bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transport and Oxidation of Amino Acids and Glucose in the Isolated Exocrine Mouse Pancreas: Effects of Insulin and Pancreozymin
Authors: Danielsson Ake , Sehlin Janove 
Published: December 2008

AbstractThe uptake and oxidation of L‐alanine and L‐leucine as well as the oxidation of D‐glucose were studied in pieces of microdissected exocrine mouse pancreas. The main observations and conclusions were as follows. The rate of oxidation of D‐glucose was low and was only slightly enhanced by increasing its concentration in the medium from 3 to 20 mM. Even at a concentration as low as 0.1 mM, both amino acids were oxidized at a higher rate than D‐glucose. Thus, mouse exocrine pancreas seems to prefer amino acids to D‐glucose as substrate for its energy metabolism. The uptake of L‐alanine and L‐leucine in the exocrine cells was studied with a double‐label technique using 14C‐L‐glucose as an extracellular marker. Both amino acids were rapidly taken up and accumulated in the exocrine cells. D‐glucose inhibited both the uptake and oxidation of L‐alanine. The decreased rate of oxidation of this amino acid might have been due to the reduction in uptake. Stimulation of secretion by cholecystokinin‐pancreozymin increased the oxidation of D‐glucose, L‐alanine and L‐leucine. However, no effect on the transport of the amino acids into the exocrine cells was observed. Therefore the effect of CCK‐PZ on oxidation seems not to depend on an increased uptake of the amino acids. The presence of insulin (100 /<g/ml) stimulated the oxidation of D‐glucose, but not that of the amino acids. Insulin had no effect on the transport of the amino acids into the exocrine cells.
Comparison of the Lipolytic Activity of Circulating and Locally Released Noradrenaline during Acidosis
Authors: PaulHjemdahl  , Fredholm BertilB. 
Published: December 2008

AbstractThe influence of hypercapnic acidosis on the effects of i.v. noradrenaline (NA) infusions and of sympathetic nervous stimulation were studied in the isolated autoperfused subcutaneous adipose tissue of the dog. Acidosis increased resting vascular resistance in the adipose tissue. Infusion of NA (0.35‐0.69, μg/kg/min for 30 min) increased adipose tissue blood flow at both pH 7.4 and 7.0. Arterial increases in glycerol and FFA due to NA infusions were inhibited by 60–70 % during acidosis. Mobilization of these lipolytic products from the adipose tissue was impaired to the same degree. Sympathetic nervous stimulation (4 Hz for 5 min) lead to the same increase in vascular resistance at normal and acid pH. The lipolytic response,i.e.glycerol release, to nerve stimulation was unaffected by acidosis. FFA release was, however, reduced by about 40%.Release of3H‐NA by nerve stimulation from previously labelled adipose tissue was not significantly increased during acidosis. We conclude that inhibition of NA induced increases in arterial glycerol and FFA concentrations by acidosis can be explained by impaired mobilization from the adipose tissue. Furthermore, the lipolytic effect of locally released NA is not inhibited by acidosis, in contrast to the findings with circulating NA. This difference cannot to any major extent be explained by increased transmittor release during acidosis.
Change in Active State during the Staircase Phenomenon of Human Muscle
Authors: Rosenfalck Poul 
Published: December 2008

AbstractThe aim of this study was to determine the active state curve of normal and potentiated isometric twitch contractions of human muscle. Using Hill's (1949) two‐component model of muscle the active state curve was calculated from the course of isometric tension development. It was assumed that the force‐extension diagram of the series elasticity was exponential. Hill's characteristic relation between force and shortening velocity was modified to include the rise and decline in active state. Data from 4 m. adductor pollicis and 3 platysmas were analysed. In normal twitches active state had a maximum of about 0.5 Po occurring at one fifth to one third of the time to peak force, P0 denoting the isometric tetanic force. In potentiated twitches maximum intensities of 0.70‐0.85 P0 and of 0.8‐1.0 P0 were obtained in m. adductor pollicis and platysma respectively. In m. adductor pollicis the intensification of activation was most pronounced around the maximum of the curve.
Substrate Activation and Product Inhibition of LDH Activity in Human Skeletal Muscle
Authors: Karlsson Jan , Hulten Bodil , Sjodin Bertil 
Published: December 2008

