bluuebunny/crossref_metadata_2025_split huggingface dataset:
Uptake and Release of u‐Methyl‐Noradrenaline in Vitro after Reserpine Pretreatment A Histochemical Study
Authors: Hamberger Bertil , Malmfors Torbjörn 
Published: December 2008

AbstractThe reserpine‐rcsistent uptake and storage of α‐methyl‐noradrenaline in vitro were investigated in thr adrenergic nerves of the rat iris. After reserpine pretreatment, an effective accumulation of α‐methyl‐noradrenaline took place intraneuronally. The amine remained intraneuronally for several hours ivhen incubated in amine‐free medium at 37°C. The morphological appearancc changed during the incubation in a manner suggesting that part of the amine was bound to an intraneuronal structure, which might be the amine storage granules. Interference with energy generation in the ˜ncdiurn, as well as chemical depolarization by increasing potassium ion concentration in the inediuin, inhibited accumulation and caused a rapid release of α‐methyl‐noradrenaline. Protriptyline inhibited the uptake of α‐methyl‐noradrenaline efficiently, and also enhanced the disappearance of accumulated amine. Although (+)‐amphetamine was less potent in preventing uptake. it produced a rapid rclease of the amine.
The Role of Gastric Mucosal Mast Cells during Triton WR‐1349 Lipemia of Rats
Authors: Haikonen Matti , Räsänen Toimi , Taskinen Eero 
Published: December 2008

AbstractRats were intraperitoneally injected with 1 × 50 mg and 3 × 50 mg of Triton WR‐1339. There occurred steep increase in esterified fatty acids and cholesterol, and the plasma proteins decreased. The mucosal mast cell count and the metachromatic granulation of these cells increased, after a primary decline, in the gastric and jejunal walls under the effect of Triton. The bearing of the phenomenon on hyperlipaemia is considered in the discussion, bringing up the potential inhibition of heparin release.
The Effects of Hypercapnia and Hypoxia on the Distribution of Capillary Blood Flow in the Denervated Intestinal Vascular Bed
Authors: Svanvik Joar , Tyllström Jöran , Wallentin Ingemar 
Published: December 2008

AbstractExperiments are described which demonstrate that both hypercapnia and hypoxia exert a potent relaxing influence on the resistance vessels of the denervated intestine. The effects on the capillary fluid exchange capacity, as indicated by the capillary filtration coefficient (CFC), are, however, more complex. During local hypoxia CFC increases considerably, probably reflecting a direct relaxing influence on the precapillary sphincter section. In contrast, during hypercapnia CFC decreases in spite of an augmented blood flow. This is assumed mainly to be due to an increased myogenic activity in the same sphincter section, elicited locally by a raised transmural pressure and blood flow. Functional implications of the results are briefly discussed. They suggest that neither high Pco2 accompanied by a low pH, nor low Po2 are of major importance for a functional intestinal hyperemia during digestion.
The Effect of Some Neutral Macromolecules on the Pattern of Hypotonic Hemolysis
Authors: Davies Howard G. , Marsden N. V. B. , ÖStling S. Göran , Zade‐Oppen A. M. M. 
Published: December 2008

AbstractThree neutral polymers, ficoll, dextran and polyethyleneglycol, all inhibit hemoglobin liberation in hypotonic electrolyte solutions. If red cells are suspended in a hypotonic solution which, in the absence of a polymer, would hemolyse all the cells, only a part of the hemoglobin is liberated. The polymer does not alter the fragility but only the amount of hemoglobin liberated from the individual cells. The inhibitory effect is proportional to the weight concentration of the polymer and independent of the mol. wt. within wide limits. The inhibitor molecules must presumably have a critical minimal size since the trisaccharide raffinose did not inhibit hemoglobin liberation under similar conditions. From the data on the lowest molecular weight dextran fraction it was concluded that the lower limit for dextran was below a molecular weight of about 1700. Complete inhibition of hemoglobin liberation was never obtained and from the evidence available it is suggested that the first 20 per cent, at least, of the hemoglobin may escape with a bulk outflow. The colloid osmotic relationships of the cell during and after hemolysis are discussed and it is concluded that cannot be decided whether the polymer effect is colloid osmotic in nature.
Intracellular Distribution of Lipolytic Enzymes in the Rat Pancreas
Authors: Arnesjö Bo , Filipek‐Wender Helena 
Published: December 2008

