bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Method for Preparing Isolated Glands from the Rabbit Gastric Mucosa
Authors: Berglindh Thomas , ÖBrink Karl Johan 
Published: December 2008

AbstractA method for isolating gastric glands from the corpus of the rabbit gastric mucosa is presented. The stomach of an anesthetized rabbit was perfused with saline under high pressure through the aorta, taken out and emptied. The mucosa was stripped off, minced into small pieces and transferred to a 1 mg/ml collagenase solution. After 90 min at 37°C, a large number of isolated gastric glands and cells were separated free. By a simple washing procedure the glands were freed from cell contamination and collagenase. The gastric glands were viable, as demonstrated by dye exclusion technique, oxygen consumption and electrolyte content. For identification of the glandular cells both common staining techniques and electron microscopy were used. Four types of cells were identified, viz. parietal cells, zymogen cells, mucous neck cells and some endocrine cells. The intracellular morphology of the glandular cells did not differ significantly from that seen in intact gastric mucosa. The glands could be stimulated with histamine, in a dose‐response manner, as revealed by the increase in oxygen consumption (ED‐50 equal 3 × 10‐6 M). This isolated gastric gland preparation may serve as a useful tool for new approaches in gastric physiology.
Beta Adrenergic Dilator Component of the Sympathetic Vascular Response in Skeletal Muscle Influence on the micro‐circulation and on transcapillary exchange
Authors: Lundvall Jan , Järhult Johannes 
Published: December 2008

AbstractA neurogenic β‐adrenergic vasodilatation in skeletal muscle has been indicated by some recent investigations. The present study describes the extent to which this neurogenic β‐dilator mechanism contributes to the integrated vascular response in consecutive sections of the muscle vascular bed during sympathetic nerve activation. This was done by studying the vascular reactions to graded sympathetic stimulation (1–16 Hz) before and after β‐adrenoceptor blockade, β‐blockade did not influence significantly the sympathetically induced changes of total muscle vascular resistance or capacitance. Vascular tone in the “micro‐vessels” during stimulation was, however, clearly more pronounced in the β‐blocked than in the non‐blocked region, as revealed by segmental resistance analysis and by determination of precapillary sphincter tone (CFC). In addition, β‐blockade markedly reduced the net transcapillary absorption of extravascular fluid evoked by nerve activation. This effect could be ascribed to the mentioned influence on the precapillary sphincters, leading to a decrease of the number of capillaries available for transcapillary exchange, and to a limitation of the nerve induced fall of capillary hydrostatic pressure. The described effects of β‐blockade were observed at all rates of sympathetic stimulation. — The conclusion was reached that the β‐adrenergic dilator component of the sympathetic vascular response in skeletal muscle significantly modifies the α‐adrenergic constriction in the micro‐vessels. It is suggested that, in the intact organism, this neurogenic β‐dilator mechanism is primarily aimed at improving the transcapillary exchange.
Disturbances in Voluntary Recruitment Order of Low and High Frequency Motor Units on Blockades of Proprioceptive Afferent Activity
Authors: Grimby Lennart , Hannerz Jan 
Published: December 2008

AbstractThe voluntary recruitment order of anterior tibial motor units was studied in electromyographic recordings using both low and high impedance electrodes. It was shown in previous papers, that the recruitment order in sustained voluntary contraction is normally stable and that motor units with low thresholds discharge at low, regular frequencies and that motor units with high thresholds discharge at higher and more irregular frequencies. In this paper the consequences for the discharge properties of reduced afferent inflow in sustained voluntary contraction were studied, using partial ischemic or lidocain blockades of the muscle nerve and local cooling of the muscle belly. 1. The recruitment order of certain low and certain high frequency units was reversed. 2. The muscle tension and sense of effort necessary for tonic firing were increased for certain low frequency units but decreased for certain high frequency units. 3. On severe reduction of the afferent inflow, the differences in discharge pattern between low and high frequency units were decreased. It is concluded that the recruitment of low frequency units before high frequency units in sustained voluntary contraction is partly due to proprioceptive afferent activity favouring low frequency units and disfavouring high frequency units. It is also concluded that the afferent inflow is involved in restricting certain units to low frequency discharge and others to high frequency discharge.
Regional Distribution of Blood Flow in Calf Muscles of Rat during Passive Stretch and Sustained Contraction
Authors: Wisnes A. , Kirkebø A. 
Published: December 2008

