bluuebunny/crossref_metadata_2025_split huggingface dataset:
Airway Effects of Slow Reacting Substance, Prostaglandin F2αand Histamine in the Guinea‐Pig
Authors: Strandberg Kjell , Hedqvist Per 
Published: December 2008

AbstractSRS, PGF2α, and histamine were administered intravenously or as aerosols to artificially ventilated guineapigs in order to assess their capacity to affect tracheal insufflation pressure measured by means of Konzett‐Rössler technique. Independently of route of administration all three compounds increased tracheal insufflation pressure, SRS being the most potent one. Bilateral cervical vagotomy did not alter the effect. Relative to histamine SRS and PGF2αwere considerably more active by aerosol administration than by intravenous injection. The aerosols had little or no effect on systemic blood pressure. On intravenous injection, histamine decreased and SRS adn PGF2αincreased arterial blood pressure in a dose‐dependent fashion. The airway effects of histamine were correlated to those on blood pressure whereas with SRS and PGF2αthis was not seen when the blood pressure effects were marked. Preadministration of adrenaline or isoprenaline as aerosols antagonized the increase in insufflation pressure, but not the effects on blood pressure, produced by intravenously injected histamine of PGF2α.It is concluded that SRS, PGF2αand histamine on intravenous or aerosol administration increase tracheal insufflation pressure in the guinea‐pig mainly by an action on airway tone. The data emphasize that SRS is a potent bronchoconstricting agent, possibly of pathophysiological significance in guinea‐pig anaphylaxis.
Reflex Inhibition of the Slowly Adapting Stretch Receptors in the Intact Abdomen of the Crayfish
Authors: Njå A. , Walløe L. 
Published: December 2008

AbstractThe reflex inhibition of abdominal stretch receptors in crayfish was studied by controlled passive flexion of individual abdominal joints. The results are very similar to those obtained by electrical or mechanical stimulation of individual stretch receptors in immobilized abdomens. Reflex effects from posterior to anterior abdominal segments are somewhat stronger than in the opposite direction. Flexion of one abdominal joint excites the stretch receptors of that joint and inhibits the stretch receptors in neighbouring abdominal segments. Without reflex inhibition flexion of one abdominal joint excites the stretch receptors in several abdominal segments.
Plasma Renin Activity and in vitro Synthesis of Aldosterone by the Adrenal Glands of Rats with Spontaneous, Renal, or Pinealectomy‐Induced Hypertension
Authors: Karppanen Heikki , Lahovaara Salme , Männistö Pekka , Vappatalo Heikki 
Published: December 2008

AbstractIn the present study a comparison was made on the role of the renin‐aldosterone system in rats with various forms of experimental hypertension (pinealectomy‐induced, renal and spontaneous). The plasma sodium and potassium concentrations as well as renin activity were measured. The in vitro production of aldosterone by quartered adrenal glands of these rats was also determined. 5 weeks after the operations the blood pressure of the pinealectomized and renal operated rats was significantly increased. The plasma sodium concentration did not differ in various groups, but that of potassium was decreased in the renal hypertensive animals. The plasma renin activity of the pinealectomized rats was elevated while in other forms of hypertension it was at the control level. The basal aldosterone production by the adrenal quarters was equal in all the groups. ACTH, dibutyryl cyclic adenosine‐3′,5′‐monophosphate (DBA) and 5HT stimulated the aldosterone production. The responses to ACTH and DBA were greater in the adrenals of renal hypertensive rats than in the other forms of hypertension or in the controls. We suggest that the renin‐aldosterone system is of importance in the maintenance of renal hypertension, while in pinealectomy‐induced hypertension elevated plasma renin activity reflects an increased sympathetic activity which probably is the main cause of hypertension in these animals.
Prostaglandin Endoperoxides IX. Characterization of Rabbit Aorta Contracting Substance (RCS) from Guinea Pig Lung and Human Platelets
Authors: Svensson Jan , Hamberg Mats , Samuelsson Bengt 
Published: December 2008