AbstractIntracellular distribution of lipase (glycerolester hydrolase EC 3.1.1.3.), cholesterol esterase (sterol ester hydrolase EC 3.1.1.13.), phospholipase (EC 3.1.1.4.) and of carboxylic ester hydro‐lases (EC 3.1.1.1.) has been studied using isopycnic gradient centrifugation of rat pancreatic homogenates. The identity of the fractions obtained has been established using phase contrast and electron microscopy. Zymogen granules equilibrated at a mean density of 1.224 in aqueous sucrose gradients, mitochondria and cytomembranes at a mean density of 1.19 and 1.16–1.14, respectively. The zymogen fraction accounted for 25–45 % of the total activities of lipase, cholesterol esterase and phospholiphase. The specific activities (activity per mg protein) in the zymogen fraction were 5–7 times higher than those of the other cell fractions. A bile salt stimulated carboxylic ester hydrolase was found concentrated to the zymogen granules. The membrane and cell sap fractions accounted for almost all of the remaining lipolytic enzyme activities.
Changes in Dynamic Sensitivity of Primary Endings of Muscle Spindle Afferents Induced by DOPA
Authors: Bergmans J. , Grillner S. 
Published: December 2008

AbstractIn the spinal unanesthetized cat, muscle spindle afferents from primary endings originating in the tenuissimus muscle were studied during a ramp stretch to the muscle with intact efferent nerve supply before and after an intravenous injection of DOPA. It was demonstrated that the peak and mean frequency during stretch was decreased after DOPA, when there also occurred firing during release of stretch. The results indicate that there is after DOPA a decreased spontaneous activity in dynamic y‐motoneurones and a concomitant increase in static fusi‐motor activity. The findings support the idea that descending noradrenergic fibres control, in a reciprocal fashion, the spontaneous activity in static and dynamic y‐motoneurones to flexors.
Role of Uptake and Oxidation of Plasma Free Fatty Acids by the Liver in the Development of the Ethanol‐Induced Fatty Liver
Authors: Fex Göran , Olivecrona Thomas 
Published: December 2008

AbstractGroups of fasted female rats were tube fed ethanol (6 g/kg b.w.), an isocaloric amount of glucose, or nothing. Half of the rats in each group were given hourly s.c. injections of nicotinic acid. 6 hrs after the feeding, 9–10‐H3 oleic acid complexed to serum albumin was injected intravenously. 5 min later the rats were killed and concentrations of plasma free fatty acids and of liver glycerides and labeling of liver and carcass lipids was determined.Plasma free fatty acid concentrations were similar in the ethanol fed and the fasted rats but lower in the glucose fed rats. In all groups nicotinic acid lowered plasma free fatty acid concentration.Liver glyceride concentration was elevated in the ethanol fed rats. In all groups nicotinic acid lowered the liver glyceride concentration.Total liver radioactivity was highest in the ethanol fed rats, intermediary in the glucose fed rats and lowest in the fasted rats. The liver radioactivity was not significantly changed by nicotinic acid. It is suggested that the differences in liver radioactivity between the groups reflects differences in the oxidation of plasma free fatty acids taken up by the liver and that a major cause of the ethanol induced fatty liver is a decreased hepatic oxidation of plasma free fatty acids taken up at a normal rate.
Possible Functional Differentiation between the Stores from which Adrenergic Nerve Stimulation, Tyramine and Amphetamine Release Noradrenaline
Authors: Obianwu Hopé O. 
Published: December 2008

AbstractEffects of inhibition of monoamine oxidase and tyrosine hydroxylase on the contraction of rat lower eyelid and pressor response to tyramine, amphetamine and adrenergic nerve stimulation have been studied. Inhibition of MAO markedly enhanced both the peak and the duration of response of the eyelid to tyramine and amphetamine while only moderately augmenting the durations of pressor response to tyramine. Contraction of the eyelid to nerve stimulation was not affected.Inhibition of tyrosine hydroxylase abolished the contraction of the eyelid to amphetamine while only slightly reducing that to tyramine. The contraction of the eyelid to nerve stimulation was not affected.The results suggest that nerve stimulation, tyramine and amphetamine release noradrenaline from different stores. The nature of these stores is discussed.
Intracellular Distribution of Lipase in Comparison to Trypsinogen, Amylase and Immediately Measureable Trypsin Inhibitor(s) in the Rat Pancreas
Authors: Arnesjö Bo , Grubb Anders 
Published: December 2008

