bluuebunny/crossref_metadata_2025 huggingface dataset:
Differences in Secretory Excitability between Short and Long Adrenergic Neurons: Comparison of 3H‐Noradrenaline Secretion Evoked by Field Stimulation of Guinea‐Pig Vas Deferens and Human Blood Vessels
Authors: Stjärne Lennart
Published: December 2008

On comparing the secretion of noradrenaline (NA) evoked by electrical field stimulation of the ‘short’ adrenergic nerves of guinea‐pig isolated vas deferens (Sjöstrand 1962) with that evoked by similar stimulation of the ‘long’ adrenergic nerves of human isolated omental blood vessels, using identical experimental conditions, it was found that the two types of nerve differ markedly in ‘secretory excitability’. While it was possible to adjust the strength and/or duration of stimulus shocks to a level causing a well‐defined maximum in 3H‐NA output from the human vasomotor nerves, no such ‘supramaximal’ level could be reached in the nerves of guinea‐pig vas deferens.
Structural “Resetting” of the Renal Vascular Bed in Spontaneously Hypertensive Rats (SHR)
Authors: Folkow B. , Göthberg G. , Lundin S. , Ricksten S.‐E.
Published: December 2008

Studies in both man and rats (cf. Folkow et al. 1973, 1974) show that a rapid structural adaptation occurs early in hypertension which, besides the left heart and systemic arteries, affects the precapillary resistance vessels in a hemodynamically most important way. Here a wall (mainly media) thickening takes place which tends to encroach upon the inner radius, thus raising the w/ri ratio. The rapidity, generalization and extent of this precapillary ‘“structural autoregulation” to average changes in pressure load makes it crucial both for the initiation and maintenance of a chronic high‐pressure state, whichever the initiating elements are. The same principle of hypertrophic adaptation in the left heart and large arteries leads to a functionally important displacement of the “Starling curve” towards the right (Hallbäck, Isaksson and Noresson 1975) and to baroreceptor resetting (e.g. Jones 1977).
Cerebral Blood Flow and Oxygen Consumption in Rat, Measured with Microspheres or Xenon
Authors: Gjedde Albert , Monte S. M. De La , Caronna John J.
Published: December 2008

The cerebral blood flow and, in some rats, the cerebral rate of oxygen consumption were measured in three groups of male rats. Fractionation of radioisotope‐labeled microspheres was used to measure regional cerebral blood flow in four parts of the rat brain. The arterial and cerebral venous concentrations of radioactive xenon during desaturation were used to measure the blood flow and oxygen consumption of cortex when venous blood was collected from the superior sagittal sinus, or of whole brain when the transverse sinus was sampled. The regional cerebral blood flow measured with microspheres had a large standard error reflecting the technical difficulty of this method. The cerebral blood flow measured with xenon was higher when venous blood was sampled from the superior sagittal sinus than when sampled from the transverse sinus, but cerebral oxygen consumption rates were similar. The difference reflects the greater trauma involved in the superior sagittal approach and possible extracerebral contamination present in the transverse sinus approach.
Adenylate Cyclase Activity in Corpus Striatum of Rats with Porto‐Caval Anastomosis
Authors: Laursen H. , Klysner R. , Geisler A.
Published: December 2008

Altered catecholamine receptor sites within the striatum have been proposed to be an important pathogenetic factor in hepatic and porto‐systemic encephalopathy and coma. The unstimulated, fluoride‐, norepinephrine‐ and dopamine‐stimulated adenylate cyclase activity were measured in the corpus striatum of rats with a four weeks old end‐to‐side porto‐caval anastomosis. There was no difference in unstimulated, fluoride‐ or hormone‐stimulated adenylate cyclase activity between porto‐caval shunted and sham‐operated rats. The in vitro dose‐response curves of norepinephrine and dopamine were similar in both groups of animals. Half‐maximum and maximum stimulation were achieved in shunted and sham‐operated rats by identical concentrations of norepinephrine and dopamine, respectively. The results indicate that neither changes in unstimulated adenylate cyclase activity nor changes in the response of adenylate cyclase activity to fluoride, norepinephrine and dopamine had developed in the rats at the stage studied.
Central and Regional Circulatory Effects of Adding Arm Exercise to Leg Exercise
Authors: Secher Niels H. , Clausen Jan P. , Klausen Klaus , Noer Ivan , Trap‐Jensen Jens
Published: December 2008

7 young, healthy, male subjects performed exercise on bicycle ergometers in two 20 min periods with an interval of 1 h. The first 10 min of each 20 min period consisted of arm exercise (38–62% of Vdot;o2max for arm exercise) or leg exercise (58–78% of Vdot;o2max for leg exercise). During the last 10 min the subjects performed combined arm and leg exercise (71–83% of Vdot;o2max for this type of exercise). The following variables were measured during each type of exercise: oxygen uptake, heart rate, mean arterial blood pressure, cardiac output, leg blood flow (only during leg exercise and combined exercise), arterio‐venous concentration differences for O2and lactate at the levels of the axillary and the external iliac vessels.