AbstractMaterial causing contraction of the isolated rabbit aorta (rabbit aorta contracting substance, RCS) was released from guinea pig lung following perfusion with arachidonic acid and from human blood platelets after addition of thrombin to induce aggregation. Prostaglandin endoperoxides (prostaglandins G2 and/or H2) were found both in the perfusate of guinea pig lung (1–3 ng/ml) and in the medium collected after platelet aggregation (13–37 ng/ml). The contractile response of the isolated rabbit aorta to the pure prostaglandins G2 and H2, was also determined. These data combined with the quantitative analyses of the endoperoxides released from the lungs and platelets showed that only a minor part of the rabbit aorta contracting activity was due to the prostaglandin endoperoxides. The major part of the activity consisted of very unstable material. The half life of this material was about 30 s at 37d̀ whereas at this temperature the prostaglandin endoperoxides had a half life of about 5 min.
Consequences of Myocardial Structural Adaptation on Left Ventricular Compliance and the Frank‐Starling Relationship in Spontaneously Hypertensive Rats
Authors: Hallbäck Margareta , Isaksson Olle , Noresson Eddy 
Published: December 2008

AbstractThe Frank‐Starling relationship of hearts from adult spontaneously hypertensive rats (SHR, Okamoto 1969), representing the established phase of hypertension, and of young SHR, representing the initial phase of hypertension, was investigated by using the isoloated working heart preparation. In the “normal” diastolic pressure range (5 to 10 cm H2O), the left ventricle of both SHR groups displayed significantly reduced stroke volumes compared with hearts of normotensive controls (NCR); the degree of reduction being proportional to the left ventricular hypertophy. This is suggested to be due to a reduced left ventricular diastolic compliance in SHR, as indicated by direct measurements of ventricular wall thickness and end‐diastolic volumes in arrested hearts exposed to different end‐diastolic filling pressures. Such a progressive shift of the Frank‐Starling relationship to the right with duration of hypertension could, in combination with the gradual development of “Structural autoregulation” of the precapillary resistance vessels, constitute dominating factors in shifting the hemodynamic situation in labile hypetension into that characterizing the established, or “fixed”, State of hypertension.
Effect of Temperature on Optical Density of Rabbit Blood in Dye Dilution Studies
Authors: M.Anderson Naomi , Creasy Robert K. , de Swiet Michael , Kahanpää Kari V. 
Published: December 2008

AbstractThe optical density of rabbit blood increased on cooling. This increase was additive to the deflection produced by indocyanine green at all concentrations measured. If calibration curves were not corrected for any increasy in optical density produced by cooling the blood, an error (minimum 11%) was introduced in the estimation of cardiac output. The effect of temperature was investigated with three different densitometers. Its wave‐length dependence did not follow the absorption spectrum of oxyhemoglobin.
The Effeect of Restricted Convection‐Diffusion on Bolus Concentration along an Exchange Vessel
Authors: ÅBerg Bo 
Published: December 2008

AbstractIf a sudden rise in solute concentration travels through a capillary system, a diffusible neutral solute passes the walls of the exchange vessels. If then the rate of passage depends on a chemical potential gradient (diffusion) and a hydrodynamical potential gradient (diffusion) and a hydrodynamical potential gradient (convection) and is sterically restricted (restricted convection‐diffusion), water and low molecular weight solvents leave the filtering part of the capillary at a higher rate than the solute, causing a relative increase in its concentration. This phenomenon and the effect of an increasing pore size along the capillary is investigated in a model for an impermeable solute and two diffusible solutes, corresponding to glucose and raffinose. It is shown that in the model, the concentration fall along the capillary tends to become rectilinear.
Enzyme Activities and Muscle Strength after “Sprint Training” in Man
Authors: Thorstensson A. , Sjödin B. , Karlsson J. 
Published: December 2008

AbstractSprint type strength training was performed 3–4 times a week for 8 healthy male students (16–18 yrs). The training was carried out on a treadmill at high speed and with high inclination. Muscle biopsies were obtained from vastus lateralis before and after the training period for histochemical classification of slow and fast twitch muscle fibres and for biochemical determination of metabolites and enzyme activities. Muscle fibre type distribution was unchanged. whereas fibre area indicated an increase for both fibre types in 3 subjects after training. The muscle enzyme activities of Mg2+ stimulated ATPase, myokinase and creatine phosphokinase increased 30, 20, and 36 percent, pespectively. Muscle concentration of ATP and creatine phosphate (CP) did not change with training. Sargent's jump increased with on average 4 cm (from 47 to 51 cm), maximal voluntary contraction (MVC) with 19 kp (from 165 to 184 kp), andurance at 50 percent of MVC with 9 s (from 47 to 56 s), respectively. After training all subjects showed a gain in body weight (mean 1.4 kg) and in thigh circumference (mean 1.5 cm) indicating a larger leg muscle volume and consequently also an increase in total ATP and CP.
Reduction of the Tone of the Isolated Human Umbilical Artery by Indomethacin, Eicosa‐5, 8, 11, 14‐Tetraynoic Acid and Polyphloretin Phosphate
Authors: Strandberg Kjell , Tuvemo Torsten 
Published: December 2008

