bluuebunny/crossref_metadata_2025_split huggingface dataset:
Renal Autoregulation during Infusion of Noradrenaline, Angiotensin and Acetylcholine
Authors: Kiil F. , Kjekshus J. , Löyning E. 
Published: December 2008

AbstractTo examine whether renal autoregulation was abolished by vasoconstriction and vasodilatation, experiments were performed on anesthetized dogs with intact renal circulation and nervous supply. Angiotensin or noradrenaline was infused into the renal artery at a constant rate that reduced renal blood flow (RBF) to less than half of control values. By mechanical constriction of the renal artery, perfusion pressure could be reduced to averages of 69 and 80 mm Hg respectively (74 mm Hg during control conditions), before RBF dropped more than 5%. Normal autoregulation was also obtained during intravenous infusion of angiotensin and noradrenaline. during stimulation of renal nerves, and after development of tachyphylaxis to angiotensin. At normal and low arterial pressures, but at similar RBF, noradrenaline or angiotensin was injected into the renal artery. RBF was least reduced at low perfusion pressure, indicating that autoregulation did not compensate for the vasoconstrictive effect of noradrenaline and angiotensin. By acetylcholine infusion. RBF could be doubled, and a curvilinear relationship between RBF and perfusion pressure was obtained. Similar curves could be constructed by the application of Poiseuille's law on the premise that vasoactive agents act mainly on muscle elements other than those participating in autoregulation. It is concluded that autoregulation is essentially independent of nervous and humoral stimuli.
Effect of Oxygen and Umbilical Cord Clamping on Closure of the Ductus Arteriosus in the Guinea‐Pig and the Rat. Studies on Closure of the Ductus Arteriosus. VI
Authors: Hörnblad P. Yngve 
Published: December 2008

AbstractFull‐term guinea‐pigs were delivered by caesarean section. Living fetuses with intact, or interrupted umbilical circulation were allowed to breathe, for periods of 5 min, air or nitrogen, or air followed by nitrogen. Animals sacrificed immediately on birth served as controls. Sacrifice was performed in liquid nitrogen.–Spontaneously delivered rats were either sacrificed immediately on birth or kept up to 4 hrs at 37° C in air or 8 c/c O2 in N2, before sacrifice in isopentane. cooled by dry ice. In addition, the heart rate of newborn rats, kept at the same temperature and in the same atmospheres, was recorded. – Changes in ductal inner diameter and wall thickness were measured in cryostat sections of both species. Oxygen caused marked constriction of the ductus in the guinea‐pig. Further constriction was found in animals with a clamped umbilical cord. No evidence was obtained of an effect of nitrogen inhalation, neither on the open nor on the constricted ductus. In the rat, reduced atmospheric oxygen concentration caused a delay in ductal closure rate. Lowering of the heart rate was also observed. The present results–obtained in vivo in the guinea‐pig and rat–show that oxygen is essential for closure of the ductus arteriosus, independent of the rate of its closure.
The Mutual Influence of Gastrin and Secretin on the External Pancreatic Secretion in Dogs
Authors: Henriksen F. W. , Worning H. 
Published: December 2008

AbstractThe external pancreatic secretion of fluid, bicarbonate and protein in 4 dogs with Thomas type fistulae, has been studied in response to secretin (1 U/kg b.w.), gastrin (2 U/kg b.w.) and combined secretin–gastrin stimulation. Gastrin exerted a stimulating effect on the pancreatic secretion of fluid, bicarbonate and protein and increased the bicarbonate concentration in the juice significantly above basal level. The combined effect of secretin and gastrin on the secretion of fluid, bicarbonate and protein did not differ from the summarized effect of the two agents given separately. Potentation between secretin and gastrin was not demonstrated.
Colour Specific Features of Visual Cortical Responses in Man Evoked by Monochromatic Flashes
Authors: Cigánek Leodegar , Ingvar David H. 
Published: December 2008

