bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glucose Consumption in Rat Cerebral Cortex in Normoxia, Hypoxia and Hypercapnia
Authors: Borgström L. , Norberg K. , Siesjö B. K. 
Published: December 2008

AbstractGlucose consumption was measured in the cerebral cortex of rats, anesthetized with 70% N2O, under normoxic conditions, as well as in hypoxia (Pao2 about 25 mmHg) and hypercapnia (Paco2 80–85 mmHg). The method used was that of Hawkins et al. (1974), modified to allow studies of transients in glycolytic rate. Cortical glucose consumption in normoxia was 0.77 μmol·g‐1·min‐1. It is concluded that whereas glucose consumption in the whole brain of the unanesthetized rat may be close to 0.6 μmol·g‐1·min‐1, that of the cerebral cortex is close to 0.8μmol·g‐1·min‐1. During the first 2 min of hypoxia, glucose consumption was increased to twice the normal, and during the first 2 min of hypercapnia, the corresponding value was less than one third of the normal. After 15 min of hypoxia, the glucose consumption had returned towards control values. In “steady state” hypercapnia, the glycolytic flux was higher than in the initial phase although still below normocapnic values.
Protein Synthesis with Special Reference to S‐100 Protein in Brain Slices from Rats Receiving a Restricted Protein Supply
Authors: Wroński Andrzej , Decken Alexandra von der 
Published: December 2008

AbstractThe synthesis of S‐100 protein and that of soluble and total proteins was investigated using cerebral slices from rats fed a 20% or 3% protein containing diet for 6 days. Incorporation of radioactive amino acids into S‐100 protein was significantly higher when rats were fed a diet containing 20% protein. No significant differences were obtained in the radioactivity incorporated into total or soluble proteins between the 2 dietary groups. 14C‐leucine of a specific radioactivity of 55 mCi/mmol or 3.2 mCi/mmol incorporated with time into total protein was similar for the 2 dietary groups. The time‐dependent uptake of 14C‐leucine by the slices and the inulin space remained unaffected by the dietary conditions used; and amino acid analyser estimates of the free amino acid pool showed no significant differences. Brain wet weight was 1.54 ± 0.02 g and 1.39 ± 0.02 g for protein‐fed and protein‐restricted rats respectively. The corresponding body weight increased by 7.8 g/day or fell by 0.5 g/day. Although the differences observed in total protein synthesis were small the synthesis of a nervous tissue specific protein S‐100 was markedly affected by short‐term protein restriction.
Oxygen Uptake and Tissue Oxygen Tension during Adrenergic Stimulation in Canine Subcutaneous Adipose Tissue
Authors: Fredholm Bertil B. , Linde Birgitta , Prewitt Russell L. , Johnson Paul C. 
Published: December 2008

AbstractThe effect of sympathetic nerve stimulation (NS) and injected noradrenaline (NA) or isoprenaline (Iso) on PvO2, V̇osand PtO2was studied in isolated canine subcutaneous adipose tissue. These effects were compared to those produced by mechanical blood flow reduction (clamping). Resting V̇o2measured 13.0 ± 2.3 μmol × min‐1× 100 g‐1. When blood flow was reduced by 20% or less there was no significant change of V̇o2. Reducing blood flow to 50% of control or less by NS caused a parallel reduction in V̇o2, while clamping reduced V̇o2significantly less. NA gave effects similar to those of NS. After NS or NA there was a period of hyperemia and increased oxygen extraction which more than compensated for the decrease in V̇o2during vasoconstriction. Such a net increase in V̇o2was not produced by clamping. Control PtO2averaged 29±2 mmHg. NA reduced it by 70% and clamping to the same blood flow level only by 14% (p<0.01). Thus, a mere reduction in blood flow has little effect on PtO2, while blood flow reduction combined with redistribution of blood flow and an increased oxygen demand can lead to tissue hypoxia.
Prediction of Propagation Block on the Basis of Impulse Shape in Single Unit Recordings from Human Nerves
Authors: Vallbo Å. B. 
Published: December 2008