Superimposing a sufficiently strenuous arm exercise (oxygen uptake for arm exercise 40% of oxygen uptake for combined exercise) on leg exercise caused a reduction in blood flow and oxygen uptake in the exercising legs with unchanged mean arterial blood pressure. Superimposing leg exercise on arm exercise caused a decrease in mean arterial blood pressure and an increased axillary arterio‐venous oxygen difference. These findings indicate that the oxygen supply to one large group of exercising muscles may be limited by vasoconstriction or by a fall in arterial pressure, when another large group of muscles is exercising simultaneously.
On the Cation Exchanger Properties of Rat Mast Cell Granules and their Storage of Histamine
Authors: Uvnäs Börje , ÅBorg Carl‐Hugo
Published: December 2008

Mast cell granules free of a surrounding membrane were isolated from water‐lysed rat peritoneal and thoracic mast cells by differential centrifugation. The granules were depleted of their histamine by suspension in 10 mM sodium phosphate buffer and the sodium‐charged granules then converted into the “hydrogen form” by repeated washing in slightly acid deionized water. The cation exchanger properties of the mast cell granules were investigated by testing the applicability of the Rothmund‐Kornfeld equation for cation exchangers to the binding of Na+ and Hi+ ions to granule sites. The results lend further support to the view that the mast cell granule acts as a cation exchanger with the exchanger function localized to protein carboxyls in the protein‐heparin complex of the granule matrix.
Early Oestrogen‐Induced Changes in Uterine Albumin Exchange in Mice
Authors: Arvidson N. G.
Published: December 2008

The effect of the oestrogens, oestradiol and oestriol, on plasma albumin dynamics in the uterus was studied in mice. A double isotope technique with125I‐ and131I‐labelled human serum albumin was used. The optimum conditions to measure the extravascular accumulation of albumin were to use one labelled albumin as “permeability marker” (30 min circulation time) the other as plasma volume indicator (3 min circulation time). The oestrogens increased the extravascular accumulation of labelled albumin in the uterus but not in diaphragm or heart muscle. The accumulation was maximal after 4 h (75% higher than in controls) and was significant as early as 2 h after oestrogen administration. It cannot be decided whether the increase in labelled albumin accumulation was due to an increase in permeability and/or to an increase in the total surface area of perfused capillaries.
Oxygen Consumption and Contractile Force during Vibrations of Cat Soleus Muscle
Authors: Ljung Bengt , Hallbäck Margareta , Sivertsson Ramon , Folkow Björn
Published: December 2008

The influence of longitudinal vibrations (50 Hz, 0.4 mm) on isometric twitch force development (4 Hz), blood flow and oxygen consumption was studied in the acutely denervated soleus muscle of the anesthetized cat. It was found that the sinusoidal vibrations reduced the twitch amplitude by 60 per cent whereas oxygen consumption and blood flow were lowered by 15 per cent only. Similar reduction in twitch force was also obtained by lowering the nerve stimulation intensity (4 Hz). This was associated with a diminution in oxygen consumption, the degree of which was linearly related to the attenuation of active force, i.e. the number of activated motor units. The results are in agreement with previous observations as to the mechanical effect of vibrations on active force in smooth and striated muscle. They demonstrate that vibrations prevent the contractile response with maintained high oxygen consumption which adds further support to the hypothesis forwarded by Joyce et at. (1969) that vibrations cause increased rate of detachment of actin‐myosin crosslinks. In addition it appears possible that vibrations to some extent prevent formation of such cross‐links.
Transcapillary Exchange of14C‐Inulin by Free Diffusion in Channels of Fused Vesicles
Authors: Paaske William P. , Sejrsen Per
Published: December 2008

Capillary permeability for the extracellular, hydrophilic indicator,14C‐inulin, was determined in the autoperfused cat gastrocnemius muscle by bolus injection, venous sampling expts. The capillary diffusion capacity, CDC (the permeability‐surface are product, PS), was 0.84 ml/100 g·min, and capillary extraction, E, was 0.307 at a plasma flow of 4.0 ml/100 g·min as average values of 7 expts. Results were compared with51Cr‐EDTA and57Co‐B12 data of previous studies. The findings imply that14C‐inulin is not subject to restricted diffusion across the continuous capillary membranes of skeletal muscle as compared to51Cr‐EDTA as well as57Co‐B12. These hydrophilic indicators pass the capillary barrier at rates proportional to their respective free diffusion coefficients in water. The Pappenheimer equivalent pore radius estimate of 30 Å (or slit width of 37 Å) and the Karnovsky 40 Å interendothelial slit width are inconsistent with the present data which imply a much larger pore size. The transendothelial channel system of fused vesicles is a possible morphological equivalent for the present findings which support the general theory that capillaries of continuous type exhibit similar permeation characteristics regardless of the tissue in which they are located. By kinetic black‐box analysis the extravascular distribution volume for14C‐inulin in skeletal muscle was found to be 13.0 ml/100 g. The data indicate that51Cr‐EDTA, which has about the same molecular radius as sucrose, and14C‐inulin have identical extravascular volumes of distribution and that both molecules presumably enter the sarcoplasmic reticulum.
A Simple Radioenzymatic Procedure for the Determination of Choline and Acetylcholine in Brain Regions of Rats Sacrificed by Microwave Irradiation
Authors: Eckernäs S.‐Ä. , Aquilonius S.‐M.
Published: December 2008

A rapid and sensitive radioenzymatic method for analysis of choline (Ch) and acetylcholine (ACh) concentrations in rat brain regions is described. The ACh content is obtained as the difference in Ch concentration between a hydrolysed and an unhydrolysed tissue sample. The ACh content was 16 ± 1.0 nmol/g in the cortex and 76 ± 2.4 nmol/g in the striatum, and the corresponding Ch values were 23 ± 2.5 and 33 ± 1.2.
Monoaminergic Fluorescence in Frog Skin
Authors: Sjöberg Eva
Published: December 2008

