bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Varied Cerebrospinal Fluid Pressure on Cerebral Blood Flow in Dogs
Authors: Häggendal Egil , Löfgren Jan , Nilsson Nils Johan , Zwetnow Nicolaus N. 
Published: December 2008

AbstractEffects of short‐term variations in cerebrospinal fluid pressure on cerebral blood flow in dogs were measured with the radioactive krypton clearance technique of Lassen et al. The cerebrospinal fluid pressure was increased stepwise by infusion of artificial cerohrospinal fluid, the pressure range from ‐15 to +150 mm Hg being investigated. The cerebral blood flow remained virtually stable, when the induced cerebrospinal pressure was lower than about 100 mm Hg. At higher values the cerebral blood flow began to fall. Thus, the existence of flow auto‐regulation was demonstrated also for the situation when perfusion pressure is reduced by a rise of the intracranial pressure. At very high cerebrospinal fluid pressures an additional reaction appeared in the form of a rise in the systemic arterial blood pressure. A discussion of the relative roles of these two regulating mechanisms is given.
Prolonged Cerebral Hyperemia after Periods of Increased Cerebrospinal Fluid Pressure in Dogs
Authors: Häggendal Egil , Löfgren Jan , Nilsson Nils Johan , Zwetnow Nicolaus N. 
Published: December 2008

AbstractIn 23 dogs the cerebral blood flow was measured with the intra‐arterial radioactive injection technique during and after the application of a high cerebrospinal fluid pressure by infusion of artificial cerebrospinal fluid into the subarachnoid space. Increased cerebral blood flow was observed in most cases when the cerebral perfusion pressure was restored after a period with cerebrospinal fluid pressure over 50 mm Hg. The hyperemia always occurred if during the period of high intracranial pressure the blood flow had been reduced below the control value: in a few cases it appeared also without a preceding flow reduction. In almost all cases there was a marked tendency to normalization of the blood flow after the initial period of hyperemia. No chemical factors in the artificial cerebrospinal fluid could be made responsible for the phenomenon described, which is attributed to a disturbance of cerebrovascular function, impairing the ordinary flow autoregulation.
Some Characteristics of Lipolysis in Rabbit Adipose Tissue. Effects of Noradrenaline, ACTH, Theophylline and Prostaglandin El
Authors: Micheli Horace 
Published: December 2008

AbstractPerirenal adipose tissue from rabbits of different strains was incubated in vitro and the glycerol release determined to evaluate the lipolysis. Noradrenaline was found to stimulate lipolysis, but to a lower degree than ACTH. From one strain of rabbits it was apparent that lighter (younger) rabbits were more responsive to noradrenaline than heavier (older) animals, some of which were completely unresponsive to the catecholamine. Theophylline as well as PGE, were ineffective when added alone to the incubation medium. However, theophylline increased the glycerol release induced by noradrenaline and low concentrations of ACTH and PCE, inhibited lipolysis under these conditions. The results suggest that there is a low rate of formation of cyclic AMP in rabbit adipose tissue under basal conditions of incubation while the hormonal stimulations might well operate by means of increasing the accumulation of cyclic AMP.
Vasoactivity of Adenine Nucleotides Released in vitro from Blood Cells by Thrombin
Authors: Swedenborg Jesper 
Published: December 2008

AbstractSmall amounts of thrombin infused into the Cenioral artery of dogs decrease the peripheral vascular resistance, due to release of adenine nucleotides from blood cells.The present study was designed to determine the source of vasoactive adenine nucleotides released from blood cells by thrombin. Washed human platelcts, red cells and white cells were incubated with thrombin and the resulting supernatant was tested for vasoactivity. Dog platelet rich plasma and platelet poor plasma incubated with thrombin was also assayed for vasoactivity, as well as hemolysed red cells. Supernatants from incubated platelets showed strong vasocativity which disappeared after exposure to ADP‐ase and ATP‐ase (Apyrase). Supernatants from red cells and white cells were not vasoactive. Platelet rich plasma incubated with thrombin was highly vasoactive in contrast to platelet poor plasma treated similarly. Hemolysed red cells were highly vasoactive and this vasoactivity also disappeared after treatment with Apyrase. It is concluded that small amounts of thrombin release adenine nucleotides from the platelets. This does not occur when red cells or white cells are acted upon by thrombin although the major supply of the nucleotides is to be found in the red cells.
Myoneural Ultrastructure and Cholinesterases after Tetrodotoxin Treatment
Authors: Teräväinen H. 
Published: December 2008

