The afterhyperpolarization is small (<2 mV), shortlasting (30–50 msec) and has a high sensitivity to hyperpolarizing currents. There is only a small conductance change during the afterhyperpolarization. The monosynaptic group I EPSP has a mono‐exponential decay, the time course of which is explained by the passive properties of the membrane. It is postulated that the transmitter action is brief. Possible mechanisms for multiple discharges evoked by group I volleys in DSCT cells are discussed. Injected currents evoke maintained firing and within a wide range there is a linear relation between frequency and current strength (mean slope constant 4.8 imp/sec/mV). Depolarization produced by muscle stretch and injected current have equivalent effect on the firing rate. The properties of DSCT cells seem well adapted to their function to transfer sensory signals and operate over a wide frequency range
Elicitation of Reflex Vagal Relaxation of the Stomach from Pharynx and Esophagus in the Cat
Authors: Abrahamsson H. , Jansson G. 
Published: December 2008

AbstractDistension of different parts of the esophagus in chloralosed cats caused prompt and pronounced relaxation of the stomach. Even slight distension was sufficient to elicit gastric relaxation, and the degree of relaxation vaned with that of the esophageal distension. The gastric relaxatory response was shown to be due to elicitation of a vago‐vagal reflex to the stomach. The response could be elicited also after exclusion of spinal connections, but disappeared after vagotomy. It could not be blocked by atropine or guanethidine. It thus resembled the gastric relaxation obtained by direct electric stimulation of the vagal “relaxatory” fibres to the stomach. It is concluded that these fibres constitute the efferent pathway of the observed esophageo‐gastric vago‐vagal relaxatory reflex.—Furthermore, a similar gastric relaxation, mediated via the vagal efferent relaxatory fibres, was recorded in connection with pharyngeally elicited swallowing. It is assumed that the gastric relaxation pattern described plays an essential role in “receptive relaxation” of the stomach during deglutition.
Changes in the Activity of Isolated Vascular Smooth Muscle in Response to Reduced Osmolarity
Authors: Jonsson Olof 
Published: December 2008

AbstractThe effects of hypo‐osmolarity on the spontaneous activity of the smooth muscle in the isolated portal vein of the rat have been studied in solutions with varied ionic composition. A comparison between the stimulatory effects of lowered osmolarity and increased [K+]o indicated that at normal [K+]o in the control state the excitation caused by hypotonicity is not mediated only via changes in the [K+]i/[K+]o ratio. The response to hypo‐osmolarity at a higher extracellular potassium concentration is, however, more readily explained by the change in [K+]i/[K+]o which occurs in association with the swelling of the cells. This might be attributed to the fact that the membrane potential of smooth muscle is more dependent on the transmembrane concentration gradient for potassium at higher levels of external potassium concentrations.The stimulatory effects of hypo‐osmolarity are markedly reduced at a low [Na+]o but are not considerably affected by comparable reductions in [K+]o or [Cl+]o. This indicates that the transmembrane sodium ion gradient is involved in the mechanisms by which hypo‐osmolarity excites the spontaneous activity of vascular smooth muscle. One possible interpretation is that the swelling of the muscle cells in hypotonic solutions causes an increase in the permeability of the cell membrane to the relatively larger sodium ion.
Local Transmitter Concentrations in Vascular Smooth Muscle during Vasoconstrictor Nerve Activity
Authors: Ljung Bengt 
Published: December 2008

AbstractAdrenergic excitatory responses of a nerve‐muscle preparation consisting of the rat portal vein and its sympathetic post‐ganglionic nerve supply were studied quantitativelyin vitro.The maximal contractile response to nerve stimulation was obtained at 16 imp/sec and it averaged 56 per cent of the maximal response to exogenous noradrenaline, NA, (10–4M).Factors such as the myogenic propagation between the individual muscle cells and the sparse distribution of the sympathetic nerve fibres do not allow an estimation of the transmitter concentration during nerve activity from a mere comparison of the magnitude of the responses to nerve stimulation and to exogenous NA, respectively. It was shown, however, that the degree of reduction of the contractions induced by exogenous NA, after partial a‐receptor blockade by phenoxybenzamine, was inversely related to the concentration of NA in the bath. By comparing the reductions of the neural responses with the reductions of the responses to graded concentrations of exogenous NA the effective transmitter concentration could be estimated. The values obtained were (8 ± 4) × 10–6M at 4 imp/sec and (2 ± 0.5) × 1‐‐5M at 16 imp/sec.The effectiveness of a‐adrenergic blocking agents in affecting neural and humoral responses to catecholaminesin vivois discussed in the light of the present findings.
Reflex Responses Induced by Stimulation of Hypoglossal Afferents
Authors: Lindquist Chr. , Mårtensson A. 
Published: December 2008