AbstractIn 16 normal human subjects a study was made of averaged responses in the occipital regions to monochromatic flashes of 15 different wavelengths with equal energy. The responses to monochromatic flashes were found to have the same principal components as those previously shown in responses to white light. With low intensity flashes of equal energy, the latencies of all components were shortest in the middle range (514–576 mix), longer in the blue, and longest in the red end of the spectrum. With high intensity stimuli, the latencies were in general shorter, and did not vary with wavelength. The high variability of the amplitudes of the evoked responses made it difficult to correlate amplitude with wavelength. However, some individual curves, as well as the average amplitude/wavelength curve for the whole group of 16 subjects, showed partly significant peaks at 453–475, 551 and at 615 mix, a finding which appears to support the existence of a trichromatic colour receptor mechanism in man. One group of the subjects showed a strikingly stable form of the evoked responses, but varying amplitudes of separate components at different wavelengths. Another group showed very stable forms of the responses which appeared specific to wavelength.
Intercostal and Cerebellar Influences on Efferent Phrenic Activity in the Decerebrate Cat
Authors: Decima Emilio E. , Euler Curt von 
Published: December 2008

AbstractThe intercostal‐to‐phrenic reflex connections, previously studied only in spinal preparations, have now been further analyzed in decerebrate cats and rabbits. The early excitatory part of the response was of the same nature as the corresponcling response component in spinal preparations. The subsequent inhibitory phase was due both to post‐firing depression, as in the spinal state, and to active inhibition. The responses in decerebrate animals showed marked respiratory variations with almost complete abolishment of the excitatory component in the end‐expiratory phase. In the decerebrate preparation the responses from the different portions of the diaphragm showed qualitative differences which disappeared after spinalization. Further signs of differentiated intercostal‐to‐phrenic relations were obtained by stimulating different intercostal nerves. Stimulation of the anterior lobe of cerebellum exerted pronounced effects both on the respiratory phrenic activity–inhibition, sometimes followed by post‐tetanic facilitation–and on the intercostal‐to‐phrenic reflex–removing the inhibition in the end‐expiratory phase. Some of the features of the synaptic organization of the phrenic nucleus are discussed.
Proximal Tubular Reabsorption in the Rat Kidney as Studied by the Occlusion Time and Lissamine Green Transit Time Technique
Authors: Bojesen E. , Leyssac Paul P. 
Published: December 2008

AbstractProximal reabsorption rate, determined as the reciprocal of the occlusion time (1/OT), varied in direct proportion to the inulin clearance (Cin) in the range between 1.6 and 0.7 ml/min g KW in nondiuretic rats. Within this range transit time varied from 10 to 24 sec in direct proportion to the occlusion time; the OT/TT ratio averaged 1.10 ± 0.1 (SD). Proximal intra‐tubular pressure averaged 12.4 ± 0.8 mm Hg and did not correlate with CinBelow inulin clearance of 0.7 ml/min g KW transit time (TT) was further increasing from 24 to 44 sec while the OT remained unchanged, thus the OT/TT ratio was decreasing. Proximal intratubular pressure averaged 11.5 ± 0.3 mm Hg.Previous estimates of proximal luminal radius from photomicrographs are revised and a more correct value of about 14 μ was found. The length of the proximal segment, as measured in microdissected nephrons, was 10.4 and 10.5 mm in superficial and juxtamedullary nephrons, respectively. Reflux from more distal segments represented an error of no more than 12 % in estimation of proximal reabsorption rate from the measured OT.The relationship between OT, TT, linear velocity of flow, and tubular fluid/plasma inulin ratio (F/Pin) at 60 % proximal length are derived in quantitative terms. OT/TT = l/ln(F/Pin). From the corrected OT/TT ratio the F/Pin ratio was calculated from values obtained in control rats (“state A”), in rats with partial constriction of the renal artery (“State B”), and in rats with elevated intratubular pressure and urine flow (“State C”).
On the Mechanism of Action for the Effect of Cholecystokinin on the Choledochoduodenal Junction in the Cat
Authors: Hedner Pavo , Rorsman Gunne 
Published: December 2008

AbstractThe resistance of the choledochoduodenal junction was studied by measuring the flow from the common duct into the duodenum under constant infusion pressure and by measuring the intracholedochal pressure under constant infusion rate. It is concluded that the choledochoduodenal junction contains a real sphincter where the normal contracted state depends on an intact cholinergic nerve supply. As the effect of cholecystokinin on the small intestine is mediated by a cholinergic pathway, a similar mechanism of action for its effect on the choledochoduodenal junction was questioned. However, cholinergic and adrenergic mechanisms could be blocked by atropine and reserpine without affecting the antagonism of cholecystokinin to the contraction of the spincter elicited by bradykinin. Thus the effect of cholecystokinin on the choledochoduodenal junction seems to be a direct one and related rather to its effect on the gall‐bladder than to its effect on the small intestine.
Proteolytic Inhibitors in Plasma from Man Treated with a Protease from Aspergillus oryzae
Authors: Jürgens J. , Lindvall S. , Magnuson O. , Orth K. 
Published: December 2008