AbstractThe intracellular distribution of lipase (glycerol ester hydrolase EC 3.1.1.3.), trypsinogen (EC 3.4.4.4.), amylase (EC 3.2.1.1.) and immediately measurable trypsin inhibitor(s) has been studied using isopycnic gradient centrifugation of rat pancreatic homogenates. A modified method for the measurement of trypsinogen is presented and a micromethod for the estimation of trypsin inhibitory activity is described. By comparison with lipase smaller proportions of the total trypsinogen and amylase activities were recovered from the zymogen fractions. The total immediately measurable trypsin inhibitory activity was mainly localised in the cytomembrane fractions, while virtually no activity was found in the zymogen granules. The specific activity (activity per mg protein) for both amylase and trypsinogen was high in the zymogen and in the cell sap fractions. For lipase and immediately measurable trypsin inhibitory activity, however, the specific activity was high only in the zymogen granules and cytomembranes, respectively.
Ventilation Hypoxia and Pulmonary Vascular Resistance Effects of Changes in Plasma Potassium Concentration
Authors: Hauge Anton 
Published: December 2008

AbstractThe effects of stepwise rises in plasma potassium concentration on the pressor responses to short (less than 3 min) periods of ventilation hypoxia and to vasoconstrictor agents, were investigated in isolated blood‐perfused rat lungs. Both hypoxia‐responses and drug‐responses were potentiated. Plasma potassium ion concentrations above 17.0 to 18.8 meq/l caused dose‐dependent sustained elevations of pulmonary vascular resistance (PVR). Ventilation hypoxia superimposed on such high PVR did still cause brisk pressor responses. Potassium‐induced vasoconstriction were obtained also in periods with no pressor responses to ventilation hypoxia i.e. by cooling of the perfusate or late in a perfusion. The results suggest that a reduction of the vascular smooth muscle cell ratio [K+]i/[K+]0 by hypoxia‐induced transcellular leakage of potassium‐ions is not the sole mechanism for the pressor response to acute ventilation hypoxia.
Effects of Increased Intracranial Pressure on Cerebral Blood Flow and on Cerebral Venous pO2, pCO2, pH, Lactate and Pyruvate in Dogs
Authors: Kjällquist Å. , Siesjö B. K. , Zwetnow N. 
Published: December 2008

AbstractThe effects of increased cerebrospinal fluid (CSF) pressure on cerebral blood flow and on cerebral venous pO2, pCO2, pH, lactate, and pyruvate were studied in dogs by infusing an artificial CSF into the cisterna magna. With moderate and rapid increases in the CSF pressure, which did not lower cerebral perfusion pressure below 60–70 mm Hg, the cerebral blood flow was not measurably lowered, although there were sometimes detectable metabolic changes in cerebral venous blood suggestive of a transient reduction of the cerebral blood flow. That is, cerebral venous pO2 and pH decreased slightly, and there were increases in the cerebral venous pCO2, in the lactate and pyruvate concentrations, and in the lactate/ pyruvate ratios, indicating an anaerobic glucolysis. When the pressure was released there was usually no reactive hyperemia, and no persisting metabolic changes in the cerebral venous blood. When the CSF pressure was markedly increased, and the cerebral perfusion pressure accordingly reduced to 30–50 mm Hg there were marked metabolic changes in cerebral venous blood, the pO2 often approaching 10 mm Hg. In this case, a sudden reduction of the CSF pressure was almost invariably followed by a significant reactive hyperemia, which was paralleled by an arterialization of cerebral venous blood with a high pO2 and a low pCO2. The changes in pO2 usually expressed the changes in flow. During and after the reactive hyperemia there were no lactate/pyruvate changes to indicate the preceding period of anaerobic glucolysis.
Studies of Blood‐pressure Regulation
Authors: ÖBerg P. Å. , Sjöstrand U. 
Published: December 2008