AbstractThe occurrence of impulse block was studied in single unit recordings and related to impulse shape when peripheral nerves were impaled with tungsten needle electrodes. Exposed nerves were exploited in frog and cat and non‐exposed nerves in man. Three different impulse shapes were seen: 1. Negative spikes of very short durations which nearly all propagated. 2. Positive double peaked spikes which all propagated. 3. Positive single peaked spikes which were of two different natures: one which propagated and one which did not. The findings suggest that unitary impulses recorded with a needle electrode impaling the myelin are positive and single peaked when the injury is minimal. Gradually a propagation delay might develop at the site of impalement giving rise to a double peak. Later the propagation may be blocked which is seen as a drop out of the second peak. The collected sample of observations indicates that it was possible to predict in practically all cases whether the propagation was blocked or not from the shapes of the single unit impulses and their alterations as seen by the tungsten needle electrode.
Effect of Vasodilating Drugs on External Carotid and Pulpal Blood Flow in Dogs: “Stealing” of Dental Perfusion Pressure
Authors: Tönder K. J. H. 
Published: December 2008

AbstractBlood flow in the external carotid artery (ECBF) and dental pulp (PBF) was measured during arterial infusion of vasodilators (isoprenaline, papaverine, acetylcholine and bradykinin). Systemic arterial pressure (AP) and local arterial pressure of the teeth (LAP) were recorded in a femoral and the lateral nasal artery respectively. All four vasodilators were found to increase ECBF and simultaneously reduce lateral nasal arterial pressure—or in other words—to “steal” perfusion pressure from the teeth. AP remained practically unchanged whereas PBF was variably affected. During infusion of isoprenaline PBF decreased on average by 19% of control. Papaverine nearly doubled PBF, while bradykinin caused no consistent change. Great pulpal flow variations were often recorded during constant acetylcholine infusion rate. The variable effect of the four vasodilators on PBF could partly be explained by the fall in LAP. Calculated pulpal resistance (LAP/PBF) showed no consistent change during isoprenaline infusion, bradykinin caused a slight fall and papaverine reduced LAP/PBF by 49%. The experiments demonstrate that due to the “stealing” of dental perfusion pressure caused by vasodilation in the neighbouring tissues, the effect of vasodilators on pulpal resistance vessels cannot be estimated without knowledge of the pressure in the small arteries directly feeding the teeth.
β2‐Adrenoceptors Facilitating Noradrenaline Secretion from Human Vasoconstrictor Nerves
Authors: Stjärne Lennart , Brundin Jan 
Published: December 2008

AbstractIsolated superfused biopsy specimens of human peripheral arteries and veins, preincubated with 3H‐(‐)‐noradrenaline (NA) to label the neural stores of NA, were used to study the β‐adrenoceptors previously found to increase the secretion of 3H‐NA evoked by electrical field stimulation of the adrenergic nerves of this tissue. The increase in nerve stimulation induced secretion of 3H‐NA caused by 0.04μM isoprenaline was prevented by 1 μM propranolol. This &bT‐blocking drug by itself slightly but significantly depressed the secretion of 3H‐NA caused by nerve stimulation in the absence of isoprenaline. While the secretion of 3H‐NA was not affected by two known β1‐agonists, it was dose‐dependently and reversibly increased by two different β2‐agonists. The effect of isoprenaline on 3H‐NA secretion was not altered by a selective β‐antagonist, but strongly reduced or abolished by a β2‐blocking drug. The results indicate that the β‐adrenoceptors involved in the control of NA secretion from the vasoconstrictor nerves of human omental blood vessels are only to a minimal extent stimulated by NA secreted from the nerves, and therefore do probably not mainly serve to mediate local positive feedback control of transmitter secretion; the receptors appear to be β2 in nature.
Vagal Reflexes in the Bronchoconstriction Occurring after Induced Intravascular Platelet Aggregation
Authors: Vaage Jarle 
Published: December 2008

AbstractIntravascular platelet aggregation induced in cats by i.v. infusions of collagen caused a transient increase in pulmonary vascular resistance (PVR) and in non‐elastic pulmonary resistance (RL), and a transient decrease in dynamic lung compliance (dyn CL). PVR, dyn CL and platelet aggregation after collagen infusions were unaffected by bilateral cervical vagotomy and atropinization, whereas these procedures reduced the post‐infusion rise in RL by about 50 per cent. The administration of indomethacin inhibited platelet aggregation as well as bronchoconstriction after collagen infusion. The present investigation indicates that intravascular platelet aggregation will cause reflex bronchoconstriction mediated by vagal efferent fibres.
The Origin of Impulses Recorded from Dentinal Cavities in the Tooth of the Cat
Authors: Haegerstam G. 
Published: December 2008

