bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reflex Adrenergic Inhibition of Gastric Motility Elicited from the Gastric Antrum
Authors: Abrahamsson Hasse 
Published: December 2008

AbstractThe reflex effects of distension and contraction of the gastric antrum on corpus‐fundus motility were studied in anesthetized cats. Besides a vagally mediated reflex corpus‐fundus relaxation, antral distension elicited a prompt reflex inhibition of corpus‐fundus contractions that was present also after vagotomy. In vagotomized animals this inhibitory reflex persisted also after cervical spinal cord transection, but was abolished by spinal anrsthesia or by guanethidine. Stepwise increases of antral distension revealed that the reflex corpus‐fundus inhibition appeared already at distending pressures of 5–10 cm H2O, then increased in a graded fashion and could be maintained for at least 10 min if a steady distension was applied. Also “isometric” antral contractions were effective in eliciting the reflex corpus‐fundus inhibition. — It is concluded that activation of slowly adapting “tension receptors” in the antral gastric wall inhibits gastric (corpus‐fundus) motilityviaa spinal reflex mechanism, mediated by splanchnic adrenergic fibres that seem to suppress the intramural excitatory cholinergic neurons. This gastro‐gastric adrenergic inhibitory reflex seems to be activated concomitantly with a vago‐vagal gastro‐gastric relaxatory reflex. It is suggested that these two suppressive reflex mechanisms play an important role in regulation of gastric motor functions.
Response of Isolated Frog Muscle Spindle to Sine Wave Stimulation
Authors: McReynolds J. S. , Ottoson D. 
Published: December 2008

AbstractThe impulse response and the receptor potential 01 the isolated muscle spindle of the frog were recorded during sinusoidal stretching at frequencies from 0.1 c/s to 100 c/s. Attention was focused on the changes of the responses in the initial phase of stimulation before the steady state was reached. In the course of sine wave stimulation the impulse response of the spindle undergoes regular changes characterized by an increase in threshold and latency of the individual impulses, a decrease in phase lead and peak frequency and a reduction in number of spikes in each cycle. The changes are most pronounced during the first 2–5 cycles, and a steady state with a fixed impulse patterning is usually reached after 10–15 cycles. The receptor potential evoked by a sine wave stretch is distorted in comparison with the waveform of the stimulus in having a relatively faster rise and slower decay. With changes in frequency and amplitude of stimulation it undergoes characteristic alterations in phase lead and configuration. When superimposed upon a constant stretch or a linearly rising stretch, sinusoidal stimulation produces responses which increase in amplitude with the underlying stretch. These observations provide evidence that the sensory endings responsible for the transducer action do not obey linear transfer functions.
Absorption from the Ambient Water and Combustion of Ethanol in Young Atlantic Salmon (Salmo salar L.) at Different Temperatures
Authors: Höglund Lars B. , Pilström Lars , Sjöblom Mats 
Published: December 2008

AbstractAfter 5–10 h exposure in static bio‐assays first‐summer Salmo salar live in equilibrium with the ambient ethanol concentration of 117 mmol/1 at 10° and 16° C. At 4° C this equilibration is retarded and is not evident until after 24 h. A quantitative connection between ethanol oxidation (M) and body weight (W) in accordance with the general formula M = K × Wb seems to exist for young salmon at 16° C. From the present tests the numerical values of the constants K and b were estimated to be approximately 10.5 and ‐1.03 respectively. Changes in behaviour induced by ethanol and the influence of temperature upon the metabolism of ethanol are discussed briefly.
Prostaglandin Action on Noradrenaline Release and Mechanical Responses in the Stimulated Guinea Pig Vas Deferens
Authors: Hedqvist Per 
Published: December 2008

AbstractPGE1and PGE2reversibly and dose‐dependently inhibited transmitter release from the stimulated guinea pig vas deferens. The two compounds proved equiactive and more prone to inhibit transmitter release at a low than at a high stimulation frequency. The PGEs inhibited the twitch response but produced inconsistent effects on contractions induced by prolonged stimulation. The difference may be due to the fact that the PGEs reduce the excitatory junction potentials and depolarize the effector cell membrane. Phenoxybenzamine increased transmitter release in response to nerve stimulation but failed to significantly alter the inhibitory effect of PGE2. It is therefore concluded that PGEs and presumed presynoptic α‐receptors probably intrude upon different levels of the process of excitation secretor, coupling. A possible model for the action of locally formed PGEs on the neuromuscular transmission of the vas deferens is advanced.
Effects of Lanthanum on Potassium Contractures of Isolated Twitch Muscle Fibres of the Frog
Authors: Andersson K.‐E. , Edman K. A. P. 
Published: December 2008