The Falck‐Hillarp fluorescence technique was employed in an attempt to determine the distribution of sympathetic innervation in frog skin. No evidence was found of a direct monoaminergic nerve supply to the cells of the non‐glandular epithelium in the epidermis. Instead, specific fluorescence was mainly confined to the vicinity of the skin glands. Fluorescent fibers were observed surrounding the mucous type of gland. The secretory content of this gland was not fluorescent. In the granular type of gland the main source of fluorescence was the secretory granules filling the lumen. These developed a fluorescence in the spectral range of 5‐hydroxytryptamine. The brightness of the fluorescence indicated a very high content of this amine. Fluorimetric analysis showed that no catecholamines were present in the secretion. In glands devoid of secretory granules there were some indications of a monoaminergic innervation of the secretory epithelium, but this was hard to determine because of the abundant nonspecific fluorescence. Sparse dots of specific fluorescence were found close to the surrounding smooth muscle cells. — These findings rule out the possibility of a direct sympathetic nervous control of the non‐glandular epithelium in frog skin but indicate that this is instead confined to the skin glands.
In Vivo Studies of Individual Mucous Glands in the Frog
Authors: Skoglund C. R. , Sjöberg E.
Published: December 2008

Individual mucous glands in the toe web were studied in curarized decerebrate frogs using vital microscopy in combination with still or motion photomicrography. By changing the focus position to different levels various structures in the gland could be identified and their changes during glandular activation studied. The first visible effect of nerve stimulation was a contraction of the myoepithelium and probably also structural changes of the secretory epithelium resulting in a narrowing of the glandular lumen. Following this, the tricuspid valve opened and secretion was ejected. The latency and time course of the contractile response to nerve stimulation were determined and the influence of the number of stimuli on the duration of the contraction and relaxation phases was analyzed. Comparisons were made with reflex activation of the gland as well as with neurohormonal stimulation. The myoepithelial contraction was found to be under adrenergic control. Of the smooth‐muscle stimulants tested only Substance P induced contractions. The time course of the ionic outflow from the toe web was determined by conductance measurements in the fluid surrounding the web and compared with the visually observed phenomena. The initial outflow was concomitant with the phasic myoepithelial contraction but a continued secretion could also be observed and recorded from glands kept in a steady state of contraction by iterative nerve stimulation. The functions of the toe web glands were found to be critically dependent on a maintained circulation in the surrounding capillary network.
The Effect of Indomethacin on Renal Blood Flow Distribution during Hemorrhagic Hypotension in Dog
Authors: Tyssebotn I. , Kirkebø A.
Published: December 2008

The effect of indomethacin in hemorrhagic hypotension (HH) on total renal blood flow (RBF) and cortical flow distribution was studied in 9 pentobarbital anesthesized dogs. Local blood flow was measured as hydrogen clearance by 6 platinum electrodes in outer and inner cortex. RBF was recorded by electromagnetic flowmeter. Injection of indomethacin (3–5 mg/kg b.wt.) to inhibit prostaglandin synthesis, reduced renal blood flow only a few percent in control period. After the pretreatment with indomethacin, bleeding to mean arterial pressure 50 mmHg decreased RBF abruptly to 25% of control flow. Thus a renal vasoconstriction is observed both in early and late periods of bleeding in contrast to the initial vasodilation observed during the first half an hour of HH when prostaglandin formation was not blocked. Local blood flow in outer cortex decreased proportionally to flow in inner cortex during bleeding in both the indomethacin treated as in the untreated group, indicating an equal vasodilatory effect of prostaglandin in all parts of renal cortex during early periods of HH.
Effects of Ethanol on Urinary Arginine Vasopressin Excretion in Two Rat Strains Selected for Their Different Ethanol Preferences
Authors: Linkola Jaakko , Fyhrquist Frej , Forsander Olof
Published: December 2008

The effects of ethanol on urinary excretion of arginine vasopressin (AVP), sodium, and potassium were investigated in two rat strains specially selected for their different alcohol preferences. The alcohol preferring (AA) strain excreted more AVP and the water preferring (ANA) strain more urine and sodium during six hours after ethanol intubation (2.4 g/kg b.w.; 20% v/v). The data is insufficient to establish a causal relationship between differences in water and electrolyte metabolism and voluntary ethanol consumption.
The Interrelation between Hypothalamically Induced Changes in Sympathetic Discharge to the Gastrointestinal and Cardiovascular Systems
Authors: Delbro Dick , Lisander Björn
Published: December 2008

In chloralose‐anesthetized, adrenalectomized cats, the sympathetically conveyed effects of topical hypothalamic stimulations on gastric volume, blood pressure and heart rate were systematically explored. The vagal nerves were cut but could be kept active by graded efferent stimulation. In the absence of such vagal activity, hypothalamic stimulation had no appreciable influence on gastric volume, even though the stomach maintained considerable myogenic tone. When, however, a vagal excitatory activity was present, hypothalamic stimulation could markedly affect gastric tone, indicating that the sympathetic fibres exert their inhibitory influence on the stomach via its cholinergic intramural neurons. Hypothalamic stimulations that induced reductions in pressure or heart rate also usually caused an enhancement of gastric tone. Similarly, pressor responses were associated with decreases in gastric volume whereas stimulation‐induced tachycardia was not linked to any particular type of gastric response. Thus, the hypothalamic sympathoinhibitory influences on the cardiovascular system seem closely connected to a suppression of the sympathetic outflow to the stomach. There is, on the other hand, no regular association between hypothalamic sympatho‐excitatory influences on the cardiovascular and gastrointestinal systems; in fact, there is in many areas even a suppression of sympathetic discharge to the stomach in association with cardiovascular stimulation.
Fever and Behavioural Temperature Regulation in the FrogRana esculenta
Authors: Myhre Kjell , Cabanac Michel , Myhre Grete
Published: December 2008

