bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liver Hemodynamics and Liver Function in Cats during Graded Hypoxic Hypoxemia
Authors: Larsen Jens Anker , Krarup Niels , Munck Anders 
Published: December 2008

AbstractIn 15 cats, anesthetized with chloralose and curarized, liver hernodynamics and liver function were followed during graded hypoxic hypoxemia. Hepatic arterial and intrahepatic portal venous conductance were not influenced by hypoxia, whereas severe hypoxemia increased gastrointestinal conductance. Total liver blood flow remained constant and hypoxemia was compensated for by an increase in hepatic extraction of oxygen approaching 100% Only when the hepatic venous PO2 fell below 5–10 mmHg did hypoxemia decrease liver function. The results indicate that the sinusoidal perfusion is homogeneous.
Convergence on Interneurones Mediating the Reciprocal Ia Inhibition of Motoneurones I. Disynaptic Ia Inhibition of Ia Inhibitory Interneurones
Authors: Hultborn H. , Illert M. , Santini M. 
Published: December 2008

AbstractInterneurones identified as mediating the disynaptic reciprocal Ia inhibition of motoneurones (referred to as “Ia inhibitory interneurones”) were recorded in the lumbar spinal cord of the cat. It was revealed that the Ia inhibitory interneurones themselves receive disynaptic Ia inhibition. The muscles from which this inhibition is evoked are strictly antagonistic to those supplying their Ia excitation. Similar to the Ia inhibition in motoneurones the Ia inhibition in the Ia inhibitory interneurones is decreased when preceded by an antidromic stimulation of ventral roots. Furthermore, transmission of Ia inhibition to the Ia inhibitory interneurones is facilitated from ipsilateral and contralateral primary afferents as well as several supraspinal pathways analogous to earlier findings for the Ia inhibition of motoneurones. The pattern and control of the Ia inhibition of motoneurones and of Ia inhibitory interneurones display so striking similarities that it is suggested that identical interneurones are responsible. The conclusion thus emerges that “opposite” Ia inhibitory interneurones (i.e. interneurones monosynaptically connected to antagonistic muscles) are mutually inhibiting each other. The functional significance of this organization is discussed.
Towards a Valid Technique of Sampling Fish Muscle to Determine Redox Substrates
Authors: Börjeson Hans , Fellenius Erik 
Published: December 2008

AbstractThe redox substrates—lactate, malate, α‐glycerophosphate, dihydroxy acetonephosphate and pyruvate—have been determined in liver and muscle tissue from young salmon. The redox quotients have also been calculated. The freeze clamping technique was used and reliable samples of fish muscle for the determination of lactate were obtained with the aid of a pair of pliers with a gear mechanism. It was established that the lactate content in the body muscle is in close agreement with that in the blood from rested salmon parr. The concentrations of redox substrates are in good agreement with those found in mammalian tissue. The determination of the content of glycogen in fish muscle is discussed in the light of the results obtained in this study.
Effects from the Vestibulospinal Tract on Transmission from Primary Afferents to Ventral Spino‐cerebellar Tract Neurones
Authors: Baldissera F. , Roberts W. J. 
Published: December 2008

AbstractConvergence of vestibulospinal and segmental effects onto spinal interneurones which project to the ventral spino‐cerebellar tract (VSCT) neurones has been studied by intracellular recording in VSCT cells. The disynaptic Ia IPSPs evoked in a group of VSCT neurones from the quadriceps nerve are monosynaptically facilitated by the vestibulospinal tract while there was no facilitation of Ia IPSP evoked from a flexor nerve. These results support the view that Ia inhibition to VSCT cells and motoneurones is mediated by common interneurones. The disynaptic inhibition evoked in other VSCT cells from the vestibulospinal tract is facilitated by volleys in the contralateral flexor reflex afferents (FRA) or bilaterally from the FRA. It is postulated that these actions are mediated by collaterals of the interneurones responsible for the analogous effects in motoneurones. Findings are reported suggesting that the monosynaptic vestibulospinal EPSP in VSCT cells in most cases is collateral to the excitatory input to the last order interneurones of reflex pathways from the FRA to motoneurones and only exceptionally to the corresponding input to Ia inhibitory interneurones. In many VSCT cells the vestibulospinal tract evoked disynaptic EPSPs which are facilitated from the FRA; the functional significance of this actions is uncertain. The results are consistent with the hypothesis that VSCT neurones signal information on interneuronal transmission to motoneurones.
Modification of the Gastric Secretory Response to Sham Feeding by Acidification of the Antrum and the Duodenum in Dogs
Authors: Sjödin Lars 
Published: December 2008