AbstractSubstrate activation and product inhibition have been studied on LDH activity in both directions in human skeletal muscle. Km for the forward and backward reactions for pyruvate and lactate were found to be 0.8 × 10‐4 and 0.9 times 10‐2 M, respectively. For increases in concentrations of NAD and NADH the LDH activity was found to increase curvilinearly and no Km value could be obtained. Inhibition of the LDH activity corresponding to 50 % of Vmax was obtained for the forward reaction with a lactate concentration equal to 0.3 × 10‐2 M and for the backward reaction (pyruvate) the corresponding value was 1.0 X10‐4 M. With concentrations of lactate and pyruvate approximately corresponding to maximal values observed in skeletal muscle with exercise, the inhibition of LDH activity in both directions was equal to or more than 70 % of Vmax. It is concluded that in an in vitro system concentrations of lactate and pyruvate similar to what are observed under physiological conditions in human skeletal muscles will induce a significant product inhibition on LDH activity obtained from human skeletal muscles in both reaction directions. It seems reasonable to assume that the present in vitro findings might reflect functions operating in an in situ system. Thus it is possible that the products of the LDH catalysed reactions (lactate or pyruvate) might have a regulatory effect on the anaerobic glycolysis as well as the oxidation of lactate in human skeletal muscle.
Firing Behaviour of a Neurone Model Based on the Afterhyperpolarization Conductance Time Course and Algebraical Summation. Adaptation and Steady State Firing
Authors: Baldissera F. , Gustafsson B. 
Published: December 2008

AbstractF. Baldissera and B. Gustafsson. Firing behaviour of a neurone model based on the afterhyperpolarization conductance time course and algebraical summation. Adaptation and steady state firing. Acta physiol. scand. 1974. 92. 27–47.A preceding paper described the firing behaviour of a neurone model, in which the refractoriness was solely governed by a K conductance process similar to that underlying the afterhyperpolarization in the cat's a‐motoneurones (Baldissera and Gustafsson 1974 b). The present paper describes the firing behaviour of the same model implemented with algebraical summation of the consecutive AHP conductance. For the initial intervals after the onset of constant current the model is well simulating the successive changes in the frequency‐current (f/i) relations and the interspike voltage trajectories found in real motoneurones. The steady state f/i relation of the model can also display an upward deviation from linearity at higher current intensities, i.e. a ‘primary’ and a ‘secondary’ range of firing as described for real motoneurones (Kernell 1965 c). The results are discussed in relation to the terminology describing firing behaviour in motoneurones and to various hypotheses on firing control. It is concluded that the AHP conductance is the decisive factor for determining the f/i relations as well as the interspike voltage trajectories in motoneurones.
Excitation of Intradental Sensory Units by Pharmacological Agents
Authors: Oloart Leif 
Published: December 2008

AbstractRecordings were made from intradental sensory nerves in the tooth of the cat. Local application of bradykinin and histamine failed to induce impulse activity, even when applied to the exposed pulp, whereas 5‐hydroxytryptamine produced bursts of impulses with short latency, lasting a few seconds. Application of compound 48/80 induced an increase in impulse activity after a delay of some minutes and this activity persisted for about 2 h irrespective of whether the agent was removed or not. The impulse frequency decreased promptly when the temperature was raised and recovered when the temperature was lowered again. Pre‐treatment with polyphloretin phosphate (PPP) inhibited the excitatory action of compound 48/80. The threshold of excitation to cold stimulation was lowered after introduction of compound 48/80. Since the principal action of compound 48/80 is to release endogenous substances from mast cells the present findings may indicate that the increase in impulse activity is secondary to a release of biogenic substances. However, at present a direct action of compound 48/80 can not be excluded.
Incorporation of Imipramine into Isolated Rat Peritoneal Mast Cells in Vitro
Authors: Gripenberg J. 
Published: December 2008

AbstractThe incorporation of imipramine into isolated rat peritoneal mast cells was fluorometrically studiedin vitro.The binding of imipramine was characterized by the following features: 1. it took place in two phases, the first of which was very rapid, 2. it increased with increasing exogenous concentration in a sigmoidal fashion, 3. it increased with increasing exogenous pH, 4. it was dependent on neither temperature nor calcium ions in the medium nor did the binding occur specifically to mast cells but also to leucocytes, 5. it was reduced by several imipramine derivatives, tricyclic antidepressants and 5‐hydroxytryptamine at high concentrations, 6. about 40 % of the cell‐bound drug was easily washed out; the remaining 60 % represented a level approached after prolonged washing and seemed to be fairly tightly bound, 7. the subcellular location of imipramine in mast cells was different from that of 5‐hydroxytryptamine, indicating a nongranular binding of the drug. It is concluded that imipramine binds to mast cells in a passive manner and is associated with the cell membrane where it seems to be bound to at least 2 different sites. At low concentrations imipramine is probably bound to sites specifically influencing the operativeness of the amine carrier. Higher concentrations of imipramine results in binding to nonspecific sites resulting in impairment of the structure and function of the cell membrane.
Parallel Activation of Dynamic Fusimotor Neurones and a Climbing Fibre System from the Cat Brain Stem. II. Effects from the Inferior Olivary Region
Authors: Jeneskog Torgny 
Published: December 2008