The skin and colonic temperatures were recorded in frogs(Rana esculenta)which had selected a suitable microenvironment in a box filled with 2–3 cm water. The water temperatures ranged from 0°C to + 40°C. Such measurements were performed before and after intraperitoneal injections of killed pathogenic bacteria (M. xenopiandM. ranae), killed non‐pathogenic bacteria (M. aquae II) and 0.9% sterile saline, intraperitoneal injections of blood plasma from frogs pre‐injected with killedM. ranae, injections of PGE, into the brain. The injections of pathogenic bacterial endotoxin caused, after latencies of 5–120 min, higher preferred water temperatures, which produced an average maximum colonic temperature increase of 6.5°C ± 1.0°C (S.E.) (p< 0.001). The non‐pathogenic bacteria and sterile saline caused no temperature change. Monophasic hyperthermia of shorter latency was caused by injections of blood plasma from frogs pre‐injected withM. ranae.Monophasic hyperthermia of the shortest latency was observed after diencephalic injections of PGE1. Based on their similarity we suggest that ectothermic and endothermic fever have a common phylogenetic origin.
Postischemic Cerebral Blood Flow and Oxygen Utilization Rate in Rats Anesthetized with Nitrous Oxide or Phenobarbital
Authors: Nordström Carl‐Henrik , Rehncrona Stig
Published: December 2008

The present experiments were undertaken to measure postischemic regional cerebral blood flow (rCBF) and oxygen utilization rate (CMRo2) in rats anesthetized with either 70 % N2O or phenobarbital (150 mg × kg‐1). In previous studies we have found that extensive restitution of cerebral energy metabolites occurs after 30 min of complete cerebral ischemia irrespective of the type of anesthesia used. Following 30 min of pronounced, incomplete ischemia, however, a comparable restitution of cerebral energy state was obtained in deeply anesthetized (phenobarbital 150 mg × kg‐1) but not in superficially anesthetized (70% N2O) rats. The objectives of the present investigation were (1) to study whether postischemic cerebral blood flow was higher in barbiturate‐anesthetized animals during the initial recirculation period, and (2) to investigate if the protective effects of phenobarbital previously observed could be attributed to a decrease in CMRo2. In both groups of animals a considerable variability in postischemic rCBF was observed between different animals. However, no signs of gross inhomogeneity in blood flow were found and no consistent differences in flow values between the two groups of animals were observed. Since the measured postischemic CMRo, were identical in both groups of animals and since cerebral venous oxygen contents were above normal the results leave little support to the assumption that, in the present model of transient, incomplete cerebral ischemia, failure of recovery of cerebral metabolism (N2O group) is primarily due to impaired recirculation, nor do they indicate that the protective effects of barbiturates is due to their ability to reduce rate of cerebral energy utilization.
Protein Concentration in Interstitial and Lymphatic Fluids from the Subcutaneous Tissue
Authors: Rutili Gianfranco , Arfors Karl‐E.
Published: December 2008

The protein content of interstitial fluid and lymph from the same tissue was determined, fluid samples of nanolitre volumes being taken from the subcutaneous tissue of rabbits by micropuncture. In the same area lymph was collected from lymphatic vessels of 30–100 μm. An electrophoretic technique in poly‐acrylamide gels in glass capillaries was used for the analysis of proteins. The gels were stained and then scanned on a microscope equipped with a moving table and photomultiplier. The area under each protein band was calculated from the recorded densitograms. The method required only a few nanolitres of fluid for analysis. Using solutions of known protein concentrations the relationship between the amount of protein and the area under the densitogram band was investigated. This relationship was found to be linear, making it possible to quantify the protein content of both interstitial fluid and lymph samples. The interstitial fluid/plasma concentration ratios for albumin, transferrin, globulins and total proteins were 0.42, 0.42, 0.32 and 0.37. The albumin/globulin ratio in interstitial fluid was found to be 1.60 of the plasma value although the values obtained for lymph were similar to those found for interstitial fluid. The similarity between the protein concentration of interstitial fluid and lymph indicated that the endothelial lining of the terminal lymphatics did not restrict the passage of macromolecules into the lymphatics.
Pineal Serotonin Metabolism in Non‐Innervated Perinatal Glands before and after Intraocular Maturation: Supersensitivity of Adrenoceptors that have never been Innervated
Authors: Bäckström Maria , Olson Lars , Seiger ÅKe
Published: December 2008

Transplantations were made of fetal pineal glands (crown‐rump length, CRL, 19–30 mm) or pineal glands from adult male rats to the anterior chamber of the eye of the rat. Studies were performed with regard to the importance of the age of the donor animal (and thereby the degree of maturation and innervation of the gland to be transplanted) for the possible development of denervation supersensitivity. The transplants were cultured in a medium containing14C‐serotonin. Increased production of14C‐N‐acetylserotonin (NAcS) was used as the main criterion for β‐adrenergic stimulation. 4 experimental groups were obtained by transplanting fetal or adult pineals to intact or sympathetically denervated eyes. In all 4 groups β1‐stimulation (KWD 2033 10‐6M) increased14C‐NAcS formation. The response to β‐stimulation was significantly higher in denervated fetal pineal transplants than in innervated fetal transplants and thus demonstrating β‐receptor supersensitivity. It was concluded that a) the ability to respond to β‐adrenoceptor stimulation with increased14C‐NAcS formation develops between the 18th and 20th day of gestation, b) transplants derived from fetal as well as from adult rats can respond to β‐adrenergic stimulation, c) this sensitivity also developsin oculoin transplants that at the time of transplantation lacked the capacity to increase their14C‐NAcS formation in response to treatment with β‐agonist, d) denervation supersensitivity occurs in fetal transplants that became mature in sympathetically denervated eyes.
Preferential Uptake of 14C‐α‐Aminoisobuturic Acid into Mouse Uterine Tissue during Early Pregnancy
Authors: Lindqvist Iinger , Nilsson Ove , Ronquist Gunnar
Published: December 2008