AbstractThe effect of closure of a gastric cannula on the acid response to sham feeding was studied in Pavlov‐pouch dogs with intact antro‐duodenal regions as well as in antrectomized dogs with gastroduodenostomies. In the latter dogs, the sham feeding response was augmented by infusions of low doses of exogenous gastrin. The acid output after sham feeding in intact dogs was reduced on average by 59% by closure of the gastric cannula. In antrectomized dogs receiving a back‐ground stimulation with gastrin, the response to ham feeding was not inhibited by closure of the cannula. The results suggest that the observed hypersecretory response to sham feeding after diversion of gastric acid from antrum and duodenum is mainly due to inactivation of antral inhibitory mechanisms. The pepsin secretion following sham feeding was not consistently changed by closure of the gastric cannula.
Effects on Renal Water and Sodium Excretion of Infusions of either Iso‐Osmolar Saline or a Hypo‐Osmolar Solution of Non‐Electrolytes
Authors: Bie Peter 
Published: December 2008

AbstractThe effects of iso‐osmolar and hypo‐osmolar volume expansion on renal water and sodium excretion were studied in dogs during light chloralose anesthesia. Saline or a hypo‐osmolar solution of glucose and urea was given i.v. (20 ml/kg b.wt. in 60 min). From the start of this infusion the combined weight of the hydration infusate and the dog was maintained constant by a servo system, which controlled the rate of infusion of a hypo‐osmolar solution. Consequently the degree of hydration increased linearly during the infusion period after which it remained constant throughout the experiment. No increase in free water clearance was seen after iso‐osmolar volume expansion. The rate of excretion of sodium increased considerably. Hypo‐osmolar volume expansion provoked a water diuresis during which the rate of excretion of sodium fell to less than 0.1 μmol/kg b.wt. min. It is concluded that under the present circumstances infusion of iso‐osmolar saline is not associated with a decrease in the rate of secretion of vasopressin.
Effect of Strength Training on Enzyme Activities and Fibre Characteristics in Human Skeletal Muscle
Authors: Thorstensson Alf , Hultén Bodil , Döbeln Wilhelm von , Karlsson Jan 
Published: December 2008

AbstractProgressive strength training was performed 3 times a week for 8 weeks by 14 healthy male students (19–31 yrs). The training program consisted mainly of dynamic exercises for the leg extensors with maximal or close to maximal loads. The training caused significant improvements in dynamic and isometric strength. One repetition maximum in squats increased with 67%, Sargent jump with 22%, and maximal voluntary isometric contraction (MVC) with 13 %, respectively. Body weight and leg muscle circumferences remained unchanged after training, whereas total body potassium, lean body mass and calculated total muscle mass increased, suggesting a change in body composition with training. Muscle biopsies were obtained from vastus lateralis for fibre analyses and determination of enzyme activities. There were no changes in muscle fibre composition or fibre area with training. The activities of Mg2+ stimulated ATPase, creatine phosphokinase and phosphofructokinase remained unchanged, whereas myokinase activity was increased after training (from 1.41 to 1.52 moles × 10‐4× g‐1× min‐1, p > 0.05). After training significant correlations (p > 0.01) were demonstrated between Mg2+ stimulated ATPase activity and % fast twitch fibres (% FT) (r = 0.67), as well as between myokinase activity and % FT (r=0.86).
Mitochondrial Cytochrome Concentrations in Rat Heart and Liver as a Consequence of Different Hypoxic Periods
Authors: Kinnula Vuokko L. 
Published: December 2008