AbstractOn stimulation of the central end of the cut hypoglossal nerve, multisynaptic reflex discharges were set up in the intrinsic laryngeal muscles and in certain muscles innervated by the facial nerve; by contrast, reflex responses were never observed in tongue muscles. Activation of the fibers mediating the reflex responses required a stimulus strength 2–4 times that required for activation of the hypoglossal motor fibers. On the basis of earlier data on the caliber spectrum of the hypoglossal nerve fibers and on the relation between the threshold values for afferent fibers and motor fibers it is concluded that the hypoglossal afferents belong to the group III fibers. The threshold differences also eliminate the possibility of the centrally relayed responses being set up by activation of recurrent collaterals from hypoglossal alpha motor fibers.—The possibility that synchronized impulses in the hypoglossal afferents might depolarize central afferent terminals in other nerves to firing level and thus open up reflex connections not operative under physiological conditions is considered and excluded.—The rypes of receptors connected to the high‐threshold hypoglossal afferents and their functional role are briefly discussed.
The Accumulation of Albumin‐125I and Thyroxine‐131I in Wounds
Authors: Funch‐Rosenberg Hans , Hansen Heinz J. M. , Moltke Erik 
Published: December 2008

AbstractThe distribution of 125I‐labelled guinea‐pig albumin and 131I‐thyroxine in skin and wounds of guinea pigs has been investigated in the period 1–72 hrs after the simultaneous injection of the radioactive compounds. The relative amounts of labelled thyroxine and albumin in normal skin and skin‐wounds, old as well as fresh, indicate that these tissues accumulate thyroxine in excess of that brought there on plasma‐proteins; furthermore that the thyroxine accumulation increases in fresh wounds during the experimental period.
Effects of Puromycin and Luteinizing Hormone on the Uptake of 3‐O‐Methylglucose by the Isolated Rat Ovary
Authors: Ahrén Kurt , Hamberger Lars 
Published: December 2008

AbstractThe rate of uptake of the non‐utilizable monosaccharide 3‐O‐methylglucose was studied in isolated ovaries from prepubertal rats. It was found that puromycin, added to the incubation medium in a concentration which completely blocked the protein synthesis, markedly decreased the rate of uptake of 3‐O‐methylglucose. It was also found that addition of luteinizing hormone (LH) to the incubation medium still increased the rate of uptake of 3‐O‐methylglucose when the protein synthesis was blocked by puromycin.
The Mechanism of the Increased Maximum Work Performance of Small Muscle Groups Resulting from “Diverting Work” with Other Muscle Groups
Authors: Alpert J. S. 
Published: December 2008

AbstractThe mechanism of increased work performance resulting from “diverting works” was examined. Muscle blood flow was measured in exercised and rested muscles by means of venous occlusion plethysmography and 133Xe clearance. Measurements of muscle blood flow, blood pressure and work performance following “diverting work” and other stimuli were compared with values obtained during control rest periods. Stimuli which caused a substantial rise in arterial blood pressure (“diverting work”, change in heart level, pain) caused increases in blood flow and work performance in exercised muscles. Non‐pressor or mild pressor stimuli (non‐strenuous “diverting work”, CO2 inhalation, apnea, cold) resulted in unchanged blood flow and work values in the exercised muscles. It is concluded that pressor stimuli produce increased muscle blood flow in maximally ischemic muscles due to release of muscle arteries from neurogenic and myogenic control. The increased muscle blood flow during periods employing pressor stimuli results in improved muscle restitution and hence increased work performances.
Demonstration of Adrenergic Receptor Function and Innervation in the Ductus Arteriosus of the Human Fetus
Authors: Borëus L. O. , Malmfors T. , McMurphy D. M. , Olson L. 
Published: December 2008

