bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cerebral Units Activated by Tactile Stimuli via a Ventral Spinal Pathway in Monkeys
Authors: Anderson Sven A. , Finger Stanley , Norrsell Ulf 
Published: December 2008

AbstractExtracellular microelectrode recordings were made in the forelimb and/or hindlimb areas of the cerebral post‐central gyri of 7 monkeys before and/or after acute dorsal hemisections of the cervical or low thoracic spinal cord. The animals were anaesthetized with either pentobarbitone sodium or chloralose. Among the units which were encountered after the lesions were 114 which could be influenced from the periphery. 38 units discharged to light tactile stimulation of small receptive fields and had a topographical organization like that observed in the intact animal. The remaining 76 units could be activated by peripheral electrical stimulation and/or by tapping, squeezing or light pinching. No units were found which specifically were activated by noxious stimuli. The two groups of cortical units responded with latencies only slightly longer than those obtained in the intact preparation. In the light of previous findings these electrophysio‐logical data suggest that, unlike carnivora, primates may possess the ventral spinal somatosensory pathway traditionally postulated on the basis of neurological material.
Acid‐Base Changes and Excitation‐Contraction Coupling in Rabbit Myocardium. II. Effects on Resting Membrane Potential, Action Potential Characteristics and Propagation Velocity
Authors: Jóhannsson M. , Nilsson E. 
Published: December 2008

AbstractThe effects of changes in acid‐base parameters on the resting membrane potential, action potential characteristics and propagation velocity were studied in isolated rabbit papillary muscles. Lowering extracellular pH from 7.4 to 6.7 in a bathing solution buffered with 10 mM histidine did not alter the resting membrane potential or action potential characteristics but caused a slight reduction in propagation velocity. A parallel increase in HCO3 concentration (up to 47 mM) and Pco2 at a constant extracellular pH of 7.4 caused a substantial decrease in action potential duration but did not alter the resting membrane potential or propagation velocity. The decrease in action potential duration was caused by the increase in HCO3 concentration. Propionate (47 mM) caused a shortening of the action potential which was of the same magnitude as for HCO3 but methylsulfate (47 mM) did not have this effect. The possible influence of these changes on the inotropic state of the myocardium and the cellular mechanisms involved are discussed.
Effects of Myocardial Infarction on Adrenergic Nerves of the Rat Heart Muscle, a Histochemical Study
Authors: Ahonen A. , Härkönen M. , Juntunen J. , Kormano M. , Penttilä A. 
Published: December 2008

AbstractThe anterior branch of the left coronary artery of the rat heart was ligated and the effects of anoxia on adrenergic nerves were studied histochemically using formaldehyde‐induced fluorescence for localization of norepinephrine. Greenish catecholamine fluorescence was associated in the normal or infarcted myocardium only with adrenergic nerves. Constant but not prominent changes were seen in adrenergic nerve fibers 2 or 4 h after ligation of the coronary artery; the number of delicate adrenergic fibers was reduced and some diffusion of the histochemical reaction was seen in small areas of the infarcted myocardium. Strong effects of anoxia were seen 8 h or more after ligation of the coronary artery. These were characterized by a prominent diffusion of the histochemical reaction and gradual disappearance of adrenergic structures in 2 to 4 days of anoxia. During the healing phase the appearance of numerous adrenergic nerve fibers was closely connected with the ingrowth of a new vascular bed into the infarction area. The observations indicate that adrenergic nervous structures of the myocardium resist the effects of anoxia, which may indicate the viability of sympathetic nerves in the infarcted area during long periods of anoxia.
Control of the Neurotoxicity of 6‐Hydroxydopamine by Intraneuronal Noradrenaline in Rat Iris
Authors: Sachs Charlotte , Jonsson Gösta , Heikkila Richard , Cohen Gerald 
Published: December 2008