AbstractThe effects of 2 prostaglandin synthetase inhibitors, indomethacin and eicoa‐5, 8, 11, 14‐terraynoic acid (ETA) and of the prostaglandin antagonist, polyphloretin phosphate (PPP), on the tone of the isolated human umbilical artery and on the responses of this preparation to 5‐hydroxytryptamine (5‐HT) and prostaglandin F2α (PGF2α) were investigated. Indomethacin (8μg/ml), ETA (5 μg/ml) or PPP (40 μ/ml) reduced the tone of human umbilical arteries but had no influence on the responses to 5‐HT. In these concentrations ETA and PPP but not indomethacin antagonized the action of PGF2α. When the concentration of indomethacin or PPP was increased 5‐fold both 5‐HT‐ and PGF2α‐induced contractios were antagonized indicating a non‐specific inhibition at these concentration levels. A 10‐fold increase in the concentration of ETA had no antagonizing action on 5‐HT‐induced contractions suggesting a more selective inhibition of the PGF2α action than displayed by the other compounds. The effects on the tone of the human umbilical artery of the compounds studied might reflect inhibition of prostaglandin biosynthesis and/or antagonism of prostaglandins contributes to the maintenance of tone of the isolated human umbilical artery.
Effects on Gastric Motility from the Cerebellar Fastigial Nucleus
Authors: Lisander Björn , Martner Jan 
Published: December 2008

AbstractIn acute experiments on chloralosed cats gastric motility, blood pressure and heart rate were investigated for influences exerted by the fastigial nucleus. Besides pressor responses, fastigial stimulation could produce either gastric excitation or relaxation and the background of these responses was analysed by selective nerve sectioning and administration of suitable autonomic blocking agents. Suppression of prevailing gastric motility was found to be mediated mainly by increased discharge in adrenergic nerve fibres but also by adrenal catecholamine release.–Gastric excitation could be induced in three different ways, first via increased activity in vagal cholinergic fibres, second, by fastigial suppression of the vago‐vagal non‐adrenergic relaxatory reflex. In addition, when laparotomy or other noxious abdominal stimuli had induced inhibitory gastric reflexes, the consequent sympathetic discharge could be suppressed by fastigial stimulation resulting in enhanced gastric motility.–The importance of background activity in the various nervous pathways for the fastigially induced gastric responses is discussed.
The Capillary Permeability of the rete mirabile of the Eel, Anguilla vulgaris L.
Authors: Stray‐Pedersen Sverre , Steen Johan B. 
Published: December 2008

AbstractDirect measurements of transcapillary exchange during steady‐state conditions have been performed in the rete mirabile of the eel. The capillaries were found to be more than 30 times as permeable to THO (PTHO= 33.2 × 10‐5 cm sec‐1), ethanol and antipyrine than to K+. The mutual relationship of the permeabilities for K+, Na+, urea and sucrose were similar to that between the corresponding free diffusion coefficients in water. The permeability characteristics did not change when the perfusate contained metabolic inhibitors. Addition of 1 mM/1 of albumin lead to a significant transcapillary osmotic flow. NaCl, urea and sucrose, however, did not cause osmotic flow. Based on the quantitative values for permeability and volume flow the capillary pores should be about 1300 Å and have a frequency of 1.3 × 106 per cm2 of the capillary surface, occupying an area of about 0.1% of the total area. The results obtained in the present investigation raise questions as to the validity of the Pappenheimer single‐pore theory for transcapillary transport as well as to the fine structure of the capillary pores. As an alternative to Pappen‐heimer's theory a multi‐pathway model is proposed in order to explain transcapillary transport.
Synthesis of Catecholamines in the Eye after Local Injection of3H‐Precursors
Authors: Rentzhog Leif 
Published: December 2008