AbstractClimbing fibre activity in the cerebellar paramedian lobule and hind limb dynamic fusimotor activation, caused by electrical stimulation in the medial parts of the medulla, were studied in halothane anesthetized cats. Three regions influencing dynamic fusimotor neurones were found. From one of these, corresponding to the nucleus reticularis gigantocellularis, descending activity proceeded in the contralateral ventrolateral funiculus. From the other two, corresponding to parts of the inferior olive and the pyramid respectively, the spinal pathways were located in the contralateral dorsolateral funiculus. The pathway from the olivary region seemed to be identical to a previously described dynamic facilitatory pathway activated in the rubral region. Climbing fibre activity in a hind limb zone of the paramedian lobule was evoked with short latency from caudal parts of the principal olive, but, probably transsynaptically, also from wider areas within the inferior olive. On stimulation in the red nucleus orthodromic responses were found in one region overlapping the nucleus reticularis gigantocellularis, and in another one, situated in the caudal parts of the principal olive. In this latter region, postsynaptic activity was recorded also from the DLF‐SOCP. Evidence for a convergence between this pathway and the one from the rubral region was obtained.
Release of Kallikrein from Isolated Cellular Organelles of the Rat Submandibular Salivary Gland
Authors: Gautvik K. M. , Kriz M. 
Published: December 2008

AbstractSubcellular organelles which contained kallikrein were isolated from homogenates of rat submandibular salivary glands by sucrose density gradient centrifugation. Kallikrein activity and BAEE‐esterase activity were localized to the same subcellular fractions. The BAEE‐esterase containing organelles lysed easily in normoosmolar buffer solutions and liberated soluble enzyme. The spontaneous lysis of these organelles was reduced in hyperosmolar solutions. The presence of calcium (2.6–27 mM) stabilized the enzyme containing organelles, but magnesium (25 mM) and potassium (60 mM) had no such effect. Replacement of sodium with sucrose and removal of calcium, magnesium or potassium had also no effect on enzyme release.
Tactile Placing Reactions in Chronic Spinal Kittens
Authors: Forssberg H. , Grillner S. , Sjöström A. 
Published: December 2008

AbstractTransection of the spinal cord at the level of Th 12 to L 1 was performed in 6–14 days old kittens. The kittens were kept for several months after the operation. During this period tactile stimuli applied to the dorsum of the hindpaw could evoke a flexion followed by an extension and a placing of the limb in a more rostral position. These reactions have been studied by recording the EMG activity and filming the movement. It is concluded that it must be regarded as tactile placing, which contrary to what has hitherto been assumed is not a reflex relayed in higher nervous structures, but rather a complex form of spinal reflex.
The Influence of Sympathetic Activity and Histamine on the Blood‐Tissue Exchange of Solutes in Canine Adipose Tissue
Authors: Linde By Birgitta , Chisolm Guy , Rosell Sune 
Published: December 2008

AbstractBy means of a single injection technique diffusion capacities for14C‐sucrose and3H‐polyethylene glycol (M.W. 800–1000) (PEG), expressed as the PS‐product of Renkin, were determined in dog subcutaneous adipose tissue.Under resting conditions PS for sucrose and PEG were approximately 2 and 1 ml × min‐1× 100 g‐1respectively. During maximal vasodilatation induced by prostaglanclin E2(PGE2) and papaverine the PS‐products were approximately doubled. The effects of sympathetic nerve stimulation (1–6 Hz) and histamine on the diffusion capacities were compared with controls at the same blood flow. During sympathetic nerve stimulation PS for sucrose increased 15 % in spite of a vasoconstriction. When superimposed on a maximal vasodilatation sympathetic nerve stimulation induced increases in PS for sucrose of approximately 40%and in PS for PEG of about 20 %. Histamine increased PS for sucrose 40%in a dosedependent fashion compared with a vasodilatation of the same magnitude induced by papaverine or PGE2. The results indicate that sympathetic nerve stimulation causes an increase in vascular permeability for solutes in canine subcutaneous adipose tissue. Histamine seems to have the same effect.
Choroid Plexus Uptake of Acetylcholine
Authors: Winbladh B. 
Published: December 2008