The uptake of 14C‐AIB into uterine tissue and some other organs was studied during early implantation. Mice in experimentally delayed implantation were given estrogen and 14C‐AIB at different time intervals. Mice in delayed implantation given only 14C‐AIB displayed a low transport rate into the uterine tissue, comparable with that for the diaphragm muscle. However, if the estrogen injection preceeded that of the 14C‐AIB by 4 to 8 h the transport capacity increased by a factor of at least 4 times while the uptake for the diaphragm muscle remained low. Under such conditions 14C‐AIB‐accumulation into uterine tissue was favoured for at least 4 h of in vivo incubation with the labeled amino acid.
Regulation of Respiration: “The Black Box”
Authors: Asmussen Erling
Published: December 2008

A close relation between the state of wakefulness, the electroencephalogram, and the respiration has been demonstrated (Bülow 1963). In the present paper it was assumed that as opening and closing of the eyes influence the EEG and thus probably the state of wakefulness, the responsiveness of the respiratory center may likewise be influenced by the single act of closing the eyes. Seven subjects were studied in the steady state of rest breathing ambient air, 4–5 % CO2 in air, or 11 % O2 in nitrogen. In experimental periods of 4–5 minutes their pulmonary ventilation and alveolar Pco2 were measured while they randomly were either reading a book, or were blindfolded. It was found that in all three conditions closing of the eyes resulted in a mean decrease of VE of 8 to 14 % with a concomitant increase of PACO2 of about 1 mmHg. It is tentatively suggested that other and stronger central or peripheral stimuli impinging on the reticular formation of the brain may explain the changed sensitivity of the respiratory center towards the chemical stimuli in conditions like exercise, chronic hypoxia etc.
Time Course of Changes in Human Skeletal Muscle Succinate Dehydrogenase and Cytochrome Oxidase Activities and Maximal Oxygen Uptake with Physical Activity and Inactivity
Authors: Henriksson Jan , Reitman James S.
Published: December 2008

Succinate dehydrogenase (SDH) and cytochrome oxidase activities in the lateral vastus of the human quadriceps femoris muscle together with total body V́o2 max were followed during an 8–10 week period of endurance training (n=13) and a successive 6 week period without training (n = 8). During the training period there was a gradual increase in both Vo. max and muscle oxidative enzyme activities, all being significantly different from the pre‐training levels after 3 weeks of training. After 8 weeks of training V́o2. max was 19%, vastus lateralis SDH 32%, and cytochrome oxidase activity 35% above the pre‐training levels respectively. 6 weeks post‐training V́o3 max was still 16% above the pre‐training level, and not signifi‐ficantly different from the level at the end of training (p >0.2). In contrast vastus lateralis SDH activity had returned to the pre‐training level. Cytochrome oxidase activity had returned to the pre‐training level within two weeks post‐training. The significantly faster post‐training decline in skeletal muscle oxidative enzyme activities in contrast to that of the V́o2 max indicates that an enhancement of the oxidative potential in skeletal muscle is not a necessity for a high V́o2 max. Moreover, the fast return to the pre‐training level of both SDH and cytochrome oxidase activities indicate a high turnover rate of enzymes in the TCA cycle as well as the respiratory chain.
Choline Acetyltransferase Activity in Parotid Glands of Rats after Prolonged Treatment with Pilocarpine
Authors: Ekström Jörgen
Published: December 2008

The enzyme activity, expressed as total activity and concentration, was found to be decreased in the cholinergic neurones of the glands after treatment with pilocarpine for 10 days. The secretion of saliva evoked by the parasympathomimetic drug is thought to have reduced the reflex stimulation of the glands via the cholinergic secretory nerves and thereby lowered the enzyme activity in the nerves.
Twenty‐Four Hour Variation in Flow and Composition of Leg Lymph in Normal Men
Authors: Engeset A. , Olszewski W. , Jæger P. M. , Sokolowski J. , Theodorsen L.
Published: December 2008

The twenty‐four hour variation in concentration and output of total protein, lactate dehydrogenase and alkaline phosphatase has been studied in the peripheral lymph from the legs of 5 healthy volunteers over a period of five days. The highest concentration of these proteins was found in lymph collected during the first two hours after a night's rest. During the day a continuous decrease in concentration occurred without any direct correlation to lymph flow. The variation in lymph protein concentration between early morning and late day was about 40 %, lactate dehydrogenase and alkaline phosphatase about 90% and 45o, respectively.
Time Course and Extent of Carotid Sinus Baroreceptor Threshold Resetting in Rats with Renovascular Hypertension
Authors: Jones John V.
Published: December 2008