AbstractThe regional distribution and number of microspheres in the calf muscles of rat has been studied during isometric sustained contraction and in stretched uncontracted muscles in situ. Carbonized microspheres, 15 ± 5 μm, were injected into the aortic arch and muscle blood flow arrested 6 sec later. The calf muscles were freeze sectioned (12 slices of 40μm) and the microspheres counted microscopically. The microsphere concentration in the gastrocnemius and plantaris muscles during rest was 4.6 ± 1.6 spheres/mm3 (mean ± S.E.). One min after a standardized exercise programme the sphere concentration was increased to 20.5 ± 3.9 spheres/mm3. At increasing force of contraction following the standard exercise programme, the microsphere concentration fell from 11.6 ± 2.5 at 25% of maximal force of contraction (MFC) to 2.2 ± 0.6 spheres/mm3 at 100% MFC (5.6 kg/cm2). Corresponding measurements in stretched, uncontracted muscles showed a similar fall in microsphere concentration when stretch was increased from 50 to 175% MFC. The ratio between microsphere concentration in the central inner zone and in the peripheral outer zone was slightly higher than unity (1.08‐1.16) in muscles at rest and at light postexercise hyperemia. At 75 and 100% MFC the ratio was 0.76 ± 0.07 and 0.57 ± 0.13, significantly lower than unity. Stretching of the uncontracted muscle group to 175% MFC reduced the ratio towards zero. The greater reduction in blood flow to the inner central zone of contracted calf muscles shown by microsphere distribution was confirmed by measurement of 125I‐antipyrine distribution. These results show an increased resistance against blood flow during active contraction or stretching of the calf muscles, most pronounced in the central inner zone at high tensions.
Effects of Lesions in the Parabrachial Nucleus on the Mechanisms for Central and Reflex Termination of Inspiration in the Cat
Authors: Euler C. von , Marttila Irja , Remmers J. E. , Trippenbach Teresa 
Published: December 2008

AbstractThe effects of PCO2 and body temperature on the time course and peak amplitude of the central inspiratory activity (CIA) and the inspiratory ‘off‐switch’ threshold was studied in apneustic and non‐apneustic cats. Apneusis resulted from lesions of the inspiratory inhibiting structures of the medial parabrachial nucleus (NPBM) and by interrupting vagal volume feedback. The cats were paralyzed and ventilated either proportionally to their phrenic output or at predetermined rate and volume. The dependence of the rate of rise and maximal amplitude of phrenic activity on PCO2, and body temperature were comparable in apneustic and non‐lesioned animals. The Hering‐Breuer volume threshold for inspiratory termination was increased following the rostral pontine lesions. Both hyperthermia and hypercapnia caused augmentation of the absolute rate of rise of inspiratory activity but hypercapnia, in contrast to hyperthermia, caused virtually no change in the fractional increment per unit time. With hypercapnia the inspiratory ‘off‐switch’ threshold was raised in the apneustic animals as in intact ones, whereas hyperthermia did not seem to influence this threshold. In apneustic conditions expiratory duration remained constant, independent of the large variations in the inspiratory durations. Our results suggest that the NPBM merely provides an excitatory, threshold‐lowering input to the inspiratory ‘off‐switch’ mechanism.
Temperature Effects on the Inflation Reflex during Expiratory Time in the Cat
Authors: Euler Curt von , Trippenbach Teresa 
Published: December 2008