AbstractAcetylcholine (Ach) is accumulated by rabbit choroid plexa in vitro by active transport. The transport system seems to be identical to that for choline (Ch), and has a higher capacity: Calculated maximal speed varied between 10 and 60 mmol × min ‐1× kg‐1 wet weight. The choroid plexa contained a significant cholinesterase (ChE) activity which seemed to be localized intravascularly. ACh was not metabolized by the tissue i.e. intravascular concentrations of accumulated ACh were low. The cholinesterase inhibitor (ChEI) physostigmine inhibited ACh and Ch uptake, while the two ChEI:s soman and sarin stimulated the uptake of both ACh and Ch. The relative stimulation of the ACh uptake by soman increased with increasing ACh concentration in the incubation medium. The stimulation of ACh (10‐5 M) uptake was not significantly different at soman concentrations ranging from 10‐3 to 10 ‐6 M. Soman did not enhance the release of ACh from tissue preincubated at 10‐5 or 10‐3 M ACh for 15 min. The results are discussed in relation to ACh and Ch transport in brain slices. Further, possible localizations of the transport mechanism are briefly discussed.
Comparison between Effects of Cyclic AMP, Dibutyryl Cyclic AMP and Luteinizing Hormone on Ovarian Glycolysis
Authors: Herlitz By H. , Hamberger L. , Ahrén K. 
Published: December 2008

AbstractPrepubertal rat ovaries were incubated in medium containing 5.5 mM glucose and various concentrations of cyclic AMP (cAMP) and dibutyryl cyclic AMP (dbcAMP). Glucose uptake and lactic acid production were stimulated in presence of 5 mM cAMP. The effect was less pronounced with higher concentrations, and 25 mM cAMP inhibited ovarian glycolysis compared to control ovaries. A biphasic effect was also obtained with dbcAMP: a dose‐dependent increase with lower concentrations (0.1–5 mM) and smaller effects with higher concentrations. Luteinizing hormone (LH) stimulates ovarian glycolysis with a linear dose‐response relationship over an extremely wide range of concentrations (Hamberger and Ahren 1967). The stimulatory actions of dbcAMP and LH on ovarian glycolysis were augmented by low concentrations of aminophylline (0.5‐1 mM). No additive effects were seen when LH and dbcAMP were used together in maximal stimulatory concentrations. LH, cAMP and dbcAMP were also compared as to their lipolytic actions on the ovary. Lipolysis as judged by glycerol release was markedly enhanced by dbcAMP while the two other substances had only marginal effects. When bovine serum albumin (acceptor for fatty acids) was present in the medium, the dose‐response curve of the effect of dbcAMP on ovarian glycolysis was dramatically changed, indicating an interaction between the lipolytic and the glycolytic effects of this compound.
Effects of Gonadotrophins, Dibutyryl Cyclic AMP and Prostaglanclin E2 on Amino Acid Transport and Glycolysis in Isolated Rat Corpora Lutea
Authors: Herlitz By Hans 
Published: December 2008

AbstractCorpora lutea (CL) were isolated by free hand dissection from ovaries of 34–39 day‐old Sprague‐Dawley rats injected with 10 IU Pregnant Mare's Serum gonadotropin (PMSG) when 30 days old leacling to ovulation in the morning of day 33. Injection of luteinizing hormone (LH) to rats 2 h before removal of the ovaries stimulated the in vitro uptake of the non‐utilizable amino acids, a‐aminoisobutyric acid (AIB‐14C) and 1‐amino‐cyclopentane‐carboxylic acid (cycloleucine‐3H) by 3‐day‐old CL during a subsequent incubation in Krebs bicarbonate buffer. Prolactin and FSH were without effects. Addition of LH directly to the incubation medium did not stimulate amino acid uptake of the isolated CL, while addition of dibutyryl cyclic AMP (dbcAMP) enhanced this uptake. Glycolysis was estimated by determination of lactic acid accumulation in die incubation medium. When LH was injected to the animals 2 h before sacrifice, lactic acid production of 3‐day‐old CL was stimulated during a subsequent incubation period. Addition of LH in vitro caused a slight increase in the rate of glycolysis, and dbcAMP and prostaglanclin E2 (PGE2) also exhibited stimulatory effects on lactic acid production by the incubated CL. In a few experiments rats with 7‐day‐oId CL were given injections of LH. While amino acid uptake was not stimulated in these old CL, LH did enhance the rate of glycolysis in these CL.
Effects of Repetitive Stimulation on Membrane Potentials and Twitch in Human and Rat Intercostal Muscle Fibres
Authors: Hanson By Jerker 
Published: December 2008