AbstractThe effects of lanthanum on the time course of potassium‐induced contractures of isolated muscle fibres from the frog were investigated. Two kinds of effects could be distinguished: 1. A reduction in the rate of tension development and a decrease in contracture amplitude; 2. A prolongation of the tension plateau and a decrease in the rate of relaxation during sustained depolarization. The effects under point 1 were obtained at lanthanum concentrations ≥ 0.5 mM, while those under point 2 were clearly visible at lanthanum concentrations as low as 0.01 mM. In a calcium‐free medium containing 0.1 mM lanthanum, a muscle fibre produced repeatable contractures to 117.5 mM potassium over many hours. The slowing of tension development and the diminished contracture amplitude is explainable on the basis of a reduction in the rate of release oi activator calcium in response to a depolarization step. The prolongation of the platmu and the slowing of relaxation caused by lanthanum is interpreted as reflecting a reduced rate of inactivation of thc calcium‐release mechanism following depolarization.
Action of Insulin on Vascular and Intestinal Smooth Muscle. Effects on Amino Acid Transport, Protein Synthesis and Accumulation of Glucose Carbon
Authors: Arnqvist Hans J. 
Published: December 2008

AbstractThe effects of insulin (0.1 U/ml) on the glucose metabolism in vascular and intestinal smooth muscle are weak in comparison with those in skeletal muscle and also appear later (Arnqvist 1973). In this study insulin (0.1 U/ml) was found to stimulate the membrane transport of α‐aminoisobutyric acid‐14C (AIB‐14C) and the incorporation of leucine‐14C into protein in bovine mesenteric arteries and rabbit colon smooth muscle. Also these effects were weaker and appeared later than the corresponding effects in skeletal muscle. The dose‐response curves for the accumulation of glucose‐14C and the incorporation of leucine‐14C into protein in bovine mesenteric arteries were both displaced to the right in comparison with those for rat diaphragm. Blocking protein synthesis by puromycin did not abolish the effect of insulin on the accumulation of glucose‐14C. The sensitivity of bovine mesenteric arteries to the effect of insulin on the accumulation of glucose‐14C did not increase during the incubation period. The finding that all the diverse effects of insulin on smooth muscle were weaker and appeared later than those in skeletal muscle may indicate that they are initiated by a common receptor mechanism which differs in smooth muscle and skeletal muscle.
Group I Inhibition in Ib Excited Ventral Spinocerebellar Tract Neurones
Authors: Lindström S. , Schomburg E. D. 
Published: December 2008

AbstractThe convergence of inhibition and excitation from muscle spindle Ia and Golgi tendon organ Ib afferents was investigated in ventral spinocerebellar tract (VSCT) neurones monosynaptically excited from Ib afferents. Although most cells received Ib excitation from several nerves, the dominating excitation was supplied from nerves to synergistic muscles acting as either flexors or extensors at one joint. Disynaptic Ia lPSPs from the nemc to the knee extensor were common in cells with their main Ib excitation from the nerves to either hip, knee or ankle extensors or to knee flexors. The Ia IPSPs in cells excited from hip extensors and knee flexors were depressed by antidromic impulses in motor axons, while no such effect occurred on Ia IPSPs in the other cells. The Ia IPSPs in Ib VSCT neurones thus seem to be mediated by two different groups of Ia inhibitory interneurones, with and without recurrent inhibition from motor axon collaterals through Renshaw cells. Disynaptic Ib IPSPs from nerves to thigh muscles were rare while presumed Ib IPSPs from nerves to ankle and toe muscles were more common. In some cells there were indications of convergence of monosynaptic EPSPs and disynaptic IPSPs from Ib afferents in the same nerve. The results are discussed in relation to the hypothesis that the VSCT relays information about interneuronal transmission in the spinal cord.
Recovery Time in the Visual Cortex of Guinea Pigs and of Ground Squirrels
Authors: Hammerberg Poul E. 
Published: December 2008