AbstractIntraperitoneally injected tetrodotoxin, irrespective of the dose given, caused no changes in the ultrastructure of the myoneural junctions of the rat striated muscle, or in their histo‐chemically demonstrable acetyl (E.C. 3.1.1.7.) or non‐specific (E.C. 3.1.1.8.) cholinesterase activity.
Characterization of Ovarian RNA
Authors: Ahrén Kurt , Hamberger Lars , Jarlstedt Jan , Nilsson Lars 
Published: December 2008

AbstractOvaries were obtained from 24–25 day old Sprague‐Dawley rats. Groups of 20 ovaries were collected corresponding to a wet weight of 100–120 mg, and incubated for 20, 30, 60 and 240 min at 37° C in Krebs bicarbonate buffer containing 5.5 mM glucose and uridine‐3H. Following incubation, ovarian RNA was extracted with a modified phenol extraction method described in detail. Fractionation was made by composite agarose‐polyacrylamide gel electrophoresis which gave good separation and high resolution of the various RN.4 fractions. Ovarian RNA separated in four well‐defined fractions classified as 28S, 18S, 5s and 4s. This classification was based upon comparisons with simultaneously run liver RNA. In addition to the four main fractions. a weak band just before 28S and two smaller bands between 28S and 18S were consistently observed. Labelling of ovarian RNA with uridine‐3H showed a polydisperse pattern after the shorter incubation periods with most of the radioactivity concentrated to RNA fractions of molecular weights higher than 28S, but also clear labelling of the 5S—4S region. After 60 min, radioactivity peaks were also associated with the 28S and 18s fractions and with fractions between those, while after 240 min incubation, the radioactivity was concentrated to the four main fractions. The incorporation of radioactivity was found to be markedly decreased in presence of actinomycin D.
Dopamine Secretion from the Isolated Perfused Sheep Adrenal
Authors: Lishajko F. 
Published: December 2008

AbstractIsolated sheep adrenals, perfused with Tyrode solution, release in addition to adrenaline (A) and noradrenaline (NA) small amounts of dopamine (DA) into the effluent. The amines appeared in the perfusate even in the absence of C1 or Ca2+ions. Addition of ACh to the per‐fusion fluid increased NA and A in the effluent 2–3 times and DA about 5 times. In calcium and chloride free Tyrode solution carbachol increased secretion 1.7–2.7 times for all 3 amines. Reintroduction of Ca2+into the media increased the response to ACh and carbachol 5–7 times. Injection of Ca2+into the perfusion fluid further increased the secretory response to simultaneously added. ACh and carbachol 14–18 times for all 3 amines.
Steps in Impulse Generation in the Isolated Muscle Spindle
Authors: Ottoson D. , Shepherd G. M. 
Published: December 2008

AbstractThe interrelationship between the different steps in the generation of the afferent discharge was studied in isolated frog spindles. Attention was focused on the prepotential and its relation to the receptor potential and to the frequency of the impulse divcharge during various phases of controlled stretches. It was found that the rate of rise of the prepotential increased linearly with increasing amplitude of the underlying receptor potential. For stretches of a given strength the rate of rise increased with the velocity of the stretch. The frequency of the discharge was directly related to the rate of rise of the prepotential. A similar relationship was found for the discharge frequency and the amplitude of the receptor potential. The results thus show that there is a close interrelationship between the three main stages of impulse generation. This finding explains the ability of the spindle to pass on faithfully, in the frequency Characteristics of the impulse discharge, information about the properties of the applied stretch.
Chylomicron Size and its Relation to the Composition of Dietary Fat in the Rat
Authors: Sylvén Christer 
Published: December 2008

AbstractThoracic duct cannulated rats were fed 50 μmoles of radioactive cholesterol dissolved in medium chain triglyceride (MCT), hydrogenated coconut oil (HCOCO) or triolein. Lymph was sampled and fractionated with ultracentrifugation and gel chromatography. The amount of lymph lipoproteins was estimated by their lipid content. Gel chromatography showed that there was a continuous distribution of lymph lipoproteins according to molecular size. The transport of chylomicron lipoproteins i.e. those of Sf>400 increased with fatty arid chain length of the triglyceride used. When MCT or HCOCO were administered the transport of lipoproteins 400>Sf>20 increased. Administration of triolein gave the same transport as HCOCO. While the transport of both lipoprotein classes was lowest when MCT was used. this triglyceride induced the highest transport of cholesterol in lipoproteins 400>Sf>20. This was reflected in the percentage composition of the lipoprotein lipid. It contained more cholesterol and less triglyceride as compared to the other dietary conditions. Exogenous cholesterol was transported in both lipoprotein fractions.
Transport of Glucose, Sodium, Chloride and Potassium between the Cerebral Ventricles and Surrounding Tissues in Cats
Authors: Brondsted H. E. 
Published: December 2008