AbstractThe possibility that adrenaline may be synthesized locally in the eye was investigated in the rabbit and vervet monkey. L‐tyrosine‐3,5‐3H, L‐tyrosine (side‐chain‐2,3‐3H) or L‐3,4–dihydroxyphenylalanine (3H(G)) was injected into the anterior chamber or the vitreous. The animals were killed after 1/2 h up to 7 days in the tyrosine experiments and after 1 up to 24 h in the DOPA experiments. The synthesis of3H‐adrenaline,3H‐noradrenaline and3H‐dopamine was measured with a modified version of a double isotope technique for determination of catecholamines. No3H‐adrenaline was found. An attempt to stimulate the phenylethanolamine‐N‐methyltransferase activity with a glucocorticoid and to inhibit the metabolism of catecholamines with a monoaminoxidase inhibitor also failed to demonstrate3H‐adrenaline synthesis.3H‐noradrenaline was found in all experiments when3H‐DOPA had been given. The amounts were about 10 times higher after injection into the anterior chamber than after injection into the vitreous.3H‐dopamine was found in all except a few experiments after3H‐DOPA injection. The highest amounts were found after injection into the vitreous. In experiments with3H‐tyrosine we were unable to demonstrate any catecholamine synthesis. This prompts the question of whether tyrosine‐hydroxylase may be absent in the eves of certain animal species.
Renal Handling of Human β2‐Microglobulin in the Rat: The Importance of Sham‐Operation
Authors: Ravnskov Uffe , Karátson András 
Published: December 2008

AbstractThe plasma disappearance rates of human β2‐microglobulin and (hydroxy‐methyl‐C14)‐inulin was measured in unoperated, sham‐operated, ureter‐ligated and nephrectomised rats. Judging from the C14–activity curves in ureter‐ligated and nephrectomised rats a substantial glomerular filtration continued after obstruction of the urine flow. Almost 90% of the injected protein had disappeared from plasma 120 min after injection into nephrectomised rats indicating a considerable extra‐renal elimination and invalidating attempts to evaluate different renal mechanisms of elimination before and after ureter‐ligation. Sham‐operation induced an increase of the plasma disappearance of both β2‐microglobulin and inulin. The latter phenomenon may explain earlier findings of similarity between the disappearance curves of low molecular weight proteins in unoperated and ureter‐ligated animals and stresses the importance of using sham‐operated animals as controls.
Cardiovascular Responses to Changes in Carotid Sinus Transmural Pressure in Man
Authors: Bjurstedt H. , Rosenhamer G. , Tydén G. 
Published: December 2008

AbstractTo study the relative importance of cardiac and peripheral effector mechanisms in the carotid sinus baroreflex in man cardiovascular responses to equal changes of the carotid sinus transmural pressure (Ptm) in either direction of the normal were recorded and compared in eight physically well‐trained young male volunteers. In both the supine and the 70d̀ head‐up position, a decrease in Ptm produced a more potent reflex response of the systemic arterial pressure than did a similar increase in Ptm. Whereas the arterial pressure response to increased Ptm was due solely to a reduction in vascular resistance, a significant increase in cardiac output contributed to the more potent pressor response to a decrease in Ptm and thus to the predominantly antihypotensive properties that characterize the carotid sinus baroreceptor control system in man. However, since combined beta‐adrenergic and parasympathetic blockade abolished the effect of reduced Ptm on cardiac output without greatly impairing the blood pressure response, it is concluded that adjustments in cardiac output are not of critical importance in the buffering function of the carotid sinus baroreceptors. Autonomic cardiac blockade exaggerated the fall in cardiac output on head‐up tilt, the arterial pressure remaining unaffected due to a compensatory increase in systemic vascular resistance.
Effect of Cold Exposure on Free Water Reabsorption in Hydropenic Man
Authors: Wallenberg L. R. 
Published: December 2008

AbstractWith clearance technique, changes in tubular reabsorption of solute free water(TH2Oc), were studied in a group of 9 healthy hydropenic volunteers during a cold stress of 1 h at + 15°C.Increases were found in(TcH20)and in fractional excretion of sodium and osmoles during cold.Since(TCH2O)was used as an index of sodium reabsorption in the ascending limb of Henle's loop, the findings indicated that under the conditions used in this study, the concentrating ability of the kidney was not negatively influenced by cold, despite a significant increase in arterial pressure.It is suggested that the reabsorption by the ascending limb of the loop was increased secondary to a reduced proximal tubular reabsorption of sodium.
Differential Effects of Temperature on Activity of LDH from Seal and Sheep Skin
Authors: Blix Arnoldus Schytte , Messelt Edvard B. , Grav Hans J. 
Published: December 2008