AbstractIntradental nerve impulse activity can be recorded by means of electrodes inserted into dentinal cavities in the tooth of the cat. The following study has been conducted to investigate the origin of this impulse activity. The results suggest that the fibres from which the impulses are recorded must pass through the major part of the pulp between the recording electrodes. Furthermore, the results show that it is not possible to record discharges in the finest terminal branches in the pulpo‐dentinal border zone using the present technique. However, the data obtained indicate that these terminal branches were activated during stimulation resulting in recordable propagated axonal impulses.
Metabolic Reactions to Changes in Core and Skin Temperature in Man
Authors: Nielsen Bodil 
Published: December 2008

AbstractThe metabolic cold response, i.e. the increase in oxygen consumption above that for the given activity in a neutral environment, was measured in 7 subjects during cooling, resting or swimming in cold water (14, 16, 18, 20°C) and during rewarming in air (Ta 20, 30, 40°C), bicycling or resting. Esophageal temperatures varied between 38 and 34°C. Mean skin temperature was considered as equal to water temperature during cooling, and ranged between 25–35°C during rewarming in the different environments. Both central and peripheral cold stimulation induced metabolic cold responses. The skin temperature was the dominating factor in determining the response, especially in transient states. During rewarming a rising skin temperature suppressed the effects of even very low core temperatures.
The Role of Cholinergic Excitation in the Formation of Histamine within the Rat Gastric Mucosa
Authors: Lundell Lars 
Published: December 2008

AbstractIn the absence of the antrum, central vagal excitation and distension of the stomach accelerated the rate of formation of gastric mucosal histamine. The effect of vagus stimulation was abolished by truncal vagotomy or atropine whereas that of distension by atropine. After truncal vagotomy, distension was still effective in accelerating the formation of the amine. Furthermore, mucosal histamine formation in the fasting state was reduced by truncal vagotomy and atropine injection.
Effects of Respiratory Alkalosis and Acidosis on Myocardial Excitation
Authors: Samuelsson Rolf G. , Nagy György 
Published: December 2008

AbstractIn anesthetized dogs electrocardiogram and monophasic action potentials (MAPs) were recorded from the right atrium and the right ventricle by intracardiac suction electrode technique. The animals were subjected, by means of ventilation with CO2 and hyperventilation, to periods of respiratory acidosis and respiratory alkalosis, respectively. Pronounced respiratory acidosis induced an increased sympathetic activity followed by a decrease in heart rate and prolongation of the A‐V conduction time whereas the shape and duration of the atrial and ventricular MAPs remained unaltered. Arterial hypoxia in combination with pronounced respiratory acidosis did not influence the MAP durations. Respiratory alkalosis resulted in an increased sympathetic influence on the heart activity whereas the shape and duration of the atrial and the ventricular MAPs remained unaffected. During pronounced hyperventilation with increasing central venous pressure an increased parasympathetic influence on the heart activity with decrease in the heart rate, prolongation of the A‐V conduction time and shortening of the atrial MAP duration was recorded.
Effect of Sympathetic Nerve Stimulation on Net Transvascular Movement of Fluid in Canine Adipose Tissue
Authors: Linde Birgitta 
Published: December 2008

AbstractNet transvascular movement of fluid has been studied in the isolated, autoperfused subcutaneous adipose tissue of the dog, during and after sympathetic nerve stimulation (1–15 Hz) and during infusion of 50% glucose i.a. Net fluid movement was calculated as the difference between change in tissue volume and change in blood volume. Tissue volume was measured by plethysmography and blood volume by external monitoring of circulating131I‐albumin. No net fluid movement of statistical significance was found during or after nerve stimulation except during the first minute of stimulation at 15 Hz when a small net absorption (p<0.05) was obtained. In contrast, infusion of glucose at 25–75 mOsm/kg H2O produced a dose‐dependent net absorption lasting several minutes, amounting maximally to 0.30 ml × min‐1× 100 g‐1. The absence of prolonged net absorption in subcutaneous adipose tissue during nerve stimulation as well as the absence of net filtration after stimulation may be explained by an essentially unaltered mean hydrostatic capillary pressure. The results indicate that adipose tissue does not contribute to the fluid homeostasis of the body via sympathetic resetting of the pre‐postcapillary resistance ratio. Thus, mobilisation of fluid from the nterstitial space in adipose tissue into the blood does not seem to occur by nerve activity.
Effect of the H2‐Receptor Antagonist Metiamide on Carbachol‐and Histamine‐Induced Gastric Acid Secretion in the Atlantic Cod, Gadus morhua
Authors: Holstein Björn 
Published: December 2008