AbstractMembrane potentials of human and rat external intercostal muscles have been studied in vitro at body temperature, and contraction curves at both body and room temperature. Histochemical staining of the entire preparation used in the experiment was performed. The resting membrane potential was on the average somewhat higher in human than in rat intercostal muscle fibres. The mean duration of the spike was 1.50 ms for the human fibres and 0.89 ms for the rat fibres. The mean contraction times were 79 and 11 ms, respectively. In the randomly taken human muscle fibre bundles the contraction times and the half‐relaxation times tended to be longer in preparations with many type I fibres (low ATPase activity) than in those with the same amount of type I and type II (high ATPase activity) fibres. Repetitive stimulation of human muscle fibres had very small effects. In rat muscles stimulation at 10 Hz for 30 s caused a marked increase in the twitch amplitude, an increase in the spike duration and in the amplitude of the early negative after‐potential. In both preparations the contraction speed was slower at room temperature than at body temperature. In rat intercostal muscles the twitch amplitude was higher at room temperature than at body temperature; in the human muscles it was the same. The twitch: tetanus ratio at body temperature was higher in human than in rat intercostal muscles.
Decremental Conduction, in Normal Human Nerves Subjected to Ischemia?
Authors: Nielsen By V. Kamp , Kardel T. 
Published: December 2008

AbstractThe effect of ischemia on the maximal orthodromic sensory and motor nerve conduction was studied in the digit 1‐elbow segment of the median nerve in 24 normal subjects. Action potentials were recorded at 2, 3 or 4 sites along the nerve. The latency of the potentials increased as a function of the duration of ischemia and of the distance from the point of stimulation. The earliest indication of an impaired nerve function was a decrease in the sensory action potential amplitude. During ischemia the length of the nerve segment, through which the potential was propagated, gradually became shortened. This was seen in sensory as well as in motor nerves. The sensory threshold to electrical stimuli (digit 3) had a two‐phasic course: During 15 min of ischemia it was almost stationary despite a severe reduction of the conduction velocity and of the potential amplitude. Then a rapid increase took place, coincicling with the extinction of the potential recorded at the elbow just below the occlucling cuff. The conduction parameters were normalized shortly after reestablishment of the circulation in the arm. The results indicate that action potentials become conducted with decrement during ischemia.
Choline Acetyltransferase Activity in Rat Salivary Glands Enlarged by Isoprenaline Treatment
Authors: EKSTRÖM JÖRGEN 
Published: December 2008

AbstractCertain procedures have earlier been found to cause the weight of the rat parotid gland to vary. After these procedures the choline acetyltransferase activity in the gland was also found to have changed in the same direction as the weight. This might suggest that variations in the gland mass in itself could influence the choline acetyltransferase activity. However, the present study shows that this does not seem to be the case, since a marked enlargement of the parotid gland, induced by isoprenaline treatment, can occur without being accompanied by any increase in the activity of this enzyme.
Effect of Atropine on Hypoglycemic Release of Gastrin in Man
Authors: Stadil F. , Malmstrøm J. , Rehfeld J. F. , Miyata M. 
Published: December 2008

AbstractHypoglycemic release of gastrin has been supposed solely to be due to vagal release. In this report the atropine resistance of the gastrin response to insulin was examined. 9 normal subjects were studied twice. 0.2 IU of insulin/kg i.v. was injected in each study, but in one atropine (30 μg/kg i.m.) was injected prior to insulin. Serum gastrin concentrations were measured by radioimmunoassay. Blood glucose concentrations did not differ in the two studies. Atropine almost abolished gastric output of acid. Gastrin concentrations rose after insulin and slightly more after atropinization. In four of the subjects a second late gastrin increase was observed after atropine. It is concluded that in man a major part of the hypoglycemic release of gastrin is independent on a cholinergic mechanism.