AbstractThe level of total, heat stable and heat labile inhibitors of a proteolytic enzyme from Aspergillus oryzae‐protease I‐have been studied in plasma from eight patients. After treatment of these patients by infusions of 150 mg of the proteolytic enzyme in 5 % levulose solution, the change in the level of the different inhibitors have been estimated. It has been shown that there is a lowering of the total inhibitors content after each infusion. This decrease is only partly compensated for by the day following the first infusion. After the forthcoming infusions the decrease is completely compensated for resulting in a level before each subsequent infusion which is lower than that before commencement of treatment. This remaning decrease can be attributed to the heat stable inhibitor. A possible mechanism for the thrombolytic effect of the protease is mentioned.
A Method for the Simultaneous Determination of 5‐Hydroxy‐3‐Indole‐Acetic Acid (5‐HIAA) and 5‐Hydroxytryptamine (5‐HT) in Brain Tissue and Cerebrospinal Fluid
Authors: Jonsson John , Lewander Tommy 
Published: December 2008

AbstractA method is described for the isolation of 5‐HIAA in brain tissue extracts or cerebrospinal fluid by use of a Sephadex G‐10 column. The eluate is taken for fluorimetric determination of 5‐HIAA in 3 M hydrochloric acid. Tissue blanks are obtained by destruction of 5‐HIAA with potassium ferricyanide plus UV irradiation or with hydrogen peroxide. Recovery of 5‐HI.4A from brain extracts was above 90 %. The sensitivity of the method allows quantitative determination of about 50 ng of 5‐HIAA in a tissue extract. 5‐HT in the effluent and washings from the Sephadex G‐10 column was isolated on a weak cation exchange resin and determined fluorimetrically (AndCn and Magnusson 1967). Recovery of 5‐HT added to brain extracts was 85 %. Determination of 5‐HIAA in 3–5 ml samples of human cerebrospinal fluid could be performed with the present method with a recovery of 83 %.
Species Distribution of Sympathetic Cholinergic Vasodilator Nerves in Skeletal Muscle
Authors: Bolme Per , Novotný Jozef , Uvnäs Börje , Wright Peter G. 
Published: December 2008

AbstractThe lumbar sympathetic chain was electrically stimulated in different species before and after blocking the adrenergic vasoconstrictor nervous response. Blood flow in the hind limb skeletal muscles was measured. In all species studied, fox, sheep, goat, monkey (five different strains), polecat, rat, badger, opossum rat and hare, stimulation of the lumbar chain before adrenergic blockade resulted in a vasoconstriction. After blocking the vasoconstrictor nervous response stimulation elicited a blood flow increase in fox, sheep and goat. After atropine, the response to stimulation was blocked, indicating that sympathetic cholinergic nerves had been activated. In the other species studied no vasodilator response was observed upon sympathetic chain stimulation. The results suggest that the role attributed to the vasodilator nerves, anticipatory to muscle exercise, are played by other mechanisms in species lacking sympathetic cholinergic vasodilator nerves.
A Comparison of Blood Viscosity Measured In Vitro and in a Vascular Bed
Authors: Djojosugito A. M. , Folkow B. , ÖBerg B. , White S. 
Published: December 2008

AbstractBlood viscosity in vivo (“apparent viscosity”) and its variations with flow rate was analyzed in the maximally dilated calf muscle vascular bed of the cat by comparing pressure‐flow relationships for blood and a Newtonian fluid (dextran‐Tyrode) over a flow range between 60 and 0.2 ml/min × 100 g tissue. Viscosity in vitro for the same perfusates was measured in a cone‐plate viscometer.—Apparent viscosity was much lower (approximately 50 %) than in vitro values at high shear rates, with less variation between animals. It increased with decreased flow but was as a maximum only doubled, which occurred at flows around 0.5 ml/min × 100 g. Since such small flows normally occur in constricted vessels with higher flow velocities than at maximal dilatation, the range of viscosity changes with flow in the intact circulation is probably decidedly smaller. The steep rise of viscosity in vitro at quite low shear rates had no counterpart in vivo; in fact, viscosity then tended to fall again. The discrepancies between blood viscosity in vivo and in vitro seem to be related to vascular dimensions, favouring “bolus flow” and hence low regional viscosity in the most narrow vessels, which may become more pronounced at further luminal reduction, active or passive.Addition of high molecular weight dextran (HMD) raised apparent viscosity to seemingly high levels at low flows. However, to a considerable extent this appears to be due to cell aggregation and plugging of microvessels rather than to a genuine increase of blood viscosity.
The In Vivo CO2 Buffer Capacity of Rat Brain Tissue under Carbonic Anhydrase Inhibition
Authors: Kjällquist A. , Messeter K. , Siesjö B. K. 
Published: December 2008