AbstractIn vitrostudies with the neurotoxic compounds 6‐hydroxydopamine (6‐OH‐DA) and 6‐aminodopamine (6‐A‐DA) showed that noradrenaline (NA) markedly inhibited the autooxidation of 6‐OH‐DA, but not of 6‐A‐DA.In vivostudies of the adrenergic nerves in rat iris showed that the neurotoxic potency of 6‐OH‐DA, but not 6‐A‐DA, was increased after NA depletion by α‐methyl‐p‐tyrosine methylester(H44/68). Neurotoxicity was evaluated by measuring the associated decrease in3H‐NA uptake. lntraocular injection of NA counteracted the degenerative action of 6‐OH‐DA in both untreated and H44168 pretreated rats. Intraocular NA did not interfere with the neurotoxicity of 6‐A‐DA. Additionally, octopamine did not affect the rate of autooxidation nor the neurotoxic potency of 6‐OH‐DA or 6‐A‐DA. Control experiments with3H‐6‐OH‐DA showed that the intraneuronal NA levels did not significantly affect the intraneuronal accumulation of 6‐OH‐DA. The parallelism between thein vitroresults on autooxidation andin vivodata on neurotoxicity makes it appear that the neurotoxic potency of 6‐OH‐DA and 6‐A‐DA is closely associated with their rates of autooxidation. The control of the degenerative action of 6‐OH‐DA by intraneuronal NA may be mediated via reaction of NA with radicals formed from oxygen during autooxidation of 6‐OH‐DA.
The Action of Dibutyryl Adenosine‐3‘:5’‐Cyclic Monophosphoric Acid and Theophylline on the Isolated Cat Parotid Gland
Authors: Fritz M. E. , Grampp W. 
Published: December 2008

AbstractIn the isolated cat parotid gland intraarterially applied dibutyryl cyclic AMP (db‐CAMP) (1.0 mM) produced a slow, but often maintained salivary flow. db‐CAMP was also able to potentiate secretion evoked by supramaximal doses of intraarterially applied acetylcholine. Similar secretory effects were obtained also after intraarterial application of theophylline (1.0 mM). The secretory responses due to db‐CAMP or theophylline were unaccompanied by measurable acinar membrane potential changes and stayed unchanged after cutting the parasympathetic innervation of the gland and after blocking both cholinergic and β‐adrenergic receptors with atropine (10‐‐7M), and with D‐(‐)‐N‐isopropyl‐p‐nitrophenol‐ethanol‐amine (INPEA) (10‐‐5M), respectively. The possibility of the existence of an acinar adenylate cyclase system functionally linked to the β‐adrenergic membrane receptor is discussed.
Adenosine Triphosphate Dependent Calcium Uptake by Subcellular Fractions from Bovine Neurohypophyses
Authors: Russell J. T. , Thorn N. A. 
Published: December 2008

AbstractBovine neurohypophyses were fractionated by differential and density gradient ultracentrifugation and the Ca2+uptake and ATPase activities in the microsomal, mitochondrial and secretory granule fractions were studied. The microsomal and mitochondrial fractions accumulated Ca2+in the presence of ATP. The accumulation by the latter per mg protein was at least twice as large as by the former. This Ca2+accumulation was accompanied by liberation of inorganic phosphate (Pi). In the presence of sodium azide (2 mM) Ca2+uptake and Piliberation were inhibited in the mitochondrial, but not in the microsomal fraction. Further studies of the microsomal fraction revealed that the ATP‐dependent Ca2+uptake and Piliberation activities were temperature and pH‐dependent and required Mg2+. Both activities were stimulated by very low concentrations of Ca2+(1–10 μM) and were inhibited by EGTA (2 mM). N‐ethyl‐maleimide (2 mM) inhibited both the Ca2+uptake and ATPase activities of the microsomal fraction. These results suggest the presence of a membrane ATPase that is stimulated by both Ca2+and Mg2+. It is suggested that the observed Ca2+uptake activities are involved in maintaining a low axoplasmic free Ca2+concentration, thus playing an important role in the release mechanism of vasopressin by the neuro‐secretory terminals.
No Role for Zinc in the Storage of Histamine in Rat Peritoneal Mast Cells
Authors: Uvnäs Börje , ÅBorg Carl‐Hugo , Bergqvist Ulla 
Published: December 2008

AbstractThe histamine in the granules of mast cells has been proposed to be stored as a heparin‐zinc‐histamine complex. Due to its chelating action zinc should increase (double) the histamine binding capacity of heparin. We have determined the zinc content of isolated rat peritoneal mast cells to 2.4–4.1 nmol/106cells and of their granules to 13.0–21.4 nmol/mg dry weight. The corresponding amounts of histamine were 150 and 680 nmol respectively. The zinc content found is far (20 times) too low to allow for an adequate binding of histamine in a heparin‐zinc‐histamine complex.In vitrothe granules take up zinc in the same manner as they take up other cations and zinc competes with histamine for granule storage sites. Consequently, Hi‐uptake is reduced and not enhanced in the presence of zinc in the suspension medium.In summaryno evidence was found for a storage function of zinc in a heparin‐zinc‐histamine complex.
Distribution of an Adenohypophysial Constituent in the Body I. Whole‐body Autoradiographical Studies in the Mouse
Authors: Kihlström Jan Erik , Hall Håkan , Lakomaa Eeva 
Published: December 2008