AbstractThe ventriculo‐aqueductal perfusion technique was used in order to study the mechanism for transport of glucose, sodium, chloride and potassium between the cerebral ventricles and surrounding tissues in cats. The inflow perfusion fluid contained U14C‐D‐glucose and un‐labelled D‐glucose. With D‐mannose or D‐xylose in the inflow, the unidirectional flux of glucose from the cerebral ventricles was inhibited competitively. Ouabain in the inflow (10‐7M or 10–45M) and potassium‐free inflow reduced the rate of cerebrospinal fluid formation while the tissues lost potassium and gained sodium and chloride. The presence of ouabain reduced the unidirectional flux of glucose from the cerebral ventricles. The effects increased using higher concentrations of ouabain (up to 5 times 10‐5M). Injections of increasing amounts of ouabain into the internal carotid artery had 110 effects upon the above mentioned variables. The results support the idea that ouabain‐sensitive carrier‐mediated transport of glucose from the cerebral ventricles may be connected with the mechanism for active transport of ions.
Effects of Vasoactive Drugs on Circulation in Canine Subcutaneous Adipose Tissue
Authors: Fredholm B. B. , ÖBerg B. , Rosell S. 
Published: December 2008

AbstractThe circulatory effects of acetylcholine, bradykinin, isoprenaline, histamine, 5‐hydroxytrypt‐amine (5‐HT), noradrenaline and prostaglandin Ei (PGE1) were studied in the canine subcutaneous adipose tissue. PGE1produced clearcut vasodilatations at calculated blood concentrations as low as 10‐9M and was found to be the most potent of the drugs tested. PGE1was about 1000 times more potent than acetylcholine and about 10 times more potent than histamine. 5‐HT induced a moderate blood flow increase with no change or a decrease of tissue volume, indicating a constriction of the venous section. The vascular responses to noradrenaline infusions were essentially similar to those produced by sympathetic nerve activation,i.e. constriction of arterioles and veins and a markedly increased capillary filtration coefficient (CFC). Histamine and bradykinin induced increases of CFC of the same magnitude as did sympathetic nerve stimulation, whereas acetylcholine, isoprenaline, 5‐HT and PGE1induced smaller increases of CFC. Sympathetic nerve stimulation superimposed upon infusions of the latter drugs produced a further marked increase of CFC, while nerve stimulation applied during a period of histamine or bradykinin infusion produced no further rise or even a decrease of CFC. It is discussed that the pronounced CFC increase during sympathetic nerve stimulation is due to an increased permeability of the capillary membrane.
Variation in Total Body Water with Muscle Glycogen Changes in Man
Authors: Olsson Karl‐Erik , Saltin Bengt 
Published: December 2008

Abstract19 subjects performed prolonged heavy arm and leg exercise after which they had a protein and fat diet for three days. Thereafter they switched to a carbohydrate enriched diet during a 4‐day period. The measurements were performed on the 3rd day and then repeated on the 7th day. The glycogen concentration in the thigh and the arm muscles was 4.5 and 2.6 g/kg wet muscle on the 3rd day and increased with the carbohydrate enriched diet to 19.9 and 16.9 g/kg wet muscle, respectively. Body weight increased 2.4 kg during this period of 4 days. The total body water increased 2.2 1 which is assumed to be caused by the glycogen storage in the muscles and the liver. The amount of glycogen stored was calculated to be at least 500 g, which means that 3—4 g of water is bound with each gram of glycogen.
Blood Flow and Oxygen Extraction in the Cat Uvea at Normal and High Intraocular Pressures
Authors: Alm Albert , Bill Anders 
Published: December 2008