AbstractThe effect of acetazolamide upon the in vivo CO2 buffer capacity of rat brain tissue was investigated by injecting the animals with the drug in two doses of 50 mg/kg each before they were anesthetized and subsequently exposed to various CO2 tensions for 40–60 min. Acetazolamide was found to give a marked lowering of the CO2 buffer capacity. Thus, the intracellular buffer capacity, calculated as β=Δlog pCO2/ΔpHi, was found to be about 1.4, and thus considerably lower than the intracellular CO2 buffer capacity of animals not given acetazolamide but otherwise treated in an identical way (β= 2.3, see Kjällquist, Nardini and Siesjö 1969 a). The results indicate that acetazolamide interferes with an active transport of hydrogen ions between cells and the extracellular fluids which is dependent on carbonic anhydrase.
The Catechol Amine Content of the Bull Retractor Penis Muscle
Authors: Klinge Erik 
Published: December 2008

AbstractThe noradrenaline, adrenaline and dopamine content of the bull retractor penis muscle was determined. Dowex 50‐X4 ion exchange columns were used for the purification procedure and for the separation of dopamine from the other catechol amines. The muscle contains con siderable amounts of noradrenaline but it probably is devoid of adrenaline. The dopamine content is about 10 % of that of noradrenaline. It seems possible that the impulses main taining the almost continuous contraction of the bull retractor penis muscle are conducted along sympathetic nerves.
On the Mechanism of Depletion of Noradrenaline Stores by Iso‐Monomethylnicotinium Bromide
Authors: Hedqvist P. 
Published: December 2008

AbstractThe quaternary nicotine analogue iso‐monomethylnicotinium bromide (IMN) inhibits the uptake of noradrenaline (NA) in the perfused guinea‐pig heart without causing any change in the distribution between the particulate and soluble fractions of the NA taken up. In the isolated perfused cat spleen IMN increases the resting outflow of NA, and the NA overflow response to nerve stimulation, while that to tyramine (TA) is reduced. IMN does not affect release or uptake of NA in isolated splenic nerve granules, or the formation of NA from tyrosine in this system.It is suggested that IMN causes depletion of NA stores both by releasing NA, probably from extragranular sites, and by inhibiting reuptake of the NA released.
Reflex Changes in Sympathetic Activity and Arterial Blood Pressure Evoked by Afferent Stimulation of the Renal Nerve
Authors: Aars H. , Akre S. 
Published: December 2008

AbstractThe effects of afferent stimulation of renal nerves on efferent sympathetic activity and systemic blood pressure were studied in anesthetized rabbits. In most animals, afferent impulses pro duced reduction or abolition of sympathetic activity and a fall in blood pressure. High fre quencies of stimulation (20–30 pulses/sec or more) caused a more marked and long‐lasting depression of efferent activity and blood pressure than low frequencies. The highest sensitivity of blood pressure to variations in stimulation frequency was found in the range of 1–10 pulseslsec. Stimulation of the renal afferents had qualitatively the same effect on sympathetic activity and blood pressure as aortic nerve stimulation, but for the aortic nerve, higher stimu lation frequencies were required to obtain the same reduction in blood pressure. It is con cluded that afferent activity in renal nerves has a predominantly inhibitory effect on vasomotor activity, resulting in a fall in blood pressure.
Secretive Pressure Exerted by the Stimulated Nasal Salt Gland in Larus Argentatus (Herring Gull)
Authors: Håkansson C. H. , Malcus B. 
Published: December 2008

AbstractInvestigations of the dynamics of the nerve stimulated nasal salt gland of the Larus argentatu (Herring Gull) have shown that intraglandular duct anastomoses permit the gland to secret through one duct if the other is occluded. The force to extrude the secretion by maxima stimulation and uncatheterized ducts is lower than 40 mm H2O. The pressure force when botl ducts were occluded was measured to 430 mm H2O maximally.
Transmembrane Transport of Chloride and Iodide in Proximal Rat Tubules
Authors: Danielson B. G. , Person E. , Ulfendahl H. R. 
Published: December 2008