To study the extent and time course of arterial baroreceptor threshold resetting to increases in blood pressure, renal hypertension was induced in young normotensive male Wistar rats by unilateral renal artery constriction. At different intervals after operation the extent of baroreceptor threshold resetting in the carotid sinus was examined. Experiments were performed 7, 14 and 25 days after renal artery clipping to enable baroreceptor resetting to be correlated with the rate and extent of cardiovascular changes in rats which had renovascular hypertension of identical durations (Lundgren et al. 1974). Baroreceptor thresholds in the carotid sinuses were established by progressive clamping of both carotid arteries after partial vascular isolation of the sinuses. The results show that after one week of hypertension baroreceptor resetting is only just apparent but by two weeks resetting is gross and seems to be largely completed. This parallels the adaptive changes in the hindquarters of renal hypertensive rats and it is concluded that baroreceptor resetting is a secondary phenomenon related to the structural changes induced in the vessels by the elevated blood pressure.
Conjugated Catechol Derivatives in a Transplantable Islet Cell Tumour of the Golden Hamster
Authors: Falck B. , Hansson C. , Kennedy B.‐M. , Rosengren E.
Published: December 2008

Two glucuronidated catechol derivatives have been identified in a transplantable islet cell tumour of the golden hamster,i.e.dopamine‐4‐O‐glucuronide and 3‐methoxytyramine‐4‐O‐glucuronide. L‐dopa is rapidly metabolized in the tumour to one or both of these glucuronides. Incubation of tumour homogenates in the presence of β‐glucuronidase shows that dopamine‐4‐O‐glucuronide is present in the tumour in extremely high concentrations.
Lactate in Fast and Slow Twitch Skeletal Muscle Fibres of Man during Isometric Contraction
Authors: Tesch Per , Karlsson Jan
Published: December 2008

Concentrations of lactate in fast and slow twitch fibres, respectively, were determined in m. quadriceps femoris after sustained contractions at 25%, 50%, and 75% of maximal voluntary isometric contraction (MVC) until exhaustion as well as after interrupted exercises at 25 % and 50 % MVC. Maximal lactate concentrations were only found at 50% of MVC performed to exhaustion. Lactate concentration was higher in slow twitch (ST) fibres at 50% MVC compared to in ST fibres at 25% MVC, and higher in fast twitch (FT) fibres at 50% MVC compared to in FT fibres at 75 % MVC. After short time isometric exercise (i.e. 75% to exhaustion and 50% and 25% performed for the same period of time as 75% MVC) lactate concentration, expressed as lactate ratio (lactate concentration in FT fibres/lactate concentration in ST fibres) was found to be positively correlated to percent FT fibres (r = 0.89). Lactate ratio ranged 0.5‐2.0, i.e. at onset of isometric exercise, lactate concentration increase was faster in ST fibres in the muscle rich in ST fibres and faster in FT fibres when the muscle was rich in FT fibres.
Effect of Changes in Blood Volume Distribution on Circulatory Variables and Plasma Renin Activity in Man
Authors: Bevegård Sture , Castenfors Jan , Lindblad Lars Erik
Published: December 2008

In 8 healthy subjects the pressure around the lower body was changed to 40 mmHg above (LBPP) and below (LBNP) atmospheric, thereby altering the amount of blood pooled in the lower body. Heart rate, intraarterial blood pressure, central venous pressure, cardiac output (dye dilution technique) and forearm blood flow (venous occlusion plethysmography) were measured. Plasma renin activity was determined with a radioimmunological method. 6 subjects maintained a relative circulatory steady state during LBNP. LBNP caused significant decreases in central venous pressure (CVP), stroke volume and cardiac output (0) with an unchanged mean arterial pressure (MAP). Heart rate (HR) increased significantly. Calculated total peripheral vascular resistance (TPVR) and regional vascular resistance (RVR) in the forearm were significantly increased when measured 5–9 min after the onset of LBNP, whereas plasma renin activity (PRA) showed a definite increase only after 19 min of LBNP stimulation. No correlation was found between the changes in PRA and TPVR or RVR. Increasing the pressure around the lower body (LBPP) resulted in a slight but significant increase in MAP as well as a significant but transient increase in CVP. No significant changes were found in HR, Q or TPVR. In the forearm a decrease in RVR was demonstrated. PRA was not significantly changed. The results demonstrate that peripheral vascular resistance and PRA are both influenced by changes in blood volume distribution, possibly elicited via intrathoracic receptors sensitive to changes in central blood volume and/or CVP. The results also suggest that PRA does not play any significant part in the vasoconstriction during LBNP stimulation.
Renal Hemodynamics in the Perinatal Period
Authors: Aperia Anita , Broberger Ove , Herin Peter , Joelsson Ingemar
Published: December 2008

The perinatal changes in renal hemodynamics have been studied in lambs. Eleven of the lambs were exteriorized, but maintained on placental circulation (fetal lambs). Eight of the lambs were delivered with cesarean section and studied immediately after clamping of the cord (newborn lambs). Nine lambs were delivered spontaneously and studied during the first 9 days of life. Renal blood flow (RBF) was determined by the microsphere method using a sample drawn from the iliac artery as the reference flow. The filtering capacity of the nephrons was evaluated after ferrocyanide injection and dissection of the nephrons. Total RBF did not seem to change much at birth but increased in relation to kidney weight during the first postnatal week. Clamping of the cord did, however, result in a change in intrarenal blood flow distribution, so that in the newborn lambs relatively more of the blood flow was perfusing the outer cortical region. During the first postnatal week there was a slight, but insignificant further relative increase in outer cortical blood flow. The relative increase in outer cortical blood flow at birth was accompanied by an increased frequency of filtering superficial nephrons from 22 to 77 %. Practically all juxtamedullary nephrons were filtering before birth. Three days postnatally 98 % of the superficial and 100 % of the juxtamedullary nephrons were filtering.
Effects of Acetylsalicylate on Alkalinization, Acid Secretion and Electrogenic Properties in the Isolated Gastric Mucosa
Authors: Garner Andrew
Published: December 2008