AbstractA peptide with a molecular weight of about 5 000 has previously been shown to affect the output of semen in frogs and probably also in mammals. This sperm‐releasing substance is not part of any known gonadotropic hormone. The distribution of this substance has been investigated using whole‐body auto‐radiography. Radioactive material is incorporated into the epididymis, the adenohypophysis and probably also into the ovary.
The Diffusion Permeability to Water of the Rat Blood‐Brain Barrier
Authors: Bolwig Tom G. , Lassen Niels A. 
Published: December 2008

AbstractThe diffusion permeability to water of the rat blood‐brain‐barrier (BBB) was studied. Preliminary data obtained with the Oldendorf tissue uptake method (Oldendorf 1970) in seizure experiments suggested that the transfer from blood to brain of labelled water is diffusion‐limited. More definite evidence of such a limitation was obtained using the single injection technique of Crone (1963). 14C‐labelled sucrose was used as intravascular reference substance and tritium‐labelled water as test substance. The non‐exchanging (transmitted) fraction, I‐E = T, of labelled water during a single passage increased from 0.26 to 0.67 when the arterial carbon dioxide tension was changed from 15 to 85 mm Hg, a change increasing the cerebral blood flow about sixfold. This finding suggests that water does not pass the blood‐brain barrier as freely as lipophilic gases.
The Relationship between Arterial PO2 and Cerebral Blood Flow in Hypoxic Hypoxia
Authors: Borgström Lars , Jóhannsson Halldor , Siesjö Bo K. 
Published: December 2008

AbstractThe relationship between arterial oxygen tension (PaO2) and cerebral blood flow (CBF) in hypoxic hypoxia was studied in artificially ventilated and normocapnic rats. Changes in CBF were evaluated from arterio‐venous differences in oxygen content after 2, 5, 15 and 30 min exposure to PaO2 85, 75, 55, 45, 35 and 25 mm Hg. In separate experiments the PaO2 was decreased to 25 mm Hg for 1, 2, 5, 15 and 30 min in animals in which PaCO2 was allowed to fall by 5–10 mm Hg. There was a small, gradual increase in CBF when Pao, was lowered in steps from 130 to 55 mm Hg, and a more pronounced increase at PO2 values below 50 mm Hg. At PaO2 25 mm Hg CBF increased to values of 500% of normal. Significant increases in CBF were recorded at PaO2 values of 85 and 75 mm Hg in spite of the fact that previous studies have failed to record an elevatad tissue lactate content at these PO2 levels, and in spite of an unchanged cerebral venous PO2. When the PaO2 was reduced to 25 mm Hg CBF increased markedly already at 1 and 2 min, and this increase in CBF occurred even if PaCO2 was allowed to fall by 5–10 mm Hg. Previous results have shown that in such short periods enough lactic acid is not formed to induce a net tissue acidosis. The results thus give no support to the hypothesis that cerebral hyperemia in hypoxia is coupled to accumulation of lactic acid in the tissue.
Duration of Central Action of Angiotensin II Estimated by its Interaction with CSF Na+
Authors: Anderson B. , Leksell L. G. , Rundgren M. 
Published: December 2008

AbstractIn pre‐hydrated goats, an urge to drink persisted for approximately half an hour after combined infusions of angiotensin II and hypertonic (0.5 M) NaCl into the lateral or third cerebral ventricle. The intraventricular infusion of angiotensin/glucose solution, having no dipsogenic action of its own, markedly accentuated the dipsogenic and antidiuretic effects of the subsequent intraventricular infusion of hypertonic NaCl. The possibility is discussed that angiotensin may be bound at periventricular receptor sites where it continues to interact with Na+in eliciting thirst and ADH release for about half an hour.
Influence of Autonomic Nerves and Drugs on Myoepithelial Cells in Parotid Glands of Cat
Authors: Thulin Anders 
Published: December 2008

AbstractWhen a single electrical shock is applied to either the parasympathetic or to the sympathetic nerves a pressure rise is seen in the parotid duct of the cat, probably due to myoepithelial cell activation. No secretion occurred on single impulse stimulation. When repetitive stimulation was used both divisions of the autonomic nervous system could evoke secretion. The motor response to sympathetic stimulation was mediated via a‐receptors while secretion mainly was mediated via β‐receptors.
The Effect of Stimulation of the Cervical Sympathetic Chain on Regional Cerebral Blood Flow in Monkeys: A Study with Radioactively Labelled Microspheres
Authors: Alm Albert 
Published: December 2008