AbstractA method has been worked out by which one of the closed control circuits in the blood‐pressure‐regulating system of the dog can be reversibly opened and closed again with the aid of an on‐line analog computer. This makes it possible to study the regulatory properties of the carotid‐sinus reflex, as regards the baroreceptor function, in the regulation of the systemic blood pressure. Proportional characteristics in the analog produce marked instability in the blood‐pressure regulation, while with increasing proportional‐plus‐derivative characteristics the stability is increased. The electronic analog can be given characteristics that produce the same step‐function response in the systemic pressure as the biological reflex.
The Influence of Arterial PO2 on Renal Tissue PO2
Authors: Aperia Anita C. 
Published: December 2008

AbstractWhen arterial PO2 is increased to supra‐atmospheric tensions approximating 500 mm Hg in the dog, the PO2 of the renal cortex rises from under 50 mm Hg to the range of 130 mm Hg, in contrast with that of the outer medulla which may even fall; there is little absolute change in the already extremely low PO2 of the inner medulla. These observations are interpreted to support the idea of a homeostatic mechanism operating to regulate medullary blood flow as already suggested by observations of urine PO2 at various arterial O2 tensions. This mechanism helps to maintain the hypoxic state of the medulla appropriate to its relatively anaeroboic metabolism.
Neurogenic Adjustments of Muscle Blood Flow, Cutaneous A‐V Shunt Flow and of Venous Tone during “Diving” in Ducks
Authors: Djojosugito A. M. , Folkow B. , Yonce L. R. 
Published: December 2008

AbstractThe effect of “diving” on the vascular response in skeletal muscle, the web and the veins was studied in experiments on ducks. Muscle blood flow completely stopped during submersion due to neurogenic vasoconstriction of the resistance vessels, at the same time as the constrictor fibres to the systemic veins were excited. As a contrast, web blood flow changed only little during submersion, unless the duck was excited. In this latter case it decreased, whether the animal was submerged or not. The profound muscle vasoconstriction helps to conserve the oxygen stores for the “essential” tissues, the heart and the brain. The preserved web blood flow, on the other hand, primarily passes through A‐V shunts and, in conjunction with the venous constriction, it pushes blood from the considerable, oxygen‐containing venous depots to the heart without causing peripheral oxygen “losses” from the blood. Such mechanisms serve to make the total venous oxygen stores available for subsequent cardiac output to the brain and the myocardium.
Adrenergic Neuron Blockers and Transmitter Release after Sympathetic Denervation Studied in the Conscious Rat
Authors: Lundberg Dag 
Published: December 2008

Abstract13 to 15 hrs after excision of the superior cervical ganglion the postdenervation ptosis in the rat is reversed for about 12 hrs due to release of transmitter from degenerating nerve terminals. This degeneration contraction has been studied in unanesthetized rats. A special apparatus with an image splitting eyepiece was constructed for the measurement of the palpebral aperture at a distance. The time course of the degeneration contraction was found to correlate well with that of postdenervation transmitter depletion earlier found by other workers using biochemical and histochemical methods. Earlier findings that postdenervation depletion is delayed by bretylium were fully confirmed. It was also found that the neuron‐blockers beta‐TM 10 (10–50 mg/kg), bethanidine (10–50 mg/kg) and BW 392C60 (10–75 mg/kg) caused much less delay than bretylium at 1 to 50 mg/kg. The delayed degeneration contraction has a normal appearance and magnitude. There is no correlation between the neurone blocking action of the drugs and their “delaying effect”.
Electrical Stimulation of a Human Ventrolateral‐Subventrolateral Thalamic Target Area
Authors: Johansson Gunnar G. 
Published: December 2008

AbstractA ventrolateral‐subventrolateral thalamic target area was electrically stimulated in connection with stereotaxic neurosurgery in 20 alert patients with Parkinson's disease, in 5 patients with hereditary intention tremor and in 1 patient with an atypical congenital tremor. The purpose of the investigation was to study whether an altered pulse duration had any effect on the projected clinical responses evoked by the stimulation. Unidirectional square wave pulses with durations ranging from 0.1 to 25 msec and a repetition frequency of 1 pulse per second were therefore applied. The stimulation threshold for clinical responses was maintained by balancing every pulse duration tested with the peak current. The responses consisted mainly of muscular jerks or twitches projected to various contralateral parts of the body. The localization of the threshold responses depended on the pulse duration used. The motor character of the responses remained unchanged with all pulse durations tested. The peak current‐pulse duration relationship for the threshold responses was studied. The results are discussed.
A Cyclic Variation in the Exfoliation of Cells from the Urethra of the Male Mouse
Authors: Jäurnebrand K. , Kihlströum J. E. 
Published: December 2008