AbstractRat heart and liver cytochrome concentrations were determined after three hypoxic conditions (atmospheric pressure 50.5 kPa, 40.8 kPa and 38.0 kPa) lasting one week and two weeks. The heart showed clear hypertrophy which was 38% in most severe hypoxia (38 kPa, 2 weeks). A small decline in the liver weight to body weight ratio was observed, this decrease being 21% in the most severe case. During the hypoxic periods the mitochondrial cytochrome concentration decreased. This phenomenon was more obvious when the degree of hypoxia was increased and more pronounced after 2 weeks than one week. The heart and liver showed quite similar patterns in this respect. In most severe hypoxia the decreases in the liver were 29% for cytochrome aa3, 30% for cytochrome b, 20% for cytochrome c and 15% for cytochrome c1, with the concentrations expressed on mitochondrial protein basis. The corresponding values in the heart were 31%, 43%, 28% and 22%. It can be concluded that in mammals the mitochondrial cytochrome content probably varies according to the amount of oxygen available.
A Computer Program for an Open Two Compartment System Distinguishing Three Models
Authors: Cederblad G. , Floderus A. , Karlsson K. E. 
Published: December 2008

AbstractA digital computer program is described for the estimation of parameters in an open two compartment system distinguishing 3 models. The mathematical function to be fitted to a given set of experimental data is given initial estimates for the parameters of the function. The program uses an iterative procedure to adjust the parameters until the sum of squares of residuals has converged to a minimum. Assuming that a given substance is introduced into compartment 1, the function can be fitted to the set of experimental data of that compartment. A set of experimental data from compartment 2 can also be included in the minimizing function. Two optional weighting functions are presented. From the constants of the two‐exponential functions the physiological parameters of the three models are determined. Experimental observations of compartment 1 only allow for calculation of physiological parameters of two of the models.
Effects of Colchicine and Vinblastine on Axonal Transport of Choline Acetyltransferase in Rat Sciatic Nerve1
Authors: Dziegielewska K. M. , Saunders N. R. , Evans C. A. N. , Skacel P. O. , Häggendal C. J. , Heiwall P.‐O. , Dahlström A. B. 
Published: December 2008

AbstractThe effects of colchicine (0.5–10‐2 M) and vinblastine (10‐2‐10‐5 M) upon axonal transport of choline acetyltransferase (CAT) and on nerve impulse conduction have been investigated in the rat sciatic nerve. High concentrations of colchicine (0.5 M) and vinblastine (10‐2 M) blocked completely both axonal transport of CAT and impulse conduction. 10‐3 M vinblastine did not affect impulse conduction until 20–22 h after injection, but this concentration of vinblastine did block CAT transport; 5 × 10‐5 and 10‐4 M vinblastine blocked CAT transport but not impulse conduction. 10‐2 M and 10‐1 M colchicine were without effect on impulse conduction, but did produce substantial, although incomplete, block of CAT transport. The results are discussed in relation to the possible involvement of microtubules in transport of CAT.
Isometric and Isotonic Length‐Tension Relations and Variations in Cell Length in Longitudinal Smooth Muscle from Rabbit Urinary Bladder
Authors: Uvelius Bengt 
Published: December 2008

AbstractIsometric and isotonic length‐tension relations of longitudinal smooth muscle from rabbit urinary bladder were studied together with muscle cell length and tissue structure as revealed histologically. In vivo strip length at a bladder volume of 10 ml is referred to as L10. The smooth muscle was relaxed by Ca2+‐free solution and contracted by K+‐high solution with different Ca2+‐concentrations. Maximal active force, 12.5±0.4 N/cm2 (S.E., n ‐ 11), for whole strips was attained at a length of 206±4% (S.E., n 5) of L10. Passive tension at this length was about 15% of total tension. After correction for amount of connective tissue, maximal active tension of pure muscle bundles was 19 N/cm2. Up to about 165% of L10 isometric and isotonic length‐tension relations were identical; if the muscle was stretched beyond this, it failed to shorten isotonically to the same length as when contracting from a shorter starting length. This decreased shortening capacity was reversible if the muscle was shortened passively. The extent of shortening against zero load was dependent on degree of activation suggesting an internal resistance to shortening. A linear relationship was found between bladder radius and muscle cell length, indicating that no slippage occurs between the cells when the bladder is filled. Mean cell diameter in the nuclear region at L10 was 7.2±0.2 μm (S.D., n = 10). Mean maximal active tension per cell was calculated to be 2.3·10‐6 N and occurred at a cell length of 655 μm.
Cardiac Receptors in Ducks — A Link between Vasoconstriction and Bradycardia during Diving
Authors: Blix Arnoldus Schytte , Wennergren Göran , Folkow Björn 
Published: December 2008