Abstract15 μm labelled microspheres were used to determine the effect of stimulation of the cervical sympathetic chain on blood flow through different parts of the brain and through some extracerebral tissues of the head in monkeys. Unilateral stimulation at 10 Hz for one min caused mean reductions in blood flow through the masseter muscle, the parotid gland, and the tongue of 76–94 percent in 9 monkeys, while in the same animals there were no convincing effects on regional cerebral blood flow.
Blood‐Brain Transfer of D‐Glucose, L‐Leucine, and L‐Tryptophan in the Rat
Authors: Brender Jytte , Andersen P. E. , Rafaelsen O. J. 
Published: December 2008

AbstractRecently Oldendorf developed a method for measurement of the early uptake of substances from the capillary bed into brain tissue after a single capillary passage of a bolus injected rapidly into the common carotid artery of the rat. The uptake of a test substance is expressed relative to the uptake of a highly diffusible reference substance, tritiated water. In this study experimental data are presented allowing to correct the uptake values for the unknown loss of tritiated water, so that the fractional unidirectional uptake (Extraction, E) can be calculated. This method is used to investigate the uptake kinetics for D‐glucose, L‐leucine, and L‐tryptophan. For the three substances investigated the uptake kinetics involved both saturation and linear kinetics. Km values of 11 mM for D‐glucose, 0.16 mM for L‐leucine, and 0.19 mM for L‐tryptophan were found. The uptake capacity, Vm, was calculated using a blood flow value of 0.85 ml/(g × min); Vm was for D‐glucose 1.6, for L‐leucine 0.027. and for L‐tryptophan 0.024 μmol/(g × min). The D‐glucose Vm in the present study is comparable with Vm values in the literature, and indicates that the method may be employed for quantitative analyses of the blood‐brain transfer of solutes.
Brain Energy Metabolism in Anesthetized Rats in Acute Anemia
Authors: Jóhannsson Halldór , Siesjö Bo. K. 
Published: December 2008

AbstractIn order to evaluate if pronounced anemic hypoxia gives rise to signs of cerebral oxygen lack the blood hemoglobin content was reduced to 6 and 3 g.(100 ml)‐1. Cerebral blood flow increased in spite of the fact that there was a moderate reduction in blood pressure, and in mean tissue CO2 tension, and in the absence of signs of an increased glycolytic rate in the tissue. With a reduction in a hemglobin content to 3 g.(100 ml)‐1 there was a moderate increase in tissue lactate content and associated changes in other carbohydrate metabolites and in amino acids of the type seen in hypoxic hypoxia, suggesting that tissue hypoxia was present. However, since the concentrations of phosphocreatine and adenine nucleotides remained constant this hypoxia must have been slight. It is concluded that there is cerebral vasodilation in the brain in pronounced anemic hypoxia, and that this vasodilatation, in combination with the reduced viscosity, creates favourable conditions for cerebral oxygenation.
Compensatory Increase in Choline Acetyltransferase Activity in Salivary Glands and Diaphragm Muscle of the Rat
Authors: EKSTRÖM JORGEN 
Published: December 2008

AbstractWhen the function of salivary glands was abolished by applying ligatures to their ducts and the function of one half of the diaphragm muscle was abolished by sectioning of its phrenic nerve, the choline acetyltransferase activity was found to be increased in not duct‐ligated glands and in the intact hemidiaphragm 4 weeks later. The increase was not seen within the first week. The increase in activity appears to be particularly manifested in the nerve endings, since it was seen in the hemidiaphragm but not in the phrenic nerve. Increased stream of impulses in the efferent nerves is thought to be the cause of this increase in choline acetyltransferase activity.
Effects of Drugs and Nerve Stimulation on the Spleen and Arteries of Two Species of Dogfish, Scyliorhinus canicula and Squalus acanthias
Authors: Nilsson Stefan , Holmgren Susanne , Grove David J. 
Published: December 2008

AbstractThe effects of drugs and nerve stimulation on the spleen of 2 species of dogfish have been examined by experiments with perfused spleens and isolated spleen and artery strips. Adrenaline, noradrenaline and phenylephrine, acting via alpha adrenoceptors, constrict the perfused spleen of both species, thereby releasing erythrocytes, and contract the isolated spleen and artery strips. Phentolamine competitively antagonizes the excitatory effects of adrenergic agonists. The responses of the spleen to acetylcholine are very irregular, and a rapid desensitization makes evaluation of the mode of action of this drug difficult. In the artery strips acetylcholine produces a dose‐dependent contraction. Fluorescent histochemistry reveals well developed adrenergic innervation of the arteries, and a few adrenergic terminals in the spleen. Stimulation of splenic nerves produces normally splenoconstriction in Squalus, which can be blocked by phentolamine but not by atropine. The nervous control of the Scyliorhinus spleen seems to be poor or lacking. It is concluded that the dogfish spleen, and maybe also the arteries, are to a large extent controlled by circulating catecholamines and (in Squalus) also by sympathetic adrenergic fibres.
The Postnatal Development of Some Twitch and Fatigue Properties of Single Motor Units in the Ankle Muscles of the Kitten
Authors: Hammarberg C. , Kellerth J‐O. 
Published: December 2008