AbstractThe rate of blood flow through the uvea and the arterio‐venous O2difference across the uveal tract were determined in cats. The normal rate of blood flow was 1.14 ± 0.23 ml/min and the normal a‐v O2difference was 1.02 ± 0.16 volume per cent. The O2extraction was 8.0 ± 0.6 μl NTP/min. The arterial O2saturation, Po2, Pco2, and pH were 95.6 ± 0.3 per cent, 93 ± 3 mm Hg, 25.8 ± 1.0 mm Hg, and 7.44 ± 0.01 units, respectively. An artificial rise in eye pressure reduced the rate of uveal blood flow and increased the a‐v O2difference. The O2extraction was relatively constant at blood flow rates above 0.3–0.5 ml/min. At lower flow rates the O2extraction decreased in spite of a high venous O2concentration. Blood collected from the choroidal veins had a slightly higher O2concentration than blood collected from the intrascleral venous plexus. A reduction in uveal blood flow, produced by a reduction in the mean arterial blood pressure, reduced the O2content both in blood collected from the choroid and in blood leaving the anterior uvea. The results suggest that at low perfusion pressures there is anoxia in some tissue supplied by the uveal vessels, in spite of a relatively well oxygenated venous blood.
Determination of Cortical Blood Flow in Rabbit Femur by Radioactive Microspheres
Authors: Lunde P. K. M. , Michelsen K. 
Published: December 2008

AbstractThe method for blood flow determination involving measurement of relative radioemission from radioactive microspheres retained in various tissues after intravascular injection has here been applied to minute tissue regions. 85Sr‐labelled plastic microspheres with a diameter of 15 ± 5 μ were injected in a retrograde manner into the aorta in 10 anesthetized adult rabbits. The tissues included in the present study were the m. quadriceps femoris tendon, the cortical bone and the corresponding bone marrow from the left femur diaphysis. The unknown blood flows through these tissue regions were calculated by relating the measured radioactivity from tissue samples to a known blood flow and a known blood radioactivity in cannulated branches from the left posterior tibial artery. The blood flow values estimated by this technique were (g/minxg tissue): Quadriceps femoris tendon ‐0.068 ± 0.044, bone marrow of femur diaphysis ‐0.250 ± 0.146, cortical bone of femur diaphysis ‐0.010 ± 0.007.
Time Relations of Degeneration Mydriasis and Degeneration Vasoconstriction in the Rabbit Ear after Sympathetic Denervation. Effect of Bretylium.
Authors: Bárány Ernst H. , Treister Giora 
Published: December 2008

AbstractRemoval of the superior cervical ganglion in rabbits causes homolateral mydriasis starting about 14 hrs and ending about 32 hrs after the operation. In the external ear a vasoconstriction starts around 20 hrs and ends around 40 hrs after operation. A residual vasoconstriction sensitive to systemic ganglionblocking agents is often seen. Both phenomena are similarly delayed by bretylium. No time difference between the end of vasoconstriction at the base and at the tip of the ear (5–7 cm apart) was observed under conditions where a time difference of 2–3 hrs would have been detected. The conclusion is that the time between operation and transmitter release from the degenerating terminals is longer than is needed for the message of the interruption of the axon to reach the terminals. Time differences between degeneration release of transmitter in different organs may be partly due to intrinsic differences between the populations of terminals.
The Degeneration Contraction of a Sympathetically Innervated Smooth Muscle in the Rat after Reserpine, Inhibition of Monoamine Oxidase or Tyrosine Hydroxylase
Authors: Lundberg Dag 
Published: December 2008

AbstractThe degeneration contraction of the periorbital smooth muscle in conscious rats was measured after treatment with each of 3 different monoamine oxidase (MAO) — inhibitors, reserpine or the methylester of α‐methylthyrosine. Pheniprazine (10 mg/kg), nialamide (100 or 200 mg/kg) pargyline (100 or 200 mg/kg) given at the time of denervation and pargyline (100 or 200 mg/kg) given at 10 hrs after denervation significantly increased the size of the degeneration contraction. 200 mg/kg of pargyline tended to delay the onset of the contraction. However, pheniprazine, nialamide or pargyline at 100 mg/kg started it prematurely. An injection of reserpine (1 mg/kg) given at 2–3 hrs before the expected start of the degeneration transmitter release did not induce any excitatory effect and abolished the degeneration contraction. Inhibition of the synthesis of noradrenaline by the methylester of 1‐α‐methyltyrosine (H 22/07) given at the time of denervation or 10–12 hrs later did not influence the size or the time course of the degeneration contraction. It is concluded that: — The degeneration transmitter release is normally influenced by functional MAO. — Since the potent MAO‐inhibitors studied did not consistently delay the start of the degeneration contraction, it does not seem reasonable that bretylium, which earlier has been found both to possess MAO‐inhibiting and delaying effect, induces a delay only by inhibiting intraaxonal MAO. — There is no significant contribution of newly formed noradrenaline to the degeneration contraction.
Adrenergic Excitatory Influences on Initiation and Conduction of Electrical Activity in the Rat Portal Vein
Authors: Ljung Bengt , Stage Lars 
Published: December 2008