AbstractThe homeothermic seal possesses a heterothermic skin, while the skin of the sheep behaves as a truly homeothermic tissue. A new method for skin homogenization is described. The effect of temperature on the catalytic behaviour of seal and sheep skin LDH has been investigated by fluorimetric activity measurements, with results presented as Arrhenius plots. The seal skin enzyme had ten times higher activity at low temperatures as compared to the sheep skin. The mechanisms responsible for this different behaviour are discussed.
Effect of Spinal Sympathetic Blockade upon Local Regulation of Blood Flow in Subcutaneous Tissue
Authors: Henriksen O. , Alsner T. 
Published: December 2008

AbstractThe influence of spinal sympathetic blockade upon local regulation of blood flow in subcutaneous adipose tissue was investigated in six subjects. The effect of changes in orthostatic pressure on blood flow in subcutaneous tissue in the crus and distal forearm was measured before and after sympathetic blockade obtained by epidural anesthesia in 4 subjects and by a bilateral sympathectomy in 2 patients suffering from manual hyperhidrosis. Blood flow in subcutaneous tissue measured by133Xe washout technique decreased by about 40 per cent when the limb was lowered, and remained constant during 30 cm elevation. This was found both before and after the blockade, though in one of the patients, the orthostatic decrease in blood flow was less pronounced 24 h after sympathectomy. Hence central sympathetic reflexes do not alter local orthostatic changes of blood flow in subcutaneous tissue. These changes therefore are most likely due to local mechanisms.
Recovery of ADH Activity in the Urine of Goats under Normal and Stimulated Conditions
Authors: Lishajko F. , Anderson B. 
Published: December 2008

AbstractThe hydrated goat was used for bioassays of, antidiuretic hormone (ADH) activity recovered by resin column separation from the urine of other animals of the same species. A methodological innovation in the separation procedure was ethanol purification of the column before elution. In this manner substances which sometimes obscured the bioassays were eliminated without loss of ADH activity. With the bioassay method employed, it was possible to determine to the nearest 0.5 of a mU the ADH activity of unknown samples, provided they contained between 0–5 mU of ADH. When arginine vasopressin was infused intravenously into hydrated animals, slightly more than 10% of its antidiuretic activity was recovered in the urine. In the water replete goat the ADH activity found in the urine was of the order of 1 mU per hr urine secretion, indicating a neurohypophyseal ADH release of approximately 5 μU/kg min. After 48 h of dehydration in an environmental temperature of 20°C the renal ADH excretion increased to about 8 mU/h, suggesting an 8‐fold increase of ADH secretion over basic, water replete secretion of ADH. ADH secretion of the same high order was induced in hydrated animals by the infusion of angiotensin II together with hypertonic NaCl into the lateral cerebral ventricle.
Imitation of Glucagon Effects on Splanchnic Hemodynamics and Liver Function by N6, 2′‐O‐Dibutyryl 3′,5′‐Cyclic AMP (DBcAMP) in Cats
Authors: Krarup Niels , Larsen Anker Jens , Munck Anders 
Published: December 2008

AbstractFasting cats anesthetized with chloralose were used for the experiments. DBcAMP infused at a rate of 340 nmol/kg/min increased the gastrointestinal and intrahepatic portal conductances whereas the hepatic arterial conductance was decreased. The hemodynamic responses to portal and systemic venous administration of DBcAMP were identical. In half of the experiments DBcAMP increased the splanchnic ethanol elimination rate and oxygen consumption and in all experiments there was a decrease in the plasma clearance and extraction ratio of Indocyanine Green. No change in bile flow was observed. DBcAMP infused at a rate of 85 nmol/kg/min was without significant effects on either splanchnic hemodynamics or liver metabolism. DBcAMP infused at a rate of 850 nmol/kg/min accentuated the decrease in hepatic arterial conductance but was found to decrease the splanchnic ethanol elimination rate and oxygen consumption. Infusion of cAMP, AMP and adenosine at a rate of 340 nmol/kg/min were without measurable effects. Based on these results it is concluded that like the metabolic effects also the vascular effects of glucagon are caused by stimulation of specific glucagon receptors which results in an intracellular release of cAMP.