AbstractIt has been demonstrated that cardiac receptors, most likely of the left ventricular type, are present also in the duck's heart. These receptors and their reflex responses (i.e. bradycardia and hypotension) could be blocked by intrapericardial administration of lidocaine. Initially, such receptor blockade did not affect efferent vagal control of heart rate, as revealed by undiminished bradycardia in response to a standardized vagal stimulation. After cardiac receptor blockade, however, the duck's normal bradycardia response to head immersion was greatly reduced. The cardiovascular response to submersion was now instead characterized by a marked rise in arterial pressure, with superimposed bouts of intensified bradycardia and pressure reduction, evidently induced reflexly from the arterial baroreceptors. Meanwhile, the bradycardia response to standardized efferent vagal stimulation was still the same as before intrapericardial lidocaine injection. These results suggest that the marked rise in cardiac filling pressure following the intense chemo‐receptor‐induced constriction of both resistance and capacitance vessels, activates ventricular stretch receptors signalling in vagal afferents. Apparently, the activation of these receptors contributes crucially to the bradycardia and reduction of cardiac output, which balance off the greatly increased peripheral resistance in the diving duck.
Blood Flow Changes in the Submaxillary Gland of the Rat on Parasympathetic and Sympathetic Nerve Stimulation
Authors: Thulin Anders 
Published: December 2008

AbstractBlood flow and secretion from the submaxillary gland of the rat was recorded. Stimulation of the chordalingual nerve evoked vasodilatation which was little, if at all, decreased after administration of atropine. The secretion evoked on parasympathetic nerve stimulation was greatly reduced but not totally abolished by parasympatholytic agents. Stimulation of the cervical sympathetic trunk evoked secretion, which was mediated both via α. and β‐adrenoceptors and vasoconstriction which was abolished by dihydroergotamine, and thus seemed to be mediated via α‐adrenergic receptors. After α‐adrenoceptor blockade vasodilatation was seen on sympathetic nerve stimulation. This was abolished by the β‐adrenoceptor blocking agent propranolol.
Excitability Changes of the Inspiratory ‘Off‐switch’ Mechanism Tested by Electrical Stimulation in Nucleus Parabrachialis in the Cat
Authors: Euler Curt von , Trippenbach Teresa 
Published: December 2008

AbstractThe time course of the excitability of the inspiratory ‘off‐switch’ mechanism with and without phasic vagal stretch receptor feedback has been studied in cats under light pentobarbitone anesthesia by electrical stimulation in the rostral pons using brief tetanic stimulation (300 Hz for 0.2 s). The threshold strength required just to elicit inspiratory ‘off‐switch’ was high early in inspiration and fell steeply with time. The threshold curves were steeper with than without phasic vagal feedback, and the difference reflects the phasic vagal contribution to the excitability of the inspiratory ‘off‐switch’ mechanism. In the absence of phasic vagal feedback the time course of this threshold curve usually corresponded closely to that of the ‘integrated’ phrenic activity at all PCO2 levels and body temperatures tested indicating that the ‘integrated’ phrenic activity can be used as an index of the centrally generated inspiratory activity. In response to a rise in PCO2 both the rate of change of the excitability of the inspiratory ‘off‐switch’ mechanism and its initial threshold level was increased. Changes in body temperature caused no change in the initial threshold but produced marked changes in the rate of rise of the ‘off‐switch’ excitability. Following an ‘augmented breath’ the inspiratory ‘off‐switch’ threshold was markedly reduced.
Active Transport of3H‐Bretylium in the Rat Vas Deferens in vitro
Authors: Ross Svante B. , Kelder Diana 
Published: December 2008

AbstractThe uptake and efflux of3H‐bretylium in slices of the rat vas deferens were examined. The uptake of bretylium was temperature, Na+and Cl‐dependent, sensitive to 6‐hydroxydopamine but insensitive to reserpine. The uptake was inhibited by desipramine, (+)‐amphetamine, imipramine methiodide and cocaine, whereas the local anaesthetics millicaine and lidocaine were poor inhibitors. The spontaneous efflux was very slow at 0°C and slow at 37°. Desipramine accelerated the efflux probably by inhibiting the re‐uptake of bretylium. (+)‐Amphetamine, low external Na+, high external K+and ouabain caused a pronounced increase in the efflux at 37°C but was almost without effect at 0°C. The efflux evoked by (+)‐amphetamine, low Na+and ouabain was inhibited by desipramine, imipramine methiodide and cocaine, whereas millicaine and lidocaine had very poor effects. The increase of bretylium efflux by hypertonic K+was only slightly inhibited by desipramine and partially antagonized by omission of Ca2+in the medium. The results obtained indicate that bretylium was taken up in noradrenergic neurones by the noradrenaline transport mechanism and that the efflux of bretylium produced by (+)‐amphetamine, low external Na+, low external Cl‐and by ouabain occurred by the same transport mechanism as the uptake but now working in the outward direction whereas the efflux induced by high K+seemed to occur mainly with another mechanism.
Potentiation of Anaphylactic Histamine Release from Isolated Rat Pleural Mast Cells by Rat Serum Phospholipids
Authors: Sydbom A. , Uvnäs B. 
Published: December 2008