AbstractThe longitudinal smooth muscle of the rat portal vein shows synchronized spontaneous contractions. Both initiation and propagation of this activity are of myogenic nature. Under the influence of noradrenaline (NA), or postganglionic nerve stimulation, the contraction frequency is known to increase markedly. In order to analyse pacemaker function and synchronization of activity in the isolated portal vein, both during spontaneous activity and during NA induced excitation, a method was designed which allowed simultaneous recording of the mechanical contractions and of the electrical activity from three separate areas in the preparation.Spontaneous, intermittent bursts of electrical spike activity spread over the preparation at a velocity of 5 to 30 mm/sec. Each propagated burst was associated with a mechanical response. Evidence is presented indicating that the individual spike potentials within a burst were propagated. Administration of exogenous NA markedly increased the frequency of burst discharge from an active pacemaker area, so that the preparation became synchronously driven at a higher rate, eventuelly leading to a maintained tetanus. In addition, propagated activity from “ectopic” pacemaker areas appeared, which caused irregular contractile responses. Qualitatively similar activity patterns were obtained by tyramine administration. The pronounced synchronization, and the increase in frequency of burst discharge elicited by such release of endogenous NA, suggest that myogenic propagation plays a most important role in the effectiveness of nervous control of this type of vascular smooth muscle.
Projections to the Cerebral Cortex from Afferents of the Interosseous Nerves of the Cat
Authors: Silfvenius H. 
Published: December 2008

AbstractEvoked focal potentials from the contralateral fore‐ and hindlimb interosseous nerves Int.f. and Int.h. as well as from Pacinian afferents were recorded in sensorimotor cortex and in S II in cats anaesthetized with chloralose. Low threshold, short latency potentials from Int.f. were evoked in the lateral sigmoid gyrus, in the region of the post cruciate dimple, in the rostral bank of the lateral ansate sulcus, in the lower bank of the anterior suprasylvian sulcus and in S II. The shortest latencies varied between 5.0–6.0 msec. Mechanical stimulation of dissected clusters of Pacinian receptors in the interosseous region evoked cortical responses in the same areas with slightly longer latencies. Low threshold electrical stimulation of Int.h. afferents evoked in addition to the known projection to S II (McIntyre 1962) initially positive potentials in two loci of the postsigmoid gyrus, one on the dorsal, the other on the medial aspect of the hemisphere. The latencies in these loci were as short as those in S II. i.e. 9.5–10.0 msec. Zonal convergence between projections from interosseous and Group I muscle afferents was observed. The Int.f. path ascends in the dorsal column. A cortical potential was however, evoked in the postsigmoid gyrus by electrical stimulation of high threshold Int.h. afferents after transection of the dorsal columns at cervical level.
Quantitative Correlation between Degranulation and Histamine Release Following Exposure of Rat Mast Cells to Compound 48/80 in vitro
Authors: Nósal Radomír , Slorach Stuart A. , Uvnäs Börje 
Published: December 2008

AbstractThe relationship between the release of histamine and 35S‐labelled heparin from mast cells exposed to compound 48/80 in vitro has been studied in order to elucidate the mechanism of histamine release induced. The cells were taken from rats injected 3, 6, 12 or 20 days earlier with Na235SO4. A good correlation was found between the two release curves. From studies of the 35S/protein ratio in the extruded granules and granules obtained by water lysis of the washed compound 48/80‐treated cells it appears that the 35S‐labelled heparin was first evenly distributed with respect to the granule protein 12 to 20 days after injection. Using cells taken after such an interval the ratio percentage histamine release/percentage 35S release was found to be 1.1–1.4. We conclude from these results and from the similarity between the time courses of histamine and 35S release that the mechanism of histamine release induced by compound 48/80 involves an initial extrusion of histamine‐cotnaining granules, followed by an exchange of histamine in the extruded granules and cations in the extracellular medium.