AbstractThe cortical irresponsive and recovery times were tested in albino guinea pigs and in ground squirrels with the same brief (1 ms) colored flashes and using the same anesthesia, dial. The irresponsive time was much longer, 60–80 ms, in the guinea pig compared with 15–20 ms in the squirrel. In the squirrel the retinal was at least 5 ms shorter than the cortical recovery time, and the retinal response reached 50 % of full amplitude when 25 ms separated the flashes compared with 100 ms for the cortical response. Since the conditioning and testing flashes had the same intensity, the irresponsive time diminished with decreasing strength of light until close to threshold in the guinea pig. The threshold was high in squirrel and flashes of maximum intensity were used with color filters. There was no difference between responses to colored flashes when the amplitude of the responses was the same, either in guinea pig or squirrel. In the guinea pig chloralose‐urethane anesthesia resulted in a longer irresponsive time, and with some light intensities there was a period when the response to the testing flash was larger than to the first flash, as has been described in cat.
Uptake of Histamine or Histamine Metabolites into Sympathetic Nonadrenergic Axons
Authors: Ehinger B. 
Published: December 2008

AbstractRabbit tissues were exposed to tritiated histamine or histidine either by intraocular injections (iris) or by incubations (iris, superior cervical ganglion). When the iris was exposed to tritiated histamine, radioactivity appeared in a pattern very similar, but not completely congruent, to that of the adrenergic terminals. The neuronal radioactivity disappeared after sympathetic denervation and also after decentralization of the superior cervical ganglion. Application of tritiated histidine did not give rise to any neuronal radioactivity. Sympathetic ganglion cells did not accumulate histamine under conditions when nerve fibres did. The experiments suggest the possibility of a set of sympathetic nonadrenergic axons accumulating histamine or histamine metabolites. If so, these axons run close to the adrenergic terminals, and presumably they arise in structures situated centrally of the superior cervical ganglion. It is further concluded that there is under normal conditions no very efficient neuronal conversion of histidine to histamine in the uvea.
Pulmonary Vascular Effects of Suddenly Induced Unilateral Blood Platelet Aggregation
Authors: Bø G. , Hognestad J. 
Published: December 2008

AbstractEmbolization of one or both lungs was achieved in cats by intravascular infusions of a collagen suspension. On intravenous collagen infusion, with platelet aggregates reaching the vasculature of both lungs, large pulmonary pressor responses were obtained. Unilateral platelet aggregation in blood to the lungs was achieved by infusion of collagen into the right pulmonary artery. The resulting pressure/flow response indicated that blood flow was diverted to the contra‐lateral lung. There was no indication that the pulmonary vascular resistance was increased in this contralateral. non‐embolized lung. It appears therefore that only vasculature in the lung which received platelet emboli is involved in the vasoconstriction following unilateral embolization of this type.
Lowered Chronotropic Sensitivity of Rat and Frog Hearts to Sympathomimetic Amines Following Cold Acclimation
Authors: Tirri R. , Harri M. N. E. , Laitinen Leena 
Published: December 2008

AbstractCold acclimation elevated the basic heart rate in the rat and decreased the chronotropic sensitivity to noradrenaline and isoprenaline. These changes reached their maximum after a week but returned to the initial level after a month of prolonged cold acclimation. Phenylephrine failed to increase the heart rate under thein uiuoconditions used. In the frog, cold acclimation lowered the heart chronotropic sensitivity most significantly to phenylephrine, less to adrenaline and not at all to isoprenaline, as indicated by changes in the EDSO‐values. This lowered sensitivity to adrenaline reached its maximum level after 2–4 days of cold exposure and had not returned to normal after 20 days. In both cold‐ and warm‐acclimated frogs the elevation of the temperature, where the heart rate was measured, decreased the sensitivity to phenylephrine.
Afferent Discharge from Human Muscle Spindles in Non‐Contracting Muscles. Steady State Impulse Frequency as a Function of Joint Angle
Authors: Vallbo A. B. 
Published: December 2008

AbstractImpulses in single muscle spindle afferents from the antebrachial finger flexor muscles were recorded from the median nerve of waking human subjects. The discharge frequency in the steady state was measured as the metacarpo‐phalangeal joint angles were passively changed in steps. At a comfortable resting position of the hand, less than ten percent of the spindle primaries were discharging. Within intermediate ranges of muscle lengths the discharge frequency of the single units did not exceed 20 impulse per second (ips). The response to joint movements was that expected from muscle stretch and muscle release alone and there was no indication of fusimotor adjustments as a result of joint movement. The frequency of the single units increased linearly with joint extension, the mean sensitivity of the primaries being 0.18 ips per degree which is about 5 times lower than the sensitivity of de‐efferented spindles in cat ankle extensors. The afferent discharge from the secondaries was in most respects very similar to that of the primaries. The low discharge frequency, the low percentage of active units and the low position sensitivity all indicate an insignificant fusimotor outflow to relaxed human hand muscles and a comparatively poor ability of the spindles to measure muscle length under these conditions.
Effects on Cerebral Energy State of Arterial Hypotension in Rats with Porta‐Caval Anastomosis
Authors: Holmin Torsten , Jóhannsson Halldór , Siesjö Bo K. 
Published: December 2008