AbstractGastric acid secretion was measured in swimming codfish surgically equipped with a catheter draining the stomach. Intramuscular injection of histamine (15.6μg/kg·h) or carbachol (5μg/kg·h) stimulated the secretion of acid, carbachol in addition caused a marked decrease in drinking rate of the fishes. Administration of 10μmol/kg·h metiamide completely prevented the acid secretion induced by both drugs. The carbachol effect on the drinking rate, interpreted to mirror contraction of the stomach following stimulation of muscarinic receptors, was not affected by metiamide.
Influence of Altered CSF Solute Composition on Parotid Salivary Secretion in Goats
Authors: Olsson Kerstin 
Published: December 2008

AbstractInfusions of hypertonic NaCl solution into the CSF of the lateral cerebral ventricle of the goat caused a marked reduction in parotid salivary flow concomitant with a rise in salivary [Na+]. Corresponding infusions of iso‐ or hypertonic glucose and glycerol solutions affected salivary secretion in the opposite direction. The possibility is discussed that a periventricular sodium‐sensitive mechanism, which is of importance in the central control of fluid balance, also may participate in the regulation of parotid secretion in the goat. This interpretation of the results is to some extent obscured by the observation of a high incidence of intermittent rumination during the intraventricular infusions of glucose and glycerol solution.
K+Transport in Isolated Rat Liver Cells Stimulated by Glucagon and Insulin in vitro
Authors: Berg Trond , Iversen Jens‐Gustav 
Published: December 2008

AbstractUnidirectional K+fluxes were measured in suspensions of isolated rat liver parenchymal cells incubated with 42K+in vitro. By tracer exchange analysis fluxes in both directions were estimated to 8–9 10‐12mol/cm2. Glucagon in concentrations above 2 × 10‐8M increased both influx and efflux to 160% of control values. Insulin increased influx by 12–14 %, whereas efflux was apparently unaffected. Using an extracellular marker 51Cr EDTA, intracellular level of some ions was estimated in isolated liver cells: K+= 172 mmol/kg water, Na+= 25 mmol/kg water, CI = 53 mmol/kg water. Cellular water content: 60%. Incubation with insulin for 1 h increased the intracellular concentration of K+1.7 mmol/kg water. The results indicate that glucagon increases primarily the K+‐permeability of the cell membrane, while insulin stimulates active K+transport into the cell.
Sources of Carbon Skeleton of Alanine Released from Skeletal Muscle
Authors: Spydevold Ø. 
Published: December 2008

AbstractThe formation of alanine, glutamate, and aspartate from muscle was studied in the isolated perfused hind‐quarter of rats fasted for 48 h. Tracer doses of (14C) compounds with high specific activity were tested as precursors for the amino acids. Total amounts and radioactivities of the tested amino acids were determined. Alanine was produced more efficiently than glutamate and aspartate even if no exogenous substrate was offered. (14C) Pyruvate was most efficient as precursor of labeled alanine. However, labeled leucine, propionic acid, valine and fumaric acid also produced labeled alanine efficiently. The efficiency as precursor for labeled alanine seemed to be related to the ability to label intermediates in the citric acid cycle in the perfused muscle. From the relation between the ability to label alanine in the perfusion medium and lactate and succinate in the muscle it is suggested that pyruvate may be produced intramitochondrially and is efficiently transaminated to alanine in this compartment.
Muscle Spindle Control during Locomotor Movements Generated by the Deafferented Spinal Cord
Authors: Sjöström Anders , Zangger Peter 
Published: December 2008

AbstractIn acute spinalized (Th 12) cats, treated with DOPA, curarized or with all lumbosacral dorsal roots transected, stepping patterns were elicited in the hindlimbs by continuous electrical stimulation of the dorsal roots. Single primary endings in dorsal root filaments or single γ and α efferents in muscle nerve filaments from flexors and extensors were recorded together with the efferent nerve activity to various hindlimb muscles. The experiments showed a clear coactivation of the intra‐ and extrafusal system to the same muscle. The α efferent discharges typically started with a very short first interspace interval. It is concluded that there exists a central spinal α‐γ‐Iinkage for locomotion in the hindlimbs.
The Effect of Nicotine on Intra‐Axonal Transport in Cholinergic Motor Neurons of the Rat; Influence of Acutely Administered, Non‐Toxic Doses
Authors: Heiwall P.‐O. , Dahlström A. , Larsson P.‐A. 
Published: December 2008