AbstractIsolation of sensitized rat mast cells by density gradient centrifugation in Ficoll decreases the histamine release obtained when they are subsequently exposed to antigen. The histamine release from such isolated cells is potentiated by the addition of 2 % boiled rat serum. This potentiation is dose‐dependent and has a temperature optimum of about 25°C. The potentiating activity was localized to the serum phospholipid fraction. Of the pure phospholipids studied (LPC, PC, PE, PI, PS and SM) only phosphatidylserine and lysophosphatidylcholine were found to potentiate the histamine release. The mechanism behind this potentiation is discussed and it is suggested that the potentiation by phosphatidylserine and lysophosphatidylcholine is due to a requirement of these phospholipids for the ion exchange (Na+, K+and Ca++) or the adenylcyclase activity essential for the histamine release process.
Gustatory Effects of Miraculin, Monellin and Thaumatin in the Saguinus Midas Tamarin Monkey Studied with Electrophysiological and Behavioural Techniques
Authors: Hellekant G. , Glaser D. , Brouwer J. N. , Wel H. van der 
Published: December 2008

AbstractA comparative electrophysiological and behavioural study has been made in 17 closely related monkeys of the new world species, Saguinus midas tamarin. The electrical activity in the chorda tympani proper nerve of two of the monkeys was recorded during the application to the tongues of 0.02% monellin and thaumatin, 0.5 % miraculin and stimuli representing the four taste qualities. It was observed that monellin and thaumatin gave no or little response and that miraculin enhanced the response to the sour stimulus, but not that to any other taste quality. Behavioural studies were then made with a two‐bottle preference test in 15 monkeys. It was found that the animals did not discriminate or discriminated poorly between water and thaumatin or monellin. After miraculin they changed their strong rejection of 0.02 M citric acid, in a choice between water and acid, into a strong preference for the acid. These results show a close relation between the electrophysiological and the behavioural data.
Autonomic Nerve Control of the Swimbladder of the Goldsinny Wrasse,Ctenolabrus rupestris
Authors: Fänge Ragnar , Holmgren Susanne , Nilsson Stefan 
Published: December 2008

AbstractThe autonomic nerve control of the swimbladder of the goldsinny wrasse has been studied by experiments with isolated strips from the muscularis mucosae, drug effects on gas secretionin vivo, fluorescent histochemistry and quantitative analysis of catecholamine content. Vagotomy, atropine and mecamylamine significantly inhibited induced gas secretion, suggesting a cholinergic vagal secretory innervation of the gas gland. The anterior part of the mucosa (secretory part) is contracted by acetylcholine and α‐adrenoceptor agonists. These responses are competitively antagonized by atropine and phentolamine or yohimbine respectively. The posterior (resorbent) part of the mucosa is contracted by acetylcholine, but β‐adrenoceptor agonists relax the acetylcholine‐precontracted preparations. These responses are competitively blocked by atropine and propranolol respectively. The pA2‐values from all experiments with antagonists are well comparable with values obtained for the same drugs in other teleost or mammalian tissues. Tyramine, 5‐hydroxytryptamine or phenylephrine had mixed effects on the posterior part. This effect is at least in part due to release of nervously stored catecholamines. Fluorescent histochemistry revealed a strong innervation by both smooth and varicose adrenergic fibres in all parts of the swimbladder, noradrenaline being the dominant catecholamine. Yellow fluorescent cells, which may contain 5‐hydroxytryptamine, were also seen in the swimbladder mucosa. No conclusive evidence for a cholinergic innervation of the muscularis mucosae was obtained.