AbstractThe influence of arterial hypotension upon the energy state of thc brain was studied in rats with porta‐caval anastomosis by bleeding the animals to mean arterial blood pressures of 45 and 30 mm Hg, respectively. Reduction of blood pressure to 45 mm Hg in shunted rats gave no or only very moderate accumulation of lactate and there were no changes in the contents of ATP, ADP and AMP in frontal lobe or brainstem. At a mean blood pressure of 30 mm Hg shunted animals and controls showed similar values for glycolytic and citric acid cycle intermediates, amino acids and adenine nucleotides in frontal lobe, parietal cortex and Drainstem. It is concluded that the shunting procedure, and the ensuing hyperammonemia, does not adversely affect the sensitivity of the cerebral energy state to arterial hypotension.
Respiratory and Cardiovascular Responses to Electrical Stimulation of the Avian Brain with Emphasis on Inhibitory Mechanisms
Authors: Kotilainen P. V. , Putkonen P. T. S. 
Published: December 2008

AbstractRespiratory and circulatory responses to electrical brain stimulation were studied in 30 anesthetized chicken from about 850 histologically verified loci in an attempt 1) to delineate the limits and characterize the response patterns of a thalaniic cardioinhibitory area (Putkonen 1967) and 2) to extend exploration of respiratory and circulatory functions of the avian brain to telecephalic and mesencephalic levels. Apnea or partial respiratory inhibition were obtained from; 1) an anterolateral thalamic field in front and around the nurotundus, 2) the entire course of the quinto‐frontal tract, which was the only forebrain site yielding apnea and from 3) a medial and a lateral mesencephalic area. The apnea from the antero‐lateral thalamus was associated with progressive bradycardia and fall in blood pressure which both could be almost abolished during tracheal infusion of oxygen. Apneic bradycardia from the mesencephalic quinto‐frontal tract was associated with hypertension thus mimicking the “diving reflex”. Varying patterns of respiratory and circulatory activation, often with vocalizations, were obtained from; 1) septal and preoptic areas, 2) medial archistriatal regions, 3) the occipito‐mesencephalic tract and from 4) a large field in the mesencephalic lateral reticular formation. The results are discussed in relation to pertinent literature from birds and mammals with an emphasis on inhibitory mechanisms.
Labelled 5‐Hydroxytryptamine and 5‐Hydroxyindoleacetic Acid Formed in Vivo from ‘H‐Tryptophan in Rat Brain; Effect of Probenecid*)
Authors: Schubert Johan 
Published: December 2008

AbstractProcedures were developed for determination of labelled 5‐hydroxytryptamine (5‐HT) and 5‐hydroxyindoleacetic acid (5‐HIAA) formedin viuofrom3H‐tryptophan in rat brain. Tryptophan, 5‐HT and 5‐HIA.4 in brain extracts were isolated on columns of Dowex 50W‐X4, Amberlite CG 50, and Sephadex G 10, recoveries being 64 %, 78 % and 66 % respectively. Following i.v. injection of3H‐tryptophan labelled 5‐HT and 5‐HIAA accumulated in brain, reaching maximal levels after approximately 15 and 60 min respectively. The relationship between the specific activity curves for 5‐HT and 5‐HIAA appeared to be consistent with single compartment kinetics for 5‐HT. The effect of probenecid (200 mg/kg) on the amounts of labelled 5‐HT and 5‐HIAA formed from3H‐tryptophan indicates that besides inhibiting 5‐HIAA efflux from brain the drug also enhances 5‐HT synthesis.
Intracortical Distribution of Renal Blood Flow during Saline Infusion in Dogs
Authors: Løyning E. W. 
Published: December 2008