The effects of acetylsalicylate (ASA) on the in vitro secretory and electrical properties of Necturus and Rana temporaria gastric mucosa have been studied. The gastric antrum alkalinized the luminal surface, while in the fundus it is likely that acidification and alkalinization occur simultaneously and that net secretion is due to the dominance of one or other of these processes. The histamine H2 receptor antagonist Metiamide was used to inhibit acid secretion for studies on fundic alkalinization in Rana temporaria. Submucosal application of 3 mM ASA for 30 min markedly reduced alkalinization in the antrum and the frog fundus. Following removal of ASA there was only partial recovery of this secretion. The drug caused slight inhibition of spontaneous acid secretion in Necturus fundus but not of histamine‐stimulated acid secretion in the frog fundus. Following salicylate removal, the rate of acid secretion increased to a higher level than before administration in both tissues. There was a small flux of ASA across the mucosa which was greatest in the acid secreting frog fundus (4.38μmol cm‐2 min‐1) and least in the antrum (2.19μmol cm‐2 min‐1). Exposure of the gastric mucosa to ASA was generally associated with a fall in transmucosal electric potential difference and short‐circuit current together with an increase in electrical resistance. It is proposed that the greater sensitivity of alkalinization to ASA is responsible for the apparent increase in the rate of acid secretion which occurred.
Adrenergic and Cholinergic Nerves of the Human Urethra and Urinary Bladder. A Histochemical Study
Authors: Ek A. , Alm P. , Andersson K.‐E. , Persson C. G. A.
Published: December 2008

The occurrence and distribution of adrenergic and acetylcholine esterase (AChE) positive nerves in the human urethra and urinary bladder were studied histochemically with the fluorescence method of Falck and Hillarp, and the copper thiocholine method of Koelle and Friedenwald. Both types of nerves were mainly confined to the layers of smooth muscle cells in the walls of the organs. In all parts of the urethra, there was a scanty supply of adrenergic nerves. Few adrenergic nerves were also found in the urinary bladder, except in the trigone area, where they were abundant. AChE‐positive nerves were uniformly and richly distributed in the urinary bladder. Throughout the urethra the distribution of AChE‐positive nerve fibres was uniform, but the number was clearly less than in the urinary bladder. No intramurally located adrenergic or AChE‐positive ganglion cells could be demonstrated.
The Effects of Variations in Extracellular Magnesium Concentration on Electrical and Mechanical Activity in Rat Portal Vein
Authors: Sigurdsson Stefan B. , Uvelius Bengt
Published: December 2008

The effects of various concentrations of extracellular Mg2+ on electrical and mechanical activity of the rat portal vein were studied. The integrated spontaneous contractile activity in the preparation was largest in Mg2+‐free solution, decreased to about 50 %at 1.2 mM Mg2+ and was almost completely abolished at 10 mM Mg2+. Each spontaneous contraction became smaller whereas contraction frequency was less affected. Sucrose gap recordings showed that the reduced spontaneous mechanical output was associated with decreased electrical activity on increasing [Mg2+]0. Increasing [K+]0 from 6 to 12 mM normalized the spontaneous mechanical activity in 10 mM Mg2+ solution. Local registration of electrical activity with 3 extracellular glass capillary electrodes showed that inactive areas developed at the high Mg2+ concentrations. These findings indicate that Mg2+ exerts a hyperpolarizing action on the smooth muscle cell membrane and, at the highest concentration, interferes with intercellular propagation. [Mg2+]0 in the range of 0–10 mM had no effect on the amplitude of K+ (122 mM) contractures at [Ca2+]0± 0.5 mM. At [Ca2+]0 < 0.5 the amplitude diminished with increasing [Mg2+],. The latter observation indicates that Mg2+ can interfere with the Ca2+‐permea‐bility of the depolarized cell membrane. 1 mM EDTA in Na‐tris 0 mM Mg2+ and 0 mM Ca2+ seemed to lower intracellular Mg2+ below the minimum concentration needed for contractile activity.
Extracellular Potassium Concentration in Juvenile and Adult Rat Brain Cortex during Anoxia
Authors: Hansen Anker Jon
Published: December 2008

The extracellular K concentration, ([K]e), in the brain cortex of rats at different ages was measured by means of K+‐sensitive microelectrodes. [K]e was between 3 and 5 mM at all ages. Following nitrogen inhalation there was an increase in [K]e which exhibited a sigmoid pattern in every age group: Firstly, there was a slow rate of rise which was followed by a sudden, steep increase where the [K]e rose to about 70 mM. During the subsequent 5–10 min a plateau value of about 90 mM was reached. The prominent difference between the age groups was the time until the steep rise began. The time to the steep increase in [K]e and the [K]e at the start of the steep increase was inversely related to the age of the animal. A close relation was found between the time to the start of the steep increase and the time to the last gasp during nitrogen breathing (r ‐ 0.98). It is suggested that the different resistence to anoxia in young and adult animals is related to differences in the ability to keep near normal potassium gradients across the cells in the brain.
Distribution of Coronary Blood Flow in the Left Ventricular Wall of Dogs Evaluated by the Uptake of Xe‐133
Authors: Bagger Henning
Published: December 2008