AbstractAdrenergic receptor function in the human ductus arteriosus has been demonstrated by in vitro perfusion and spiral strip experiments and correlated with the finding of specific adrenergic nerve fibers in the smooth muscle layer of the media by histochemical fluorescence technique. The results support the possible role of an adrenergic mechanism involved in the closure of the ductus in neonates.
Oxygen Uptake in Skeletal Muscle of the Anesthetized Dog during Sympathetic Vasodilatation
Authors: Bolme Per , Novotný Jozef 
Published: December 2008

AbstractOxygen uptake in dog skeletal muscle was studied upon activation of the sympathetic cholinergic vasodilator nerves, upon reflex inhibition of the peripheral vasoconstrictor nervous tone and as a response to i.a. acetylcholine infusion. Oxygen uptake was calculated from the arteriovenous oxygen saturation and the blood flow. Stimulation of the hypothalamic vasodilator area or of the sympathetic lumbar chain, after adrenergic nervous blockade, produced an increased blood flow and a rise in calculated oxygen uptake in the muscle. In most animals the oxygen uptake returned to, or went slightly below, pre‐stimulatory levels after an initial increase for about 30 sec. However, in some experiments the oxygen uptake was elevated during the whole period of vasodilatation. Reflex inhibition of vasoconstrictor tone was produced in crosscirculation experiments by stimulating the carotid sinus nerve of the recipient dog. When the stimulation resulted in a blood flow rise in the cross‐circulated muscle, the oxygen uptake in the muscle remained increased during the whole period of vasodilatation. Acetylcholine was infused i.a. to produce vasodilatations comparable to those induced by vasodilator nerve stimulation or reflex inhibition of vasoconstrictor tone. A blood flow rise was accompanied by an initial brief inctease of the oxygen uptake followed by a return to resting values. It is concluded that sympathetic cholinergic nervous stimulation and acetylcholine elicit changes in the oxygen uptake in skeletal muscle indicating an effect predominantly on precapillary resistance vessels and not, or to a much lesser extent, on precapillary sphincters. In contrast, by inhibition of vasoconstrictor nervous tone both precapillary resistance vessels and precapillary sphincters are dilated.
Subcellular Distribution of3H‐noradrenaline in Adrenergic Nerves of Mouse Atrium — Effect of Reserpine, Monoamine Oxidase and Tyrosine Hydroxylase Inhibition
Authors: Jonsson Gosta , Sachs Charlotte 
Published: December 2008

AbstractThe subcellular distribution of exogenously administered3H‐noradrenaline in adrenergic nerves of mouse atria after pretreatment with nialamide, reserpine and nialamide, or the methylester ofa‐methyl‐p‐tyrosine (H44/68) has been investigated. Parallel fluorescence histochemical studies have been performed. Both reserpine and H44/68 cause a pronounced decrease in the endogenous noradrenaline stores. The subcellular distribution was practically identical in untreated, nialamide‐pretreated and H44/68‐pretreated animals; approximately 30%3H‐noradrenaline was recovered in the particulate fraction which in all probability contains the amine storage granules. In the reserpine‐nialamide pretreated mice, however, most of the3H‐noradrenaline was found in the supernatant iraction, and about 10 % in the particulate fraction. These studies thus confirm earlier investigations that reserpine is a potent inhibitor of the noradrenaline uptake in the amine storage granules, although there is a small reserpineresistant uptake. Furthermore, after tyrosine hydroxylase inhibition both the ‘membrane pump’ and the granular uptake mechanism seem to operate. The morphological studies disclosed differences in the adrenergic nerves when the noradrenaline taken up is mainly granularly or extragranularly stored, since the varicosities are in the former case distinct and the latter case less distinct, while the pre‐terminals are more prominent. Methodological studies of the homogenization procedure for subcellular distribution studies have also been performed, the results of which are discussed in view of the experimental data obtained.It is now well established, based on both biochemical and electronmicroscopic evidence. that the peripheral adrenergic transmitter NAIis mainly stored in special intraneuronal storage granules (Euler and Hillarp 1956. Schümann 1958. Camps and Shideman 1962. Potter and Axelrod 1962, Lundborg 1967, Hokfelt 1969). Exogenously administered NA is rapidly taken up by the axonal membrane of the adrenergic neuron and subsequently incorporated into the storage granules, mainly by means of an ATP‐Mg++‐dependent uptake mechanism. This latter process can be efficiently‐blocked by reserpine (Carlssonet al.1963, Euler and Lishajko 1963.