AbstractThe increase in sodium excretion induced by isotonic saline infusion has been attributed to a redistribution of blood flow within the cortex to “salt‐loosing” superficial nephrons. To test this hypothesis, mean blood flow to outer (OCF) and inner (ICF) cortex was measured in dogs before and during saline expansion, using H2‐clearance rates as indicator of local blood flow. Mean total blood flow (RBF) was measured with an electromagnetic flowmeter. During infusion of 0.9 % NaCI, 30 ml/min for 30–80 min, urine flow increased from 1.1 to 7.5 ml/min, glomerular filtration rate from 39.8 to 49.1 ml/min, RBF rose from 214 to 276 ml/min, OCF from 3.43 to 3.87 ml/min and ICF from 3.50 to 3.91 ml/min. OCF/ICF did not change significantly during saline expansion. Autoregulation of local blood flow was maintained after saline loading with no change in OCF/ICF within the pressure range of autoregulation. Since massive saline infusion is followed by a parallel increase in blood flow to outer and inner cortex, it is concluded that intracortical redistribution of blood flow is not the mechanism of natriuresis during saline loading.
Renal Lithium Clearance during Dehydration and Rehydration with Water or 0.9% NaCl in the Rat
Authors: Smith Donald F. 
Published: December 2008

AbstractMale albino rats fed a diet containing lithium were dehydrated by 24 h of water deprivation and then rehydrated with demineralized water or 0.9 % NaCl. Renal lithium clearance decreased during rehydration with water. Rehydration with 0.9 % NaCl prevented the fall in the rate of urinary lithium elimination. The decrease in renal lithium clearance in the rats rehydrated with water was due to an increased fractional reabsorption of lithium in the renal tubules and was associated with a decrease in renal sodium clearance. The relationship between the renal elimination of sodium, potassium, and lithium during rehydration is discussed.
Actions of Intravenous Ca++ and Na+ on Body Temperature in Rabbits
Authors: Nielsen Bodil 
Published: December 2008

AbstractRectal temperatures in rabbits were found to increase when hyperosmotic NaCl solution were infused in the marginal earvein, while infusion of CaCl2 caused a fall in rectal temperature. The latter effect was much more pronounced in cold (14° Ta) environment. It could be shown that the ions affected the peripheral circulation and therefore the heat loss. It is concluded that the observed changes in body temperature most likely are secondary to the peripheral changes in heat loss, and not a thermoregulatory change in the set‐point of the hypothalamic centres.
Contraction in Venous Smooth Muscle Induced by Hypertonicity. Calcium Dependence and Mechanical Characteristics
Authors: Andersson Christer , Hellstrand Per , Johansson Börje , Ringberg Anita 
Published: December 2008

AbstractA tonic increase in tension was observed in the isolated rat portal vein in response to large increases in extracellular tonicity (1.5–3 times normal). The purpose of this study was to find out whether this tension increase was due to active contraction or passive shrinkage. The metabolic dependence of the response and its mechanical characteristics, as revealed by quick release experiments, lead to the conclusion that active contraction is the predominant mechanism. The maximal force developed in the hypertonicity contracture amounted to 31 per cent of the maximal K+ contracture obtained in isotonic medium. The hypertonicity contracture occurred independent of the level of membrane potential and in the absence of external Ca2+ (below 10‐‐9 M). It is thus elicited through mechanisms which differ in these respects from the electromechanical cbupling operating in the K+ contracture. The speed of shortening against a given afterload was found to be lower in a hypertonicity contracture than in a K' contracture of comparable isometric force. Explanations for observed differences between the two types of contracture are discussed.
Renal Control of Salt and Fluid Homeostasis during i. v. Saline Infusion
Authors: Aperia Anita , Broberger Ove 
Published: December 2008

AbstractThe renal effect of infusion of hypo‐, iso‐ and hypertonic saline has been studied in dogs. The infusion rate was comparatively low, 1 % of the b.wt./45 min. The kidneys responded almost instantaneously to the infusion with diuresis and natriuresis. The response was due primarily to an adaptive inhibition of tubular reabsorption. Increases in filtered load of Na+ occurred only as a function of increased serum Na+ concentration, i.e. only when the hypertonic saline solution were used. The inhibition of tubular reabsorption was mainly signalled by the fall in serum protein concentration. Changes in Na+ balance and serum Na+ concentration did not contribute to the adaptive inhibition of tubular reabsorption. The effect of the diuretic and natriuretic response on fluid and Na+ balance depended primarily on the tonicity of the infused fluid. When the 75 and 150 mEq solutions were used, fluid balance became positive, but did not increase much when more than 2 % of the b.wt. had been given. When the hypertonic saline solutions were used total fluid balance became increasingly negative. The Na+ balance was best controlled with the hypotonic saline solution. Vhen hypertonic saline waq given Na+ balance increased almost at the same rate as Na+ was given.