AbstractThe intra‐axonal transport of acetylcholine (ACh) and ACh‐metabolizing enzymes in rat sciatic nerves was studied following nicotine treatment. The nicotine was administered in a low dose (30;μg/kg) s.c. every second h for 18–22 h, to mimic the serum‐concentrations of a cigarette smoker. Control rats received s.c. injections of the vehicle. The main effects were observed regarding the ACh‐esterase (AChE) activity. In unoperated nerves the level was decreased by about 10%. In 12 h crushed nerves the accumulation of enzyme activity proximal to the crush was markedly reduced in the nicotine‐treated group, indicating a reduction in amount of proximo‐distally transported enzyme activity. The ACh‐levels were unchanged except at 12 h postoperatively when a small increase proximal to the crush was observed. The choline‐acetyltransferase (CAT) activity in unoperated nerves was similar in both groups of rats; the 7 h accumulation above the crush, however, was somewhat reduced after nicotine treatment. The possible causes of the observed nicotine induced changes are so far not known.
Influence of Acidosis on Noradrenaline‐Induced Vasoconstriction in Adipose Tissue and Skeletal Muscle
Authors: Hjemdahl Paul , Fredholm Bertil B. 
Published: December 2008

AbstractVasoconstriction due to parallel i.a. injections of NA were studied in subcutaneous adipose tissue and gracilis muscle preparations in dogs. The vasoconstrictor response to NA was significantly lower in adipose tissue than in muscle. Only in muscle did acidosis inhibit NA‐induced vasoconstriction. The β‐receptor antagonist propranolol increased the vasoconstrictor response in adipose tissue to the level of skeletal muscle. The lack of significant inhibition of NA‐induced vasoconstriction in adipose tissue may be due to the simultaneous inhibition of two opposing mechanisms‐α‐adrenergic vasoconstriction and β‐adrenergic vasodilatation. After propranolol acidosis inhibited NA‐induced vasoconstriction equally in adipose tissue and muscle. The difference between adipose tissue and muscle may thus be due to a greater importance of a β‐adrenergic vasodilator mechanism in the former tissue. The metabolic response to isoprenaline was inhibited by acidosis, while the direct vasodilatation was unaffected. It is suggested that the β‐adrenergic vasodilator mechanism that is inhibited by acidosis is related to the metabolism of the tissue.
Exteroceptive Influences on the Lumbar Back Muscle Tone and Reflexes in the Cat
Authors: Carlson Hans , Lindquist Christer 
Published: December 2008

AbstractThe exteroceptive influences on tonic activity and on stretch reflexes of the longissimus dorsi and multifidus spinae muscles were investigated in decerebrate, spinal and chloralose‐anesthetized cats. Adequate skin stimulation was used to map out facilitatory and inhibitory skin areas on the trunk and the extremities. On the trunk facilitatory areas are relatively large and located at the dorsal side while inhibitory areas are confined to the ventrolateral part of the contralateral body half. The facilitatory skin fields are of approximately the same size in decerebrate and spinal cats. On leg skin stimulation facilitation can be evoked from the ipsilateral hind limb while inhibition results from stimulation of the other limbs. Spinal cord transection increased excitatory effects of ipsilateral hind limb stimulation. Reflex responses in the back muscles to applied stretch are described. These reflexes were used as test reflexes in experiments with conditioning stimulation of the peripheral nerves supplying skin areas from which effects on back muscle activity were evoked by adequate stimulation. The conditioning‐test experiments and those using adequate stimulation show that the longissimus dorsi and multifidus spinae are activated or facilitated by an ipsilateral stimulus to skin afferents. The extent of the effects induced by stimulation of skin differs in the types of preparation used. These differences may be accounted for by assuming a supraspinal control of the reflex pathways studied.
Secretory and Motor Effects in the Submaxillary Gland of the Rat on Intraarterial Administration of Some Polypeptides and Autonomic Drugs
Authors: Thulin Anders 
Published: December 2008

AbstractBradykinin, oxytocin, physalaemin and some autonomic drugs were injected into the common carotid artery. Physalaemin evoked secretion and a pressure rise in the submaxillary duct. A duct pressure rise could be elicited by bradykinin which did not evoke secretion. Autonomic blocking agents did not diminish secretion evoked by physalaemin and did not change pressure responses elicited by bradykinin or physalaemin. Neither secretion, nor duct pressure changes could be recorded after administration of oxytocin. In agreement with previous experiments secretion evoked by autonomic drugs was found to be mediated via cholinergic, α‐ and β‐adrenergic receptors, while motor effects were due to activation of cholinergic and a‐adrenergic receptors.