AbstractThe transport mechanism for chloride across the proximal tubular epithelia in the rat was investigated with a free‐flow micropuncture technique. The purpose of the investigation was to determine whether there is an active carrier system for chloride transport out of the tubule with different affinities for different halides and higher for iodide than for chloride. The TF/P values for sodium, potassium, chloride and iodide were determined simultaneously. The TF/P value for chloride (1.15) was significantly lower than the TF/P value for iodide (1.73). It was concluded that there is no evidence of an active transport system and that chloride and iodide are transported passively out of the tubular lumen, the permeability for iodide being somewhat lower than for chloride.
Pulmonary Gas Exchange as Influenced by G‐Induced Shifts in Central Blood Volume
Authors: MCosenhamer G. R. 
Published: December 2008

AbstractExperimental observations are presented on interrelationships between G‐induced displacements of blood volume and pulmonary function. A statistically significant correlation is demonstrated between the changes in the “central blood volume” and venous admixture in the lungs. A possible explanation may be that a large G‐induced displacement of blood volume from intra‐ to extrapulmonary blood vessels results in a less marked pa+ distension of the dependent pulmonary blood vessels, and therefore in higher regional V/Q ratios, than if the G‐induced drain of blood out of the lungs is pronounced. This explanation is supported by previous observations that G‐induced venous admixture increases when peripheral pooling of blood is counteracted by the action of the leg muscle pump.
Relaxing and Metabolic Actions of ACTH in Rabbit Colan
Authors: Anderson Rolf , Mohme‐Lundholm Ella , Svedmyr Nils , Vamos Nandor 
Published: December 2008

AbstractAndersson, R., E. Mohme‐Lundholm, N. Svedmyrand N. Vamos,Relaxing and metabolic actions of ACTH in rabbit colon. Acta physiol. scand. 1971.81. 11–17.ACTH in the dose range of 0.15–4.60 IU/ml relaxed the circular muscular layer of rabbit colon contracted by carbacholine. The content of cyclic AMP was doubled. There was an activation of phosphorylaseawhich gave the same dose‐effect and time‐effect curves as thc relaxing action. The hexose phosphate and creatine phosphate contents of the muscle also increased. The relaxing and metabolic actions of ACTH were completely blocked by an adrenergic β‐receptor blocking agent (sotalol). The type of inhibition was competive. The relaxing action of ACTH was potentiated by theophylline and puromycin, agents which inhibit the enzymatic hydrolysis of cyclic AMP. The relaxing and metabolic actions of ACTH were similar to those of isoprenaline. They could be reproduced by cyclic AMP. In contrast to cyclic AMP and isoprenaline, ACTH did not decrease the adenosine triphosphate contcnt of thc muscle. It is suggested that the relaxing action of ACTH is mediated by thc adcnyl cyclase‐cyclic AMP system.
Canjoint Action of Sodium and Angiotensin on Brain Mechanisms Controlling Water and Salt Balances
Authors: Andersson B. , Eriksson L. 
Published: December 2008

AbstractAndersson, B. and L. Eriksson, Conjoint action of sodium and angiotensin on brain mechanisms controlling water and salt balances. Acta physiol. scand. 1971. 81. 18–29.The effects on water and salt balances of a simultaneous infusion of angiotensin and hypertonic NaCl into the 3rd brain ventricle were studied in goats in normal water balance and in hydrated animals. For comparison similar infusions of angiotensin alone (solved in slightly hypotonic saline) and of hypertonic NaCl were made. Like the hypertonic NaCl, 30 min infusions of angiotensin alone induced drinking in animals in normal water balance, and an inhibition of the water diuresis in the hydrated goat. The simultaneous infusion of both substances resulted in a marked potentiation of the dipsogenic and the antidiuretic effects. A possible explanation may be that angiotensin facilitates the transport of Na+ into brain cells regulating thirst and ADH release, and that the intracellular Na+ concentration rather than strictly osmotic factors determines the activity of these cells. In the hydrated goat a central effect of angiotensin strongly enhanced the natriuretic response to intraventricular infusions of hypertonic NaCl, and extreme natriuresis developed as result of the combined infusions in hydrated, salt‐supplemented animals. During normal water balance this sodium‐angiotensin synergism was less obvious, which suggests that both an expanded fluid volume and an elevated intracellular Na+ concentration are needed for optimal activation of a brain mechanism which stimulates renal Na' excretion, The time course of the centrally induced natriuresis indicates that the effect on the kidney may be mediated by a humoral agent.