AbstractFive different types of exfoliated cells, representing different stages of cornification, have been observed in daily urethral smears from male mice. The frequencies of the cells belonging to two of these types vary cyclically. The mean duration of the cycles is about 3.5 days.
Role of Autoregulation in Maintaining Glomerular Filtration Rate at Large Urine Flow
Authors: Kiil F. , Kjekshus J. , Löyning E. 
Published: December 2008

AbstractThe effects of large urine flow and high tubular pressure on renal blood flow (RBF) and glomerular filtration rate (GFR) were studied in dogs. In unanesthetized animals, ethacrynic acid and furosemide infused during hypotonic saline or mannitol diuresis increased urine flow to more than half of the filtered load without reducing GFR, whereas clearance of paraamino‐hippurate (CI’.VH) rose. In anesthetized dogs, ethacrynic acid and furosemide increased RBF. By stepwise renal artery constriction RBF was reduced in proportion to perfusion pressure, indicating abolished autoregulation. A similar moderate increase in RBF and abolition of autoregulation were also obtained by ureteral obstruction. In contrast, autoregulation was maintained until RBF was nearly doubled during infusion of saline or mannitol. During infusions of hypotonic solutions, CPAH increased despite reductions in serum osmolality which in renal perfusion experiments led to a fall in RBF.Conclusion: High tubular or intestitial pressure acts on the autoregulating mechanism which dilates afferent arterioles until the hydrostatic pressure difference over the glomerular membrane is reestablished. By this mechanism, RBF is increased and GFR maintained at high urine flow. Vasodilating factors may be elicited during expansion of extracellular volume, but do not affect autoregulation and are without distinct effect on GFR.
A Comparative Study of K42 and Na24 Movements during the Cardiac Cycle
Authors: Coraboeuf E. , Delahayes J. , Sjöstrand U. 
Published: December 2008

AbstractStudies of K42 and Na24 movements during the cardiac cycle were made on right ventricle from the rat and guinea‐pig, on frog atrium and on frog ventricular strips. The methods used in these studies have been described in earlier papers cited in the text. The K42 study showed a cyclic leakage of radioactive potassium from the rat ventricle: no such leakage was observed in ventricle from the guinea‐pig. Both frog preparations showed an increase of K42 efflux during the electrical activity. The Na24 study showed a slight decrease in the radioactive sodium efflux from the rat and guinea‐pig ventricle at the depolarization phase and the first part of the action potential; in frog preparations a large increase in the activity efflux preceded by a slight decrease was observed. The possibility of mechanical artifacts is discussed and an interpretation of the results is proposed which is based on a different pattern of potassium permeability between the species, the guinea‐pig and frog showing a “rectangular” action potential and the rat a “sigmoid” action potential. The slight decrease in Na24 activity preceding the mechanical systole could reflect the basic ionic mechanisms of the depolarization.
Embryological Observations of the Ductus Arteriosus in the Guinea‐Pig, Rabbit, Rat and Mouse. Studies on Closure of the Ductus Arteriosus. IV
Authors: Hornblad P. Yngve 
Published: December 2008

AbstractFetuses of guinea‐pigs, rabbits, rats and mice were obtained by caesarean section in late pregnancy. They were immediately sacrificed, and fixed by whole‐body freezing, after which transverse cryostat sections of the ductus arteriosus were prepared for morphological observations. The inner diameter and wall thickness of the ductus were measured at its narrowest part. The descending thoracic aorta of full‐term rat fetuses was treated in the same way as the ductus.In all species, the mean inner diameter of the ductus increased with fetal age, and was accompanied in the guinea‐pig and rabbit by a gain in thickness of the media. The development of an intima was most evident in rabbit fetuses. In all species, the structure of the ductal wall was comparable in the youngest and oldest fetuses.The inner diameter and wall thickness of rat and mouse fetuses near term corresponded well to values in newborns. The divergent values between fetuses and newborns of the guinea‐pig and rabbit are discussed. The relation recorded between the cross‐sectional areas of the ductus arteriosus and thoracic aorta is in agreement with the present concepts of prenatal circulation.The similarities in ductal morphology between full‐term fetuses and newborns might justify the use of full‐term fetuses in experiments on the physiology of the ductus arteriosus.