The distribution of coronary blood flow was estimated in anesthetized dogs by counting the activity in tissue blocks of the left ventricular free wall immediately after bolus injection of Xe‐133 into the aortic root. No differences in the uptake of isotope were observed between the apex and the base of the heart; between areas supplied by the anterior descending and circumflex branches of the left coronary artery; or between the endo‐ and epicardial halves of the wall. In most experiments a bolus injection of the isotope into the left coronary artery was followed by a difference in activity between areas supplied by the left anterior descending and left circumflex branches. This indicated inadequate mixing of blood and isotope in the main stem of the artery. The uneven distribution did not result in differences between the epi‐ and endocardial activity concentrations. The results from one normal, anesthetized dog in which tissue activities were measured after constant rate infusion of Xe‐133 into the left coronary artery for 8 min were in accordance with the general assumption of equal epiand endocardial volumes of distribution (values of Zs).
Effect of Hypoxia on Mitochondrial Mass and Cytochrome Concentrations in Rat Heart and Liver during Postnatal Development
Authors: Kinnula Vuokko L. , Hassinen Ilmo
Published: December 2008

Cytochrome concentrations of rat heart and liver mitochondria were measured postnatally from newborn animals to young adults. Mitochondrial cytochrome aa3 concentration increased shortly after birth in both tissues, this concentration being in a newborn animal 0.149 ± 0.027 nmol/mg protein in liver and 0.333 ± 0.082 nmol/mg protein in heart. The respective values from a two week old animal were 0.216±0.031 and 0.583 10.100. Postnatally cytochromes c±c1 and b increased markedly in the heart, but in the liver of newborn animals the cytochrome content was more close to the adult values. The amount of mitochondrial protein increased after birth, too. In a newborn animal the mitochondrial protein values were 39.7 ± 3.6 mg/g wet weight in liver and 26.6± 6.5 mg/g wet weight in heart. In adult animals the respective values were 71.5 ± 4.8 and 80.7± 13.1. The effect of postnatal hypoxia (10% O2, 24 h and 48 h) on liver and heart mitochondrial cytochrome concentration and protein values of newborn animals were investigated. During hypoxia the amount of mitochondrial protein remained about at the level of a newborn animal. The postnatal increase in the mitochondrial cytochrome concentration, which was smaller in the liver than in the heart, was also inhibited by hypoxia.
The Ability of ATP‐Free Granule Material from Bovine Adrenal Medulla to Bind Inorganic Cations and Biogenic Amines
Authors: Uvnäs Börje , ÅBorg Carl‐Hugo
Published: December 2008

Bovine adrenal medullary granules isolated by miliipore filtration were depleted of CA and ATP by dialysis. The resulting material showed an ability to bind inorganic cations and biogenic amines in a concentration‐dependent manner. The similarity of the uptake curves, the identical uptake maxima and the narrow pH range (between 4–7) over which the uptake of the inorganic and organic cations took place indicated a binding of these ions to common sites. In addition, the fact that all the uptake curves fitted the Rothmund‐Kornfeld equation for cation exchangers corroborated the cation exchanger properties of the dialyzed granule material. The CA binding capacity corresponded to 20–30% of the normal CA content of bovine medullary granules.
Indirect vascular actions of (Gln4)‐neurotensin in canine adipose tissue
Authors: Rosell Sune , Rökaeus ÅKe , Ding Chang  , Folkers Karl
Published: December 2008

The vasoconstrictor action of the tridecapeptide (Gln4)‐neurotensin has been studied in subcutaneous adipose tissue in the inguinal region of anesthetized dogs. Close intra‐arterial infusion of (Gln4)‐neuroten‐sin, 30–120 pmol X kg‐1 b.wt. X min‐1, elicited similar vasoconstrictions in the adipose tissue on the infusion side and on the contralateral side. This suggests that (Gln4)‐neurotensin must enter the general circulation before it can elicit vasoconstriction. Removal of parts of the gastrointestinal tract did not change the vasoconstrictor response. Thus, there is no indication of release of vasoactive substances from the gastrointestinal tract by (Gln4)‐neurotensin. Infusion into the portal vein elicited the same vasoconstriction in adipose tissue as the same dose administered i.v. It is suggested that the vasoconstrictor action in adipose tissue is not caused by (Gln4)‐neurotensin per se. Instead, vasoactive substance(s) may be formed from (Gln4)‐neurotensin.
Aspects on diamine oxidase activity and its determination
Authors: Andersson Anne‐Charlotte , Henningsson Stig , Persson Lo , Rosengren Elsa
Published: December 2008

Homogenate of guinea‐pig liver and human placenta, tissues known to be rich in diamine oxidase, were incubated with 14C‐putrescine and the metabolites formed were determined. In the incubate of guinea‐pig liver, the major metabolites were GABA and some unidentified compound(s); Δ1‐pyrroline and 14CO2 were also obtained. In both the maternal and fetal parts of human placenta, radioactive GABA and the unidentified compound(s) as well as Δ1‐pyrroline were found. The results indicate that GABA is an important intermediate in putrescine metabolism. Determination of the amount of Δ1‐pyrroline is thus not well suited as a measure of the diamine oxidase activity in tissues.
Tension‐length behaviour of a molluscan smooth muscle related to filament organisation
Authors: Cornelius F. , Lowy J.
Published: December 2008

Under optimal activation conditions we obtain an active tension‐length curve with a well‐defined plateau region. The plateau can be explained in terms of a sliding filament mechanism in which double overlap of the thin filaments does not interfere with cross‐bridge formation between thick and thin filaments of the appropriate polarity.