AbstractIn order to obtain further information on the mechanisms controlling expiratory duration (TE) we have studied the effects of changes in body temperature on reflex characteristics of the TE‐prolonging inflation reflex. In cats under light pentobarbitone anesthesia controlled volume changes were applied at various times in expiration and the changes in TE were measured from records of phrenic activity. Inflations falling in the last 20% of the control expiratory time were without effect. This reflex insensitive phase remained a constant fraction of expiratory time when respiratory rate was changed with temperature. The relative reflex responsiveness increased, and the volume threshold was reduced with increasing respiratory rate. The inflation reflex characteristics showed integration of the incoming pulmonary stretch receptor activity. The integrating mechanism exhibited a ‘leaky’ character, the decay rate of which changed with body temperature. Functionally the duration of the inspiration‐inhibiting activity controlling expiratory duration can be regarded as dependent on 3 main factors 1) the initial peak level of the inhibitory activity, 2) the amount and timing of the vagal afferent activity which adds to this inhibition, and 3) its rate of decay. The results suggest that all these factors are influenced by changes in temperature.
Convergence on Interneurones Mediating the Reciprocal Ia Inhibition of Motoneurones
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. Volleys in ipsilateral and contralateral high threshold muscle afferents, cutaneous afferents and high threshold joint afferents evoked a mixture of polysynaptic excitation and inhibition. These effects were ascribed to pathways activated by flexor reflex afferents (FRA) and in addition a specific ipsilateral low threshold cutaneous pathway. Ia inhibitory interneurones excited monosynaptically from flexor nerves received stronger net excitation by volleys in ipsilateral FRA than did extensor coupled interneurones, while the opposite pattern was seen from the contralateral FRA. These patterns are similar to those found in flexor and extensor motoneurones respectively. The FRA inhibition in Ia inhibitory interneurones was partly mediated by “opposite” Ia inhibitory interneurones, i.e. those which are mediating the Ia inhibition of la inhibitory interneurones. The extent to which the FRA inhibition is transmitted by Ia inhibitory interneurones was roughly estimated by its susceptibility to recurrent depression by antidromic ventral root stimulation. The main conclusion is that most segmental pathways seem to evoke their effects in parallel to motoneurones and Ia inhibitory interneurones which are monosynaptically linked to the same muscle. The functional importance of this conclusion is discussed in a following report.
Inhibition by Reserpine, Guanethidine and Imipramine of the Uptake of 5‐Hydroxytryptamine by Rat Peritoneal Mast Cellsin Vitro
Authors: Gripenberg J. 
Published: December 2008

AbstractThe effect of reserpine, guanethidine and imipramine on the uptake of tritiated 5‐hydroxytryptamine by rat peritoneal mast cells was studiedin vitro.The Kmvalue for uptake of 5‐hydroxytryptamine was 3 × 10‐7M in this study. Kinetic analysis of the data obtained suggests that the drugs inhibit the uptake in a competitive manner, in the order of decreasing potency: reserpine, imipramine, guanethidine. For reserpine the Dixon plot resulted in two curves, each composed of 2 linear components suggesting inhibition of uptake of 5‐hydroxytryptamine at 2 different levels or by 2 different mechanisms with different K1values. It is suggested that the higher K1value, representing an immediate effect of reserpine, stands for inhibition of uptake at the cell membrane. The lower K1value possibly represents inhibition at the level of the membranes surrounding the intracellular storage organelles.
The Vagal Control of the Ileo‐Cecal Sphincter in the Cat
Authors: Pahlin P.‐E. , Kewenter J. 
Published: December 2008

AbstractIn acute experiments on chloralosed cats the effect of efferent cervical vagal stimulation on a flow through the ileo‐cecal sphincter (ICS) was studied. The motor activity of the jejunum, ileum and large intestine adjacent to the sphincter was recorded simultaneously. Vagal stimulation caused a decrease in the transsphincteric flow and increased motor activity in the ileum. Increased motor activity in the proximal colon was recorded only occasionally. When the vagal nerves were stimulated during continuous splanchnic stimulation the transsphincteric flow was decreased although the tone and motility of the ileum was supposed. Furthermore, guanethidine (1–3 mg/kg b.w.) blocked or suppressed the effect of vagal stimulation on the transsphincteric flow while the excitatory response of the proximal colon was greatly enhanced. This indicates that the reduction of the transsphincteric flow following vagal stimulation was at least partly due to a direct effect of the vagal nerves on the sphincteric muscle and not to a squeezing effect of that part of the colonic wall that surrounds the sphincter. Atropine (0.1 and 1 mg/kg b.w.) blocked all responses to vagal stimulation. Thus, both guanethidine and atropine blocked the vagally induced contraction of the ICS. Relaxation of the ICS was never obtained by vagal stimulation even when the tone of the sphincter had been increased by infusion of noradrenaline.
Effects of Lanthanum on Pinocytosis Induced by Cations inAmoeba proteus
Authors: Josefsson J.‐O. , Hansson S. Elisabeth 
Published: December 2008