AbstractContractions of single motor units in the gastrocnemius, soleus and pretibial flexor muscles were elicited by intracellular stimulation of the innervating motoneurones. Kittens being 1, 2, 6 and 10 weeks of age were used. The aim was to establish the pattern of postnatal differentiation of the adult motor unit types (Burke et al. 1973, 1974, Hammarberg and Kellerth 1975 b). In the developing type S units of the soleus muscle the mean value for contraction time showed a transient decrease during the early postnatal period, but the twitch half‐relaxation time (HRT), the duration of motoneurone post‐spike afterhyperpolarization (AHP) and the susceptibility to fatigue remained virtually unchanged during the age period studied. In the units of the developing fast twitch muscles the contraction time, HRT and susceptibility to fatigue were significantly different from those of the soleus units already at 1 week of age. At 6–10 weeks of age the contractile characteristics typical of the adult type FF and FR units were attained. The AHP duration gradually decreased up to 10 weeks of age, and it was then considerably shorter than both at 1 week of age and in the adult stage.
Relative Contribution of Superficially Bound and Extracellular Calcium to Activation of Contraction in Isolated Rat Portal Vein
Authors: Sigurdsson Stefan B. , Uvelius Bengt , Johansson Börje 
Published: December 2008

AbstractThe spontaneous electrical and mechanical activity of the isolated rat portal vein is abolished after only 2–3 min in nominally Ca‐free medium, and after 5–6 min there is no contractile response to depolarizing (122 mM K+), Ca‐free solution. In the present study we have examined the electrical and mechanical responses of the portal vein to depolarization with simultaneous readministration of Ca2+ (2.5 mM) after periods of variable length in Ca‐free standard solution. After 30 to 60 min of Ca depletion a slow contracture occurred in response to the high‐K+ solution with 2.5 mM Ca2+. When the period in Ca‐free medium was reduced below 30 min an early, faster phase appeared in the contracture response, and this phase was more rapid the shorter the time of Ca depletion. It is suggested that the slow contracture obtained after 30 min or more uses mainly extracellular Ca for activation and that the faster phase seen after shorter periods of Ca depletion is due to release of superficially bound Ca. This latter pool of tissue bound Ca does not alone produce contraction in response to depolarization, suggesting that extracellular Ca is required to trigger the release perhaps through a regenerative process.
Inhibition of Induced Pinocytosis in Amoeba proteus by Membrane Stabilizing Drugs
Authors: Josefsson J.‐O. , Johansson G. , Hansson S. Elisabeth 
Published: December 2008

AbstractThe effect of membrane stabilizing drugs on cation induced pinocytosis was studied inAmoeba proteus.Initially the presence of local anesthetic drugs during a pinocytosis cycle had a stimulating effect on channel formation, however, the capacity to develop pinocytotic channels was reversibly inhibited after a period of treatment with these drugs. Imipramine, vinblastine and the phenothiazines had effects similar to local anaesthetics. The local anesthetics inhibited pinocytosis in the following order: dibucaine>tetracaine> bupivacaine >lidocaine>procaine, and the phenothiazines: thioridazine>prochlorperazine>chlorpromazine > prometazine. Pinocytosis, when induced by Na+or tris, was more affected by the drugs and by calcium binding agents than pinocytosis induced by K+. After pretreatment with inhibitory concentration of dibucaine (3 × 10‐4M) the depolarization of the membrane and the conductance increase during pinocytosis were normal, while the increase of oxygen uptake during the pincoytosis cycle was abolished. Addition of Ca++before, during or after dibucaine treatment decreased the effect of the drug. Conversely, in dibucaine‐treated cells, cation induced pinocytosis was less inhibited by Ca++than pinocytosis in normal cells. Addition of EGTA to the inducing solutions potentiated the inhibitory effect of the drug. It is suggested that these drugs release Ca++from the cell surface and at higher concentration or after prolonged incubation time interfere with a Ca++mechanism which couples the membrane and contractile systems in the cytoplasm.