AbstractLanthanum chloride (≥ 10‐5M) induced pinocytosis in normal and at ≥10‐4M in Ca++‐deficient amoeba. With respect to the Ca++‐requirement of the pinocytotic response low and high concentrations of La+++had effects like Na+and K.+, respectively. The concentration of La+++and the concentration and species of inducing monovalent cation determined whether La+++stimulated or inhibited other types of pinocytosis. Thus all concentrations of La+++inhibited sodium induced pinocytosis while high concentrations (> 10‐3M) stimulated and low concentrations diminished potassium induced pinocytosis. Only the latter effect required the presence of Ca++. In the presence of La+++other inducers acted either like K+or Na+. Inducers may cause channel formation by opening a pore for Ca++in the plasma membrane, Na+‐like inducers being less effective than K+‐like inducers, and by releasing Ca++into the cytoplasm from the glycocalyx (Na+‐like inducers) or from the entire cell membrane (K+‐like inducers). La+++may diminish the effect of Na+‐like inducers and vice versa by direct competition for sites in the glycocalyx and the effect of K+‐like inducers by redistribution of Ca++in the cell surface. At high concentrations or in the presence of a K+‐like inducer La+++may enter the Ca++pore, release Ca++from the interior of the membrane and so induce or stimulate pinocytosis.
The Effect of Local Application of Vinblastine or Colchicine on Acetylcholine Accumulation in Rat Sciatic Nerve1
Authors: Heiwall P.‐O. , Saunders N. R. , Dahlström A. , Häggendal J. 
Published: December 2008

AbstractThe accumulation of acetylcholine (ACh) following nerve crush was inhibited by high concentrations of colchicine (10‐1, 10‐2 M) and vinblastine (10‐2‐10‐4 M) in a dose‐dependent manner. The two mitotic inhibitors were effective both when applied to axons (subepineural injections) and to perikarya (injections into the lumbar intumescence). The results indicate that mitotic inhibitors, when applied locally to cholinergic motor neurons, may block the proximo‐distal transport of ACh. The possibility is discussed that this blockade is caused by an interference with a microtubule mechanism in the axons. Evidence for an increased local synthesis of ACh near the site of injection into nerves was also obtained with the highest concentrations of either substance used.
Release of Vitamin B12‐Binding Protein from Isolated Rat Liver Perfused with a Synthetic Medium
Authors: Nováková Vera , Gullberg Ragnhild 
Published: December 2008

AbstractThe unsaturated vitamin B12‐binding capacity (UBBC) of the small molecular size vitamin B12‐binding protein (SBP) release and albumin release into the medium and the fluid pressure in the portal vein were studied with respect to their ability to reflect the state of isolated perfused rat liver. The liver was perfused in vitro with a synthetic medium either with or without a gas carrier. Liver damage was induced by hypoxia or noradrenalin. Variations in experimental conditions resulted in different patterns of parameters reflecting different aspects of the liver state. The fluid pressure in the portal vein reflected sensitively the circulatory state but is not always a criterion of the general condition of the isolated liver. The albumin release is a criterion of functional state but did not always reflect liver damage. However, the amount of UBBC of SBP released into the medium is a parameter reflecting sensitively the functional capacity of the liver to produce protein and also seems to indicate liver damage. The use of this parameter provides supplementary information that cannot be obtained by either of the two more conventional parameters.
Motor and Secretory Effects of Nerves on the Parotid Gland of the Rat
Authors: Thulin Anders 
Published: December 2008

AbstractThe influence of parasympathetic and sympathetic nerves on the parotid gland of the rat was investigated. It was found that both divisions of the autonomic nerves evoke secretion and probably also motor effects in this gland. Secretion elicited on sympathetic stimulation was mediated both via α‐ and β‐adrenoceptors, while motor effects were mediated via α‐adrenoceptors. On stimulation of the autonomic nerves a lower duct pressure was reached in the parotid than in the submaxillary gland, and on sympathetic nerve stimulation the flow of saliva always started later from the parotid than from the submaxillary gland. These findings are discussed in the view of the different arrangement of the myoepithelial cells in the 2 glands.
Anin vitro‐Formed Protamine‐Heparin Complex as a Model for a Two‐Compartment Store for Biogenic Amines
Authors: Uvnäs Börje , ÅBorg Carl‐Hugo 
Published: December 2008

AbstractThe capacity of anin vitro‐formed protamine‐heparin complex (PHC) to store inorganic cations and biogenic amines was investigated. The PHC behaves like a two‐compartment storage system. One compartment corresponds to the terminal free carboxyl groups of the protamine moiety and has the characteristics of a cation exchanger, with the ability to bind inorganic cations and biogenic amines in a reversible and rather unselective manner. The cations and biogenic amines therefore compete for and displace each other from the common ionic binding sites. The binding sites in the other compartment, corresponding mainly to the carboxyl groups of the heparin moiety, are only unmasked at high ionic concentrations and show a specific affinity for biogenic amines. The storage of amines in this compartment of the PHC is reversible but is dependent not only on simple ionic binding but evidently also on other attractive forces, such as dipole and hydrogen bonding.
Gravitational Stress and Autonomic Cardiac Blockade
Authors: Bjurstedt H. , Rosenhamer G. , Tydén G. 
Published: December 2008

AbstractArterial pressure, heart rate and cardiac output were recorded in eight healthy, male volunteers in the sitting position at normal gravity (1 G) and during a 4 min exposure in a human centrifuge to 3 G, the G vector in both conditions acting in the head‐foot direction. The responses of the observed variables to the change from 1 G to 3 G were compared before and after combined beta‐adrenergic and parasympathetic blockade of the heart induced by the i.v. administration of propranolol, 0.25 mg/kg bwt, and atropine, 0.03 mg/kg bwt. After blockade the heart‐rate response to increased G averaged 22% of that observed without blockade. Mean arterial pressure at 3 G, and thus G tolerance, was significantly lowered after blockade, resulting in symptoms of retinal hypoxia (“greyout”) towards the end of the 3 G runs in some of the subjects. G‐induced reductions in cardiac output and stroke volume were significantly larger after blockade. Associated increases in total peripheral resistance were 56% before and 79% after blockade, the stronger vasoconstrictor response in the latter case thus being insufficient for maintenance of arterial pressure homeostasis.
Interaction between the Hypothalamic Defence Reaction and Cardiac Ventricular Receptor Reflexes
Authors: Wennergren Göran , Lisander Björn , ÖBerg Bengt 
Published: December 2008

AbstractThe interference with regard to the cardiovascular and gastric motility responses which follows stimulation of the hypothalamic defence area (D.A.) and a simultaneous afferent input from cardiac ventricular receptors was analysed in chloralose‐anesthetized cats. In spinalized animals with only the vagal efferent innervation of autonomic effectors from supraspinal structures intact, a D.A. stimulation increased the heart rate to the same level irrespective whether the cardiac receptor afferents were stimulated or not. This suggests that the vagal component of the reflex bradycardia of cardiac receptor origin was completely suppressed by the D.A. stimulation. The reflex gastric relaxation to cardiac receptor activation, mediated via vagal efferent non‐adrenergic fibres, was similarly completely blocked by D.A. stimulation. In contrast, the reflex inhibition of the sympathetic outflow to the heart and vessels from cardiac receptors was still effective during a D.A. stimulation, a phenomenon which seems compatible with a simple summation of excitatory D.A. and inhibitory cardiac receptor influences on the sympathetic neurons. The modifying influence from ventricular receptors on D.A. responses closely resembles that exerted by the arterial baroreceptors. The two reflex mechanisms thus work in concert and synergistically with the hypothalamic influences to produce maximal cardiac output and skeletal muscle perfusion without undue increases of pressure load on the pump during a defence reaction.
The Effects of Neuraminidase and Protamine Chloride on Potential Clamp Parameters of the Node of Ranvier (Xenopus laevis)
Authors: Frankenhaeuser B. , Ryan K. J. , ÅRhem P. 
Published: December 2008

AbstractThe effects of neuraminidase and protamine chloride on the ionic currents associated with step changes in membrane potential were studied. Neuraminidase (a hydrolase which cleaves glycosidically bound sialic acid) had negligible effects on the permeability properties. The polycation protamine chloride decreased the sodium as well as the potassium currents. The sodium equilibrium potential decreased during the experiments which indicates a gain in internal sodium concentration. The analysis showed that the effects on the currents were caused by a decrease of the specific permeability changes. No shift along the potential axis of the potential dependent parameters was observed.