bluuebunny/crossref_metadata_2025 huggingface dataset:
Specific and Unspecific Removal of Circulating Noradrenaline in Pulmonary and Systemic Vascular Beds in Man
Authors: Stjärne Lennart , Kaijser Lennart , Mathé Aleksander , Birke Gunnar
Published: December 2008

In order to study the extent and degree of specificity of the removal of circulating noradrenaline (NA) from the blood stream, during a single passage through the vascular beds of the lungs and of the forearm musculature of unanaesthetized, healthy young men, the following radiometric method was used: A mixture of3H‐NA with14C‐inulin and125I‐labelled human serum albumin was injected proximally to the bed under study; six serial blood samples were drawn distally to it, with about 15 s interval, and the disappearance of3H‐NA relatively to that of14C‐inulin and125I‐albumin was determined.3H‐NA was found to be removed from the blood stream in both these vascular beds. However, in the forearm the removal of3H‐NA was much greater, and apparently to a large extent due to specific trapping in the tissues, since the clearance of3H‐NA over the vascular bed of the forearm markedly exceeded that of 14C‐inulin. During passage through the lungs removal of3H‐NA was less marked, and apparently largely unspecific, since it was initially essentially equal to that of14C‐inulin. This suggests that removal of circulating ergones of small molecular sire, from the blood stream passing through the lungs, may occur initially by unspecific filtration/diffusion. Their subsequent fate would depend on whether the extraluminal tissues, supplied by the lung circulation, possess specific mechanisms for concentrating and/or inactivating each particular compound.
Rat Liver Mitochondrial Enzyme Activities in Hypoxia
Authors: Kinnula Vuokko L.
Published: December 2008

Rat liver mitochondrial enzyme activities were measured after exposing the animals to the atmospheric pressure of 380 mm Hg for 5 h and 14 days. Succinate dehydrogenase and succinate oxidase activities increased significantly during the hypoxic period of 14 days. No change was observed in cytochrome oxidase activity. Malate dehydrogenase and glutamate dehydrogenase activities increased somewhat, but not significantly. The efficiency of oxidative phosphorylation (the ADP: O ratio) in the isolated mitochondria remained unchanged. The exact mitochondrial protein values showed a 15% decrease as compared with the control group. The concentrations of cytochromes did not change significantly in the hypoxic group. During the short hypoxic period succinate dehydrogenase, succinate oxidase and cytochrome oxidase activities increased as compared with those in the control group.
Radioactively Labelled Microspheres in Regional Cerebral Blood Flow Determinations A study on monkeys with 15 and 35 μm spheres
Authors: Alm Albert
Published: December 2008

15 μm and 35 μm radioactive microspheres, differently labelled, were used simultaneously for rCBF‐determinations in monkeys. Flow values calculated from data for 35 μm spheres were 27±7 g/min per 100 g higher for grey matter and 10±3 g/min per 100 g lower for white matter than flow values calculated from 15 μm spheres, while both sphere sizes resulted in similar values for the choroid plexus. A large number of 35 μm spheres were trapped in extracerebral pial arterioles. It is concluded that entrapment in relatively large arterioles of the 35 μm spheres explains the differences in flow values, and that this invalidates the use of 35 μm spheres, and larger, in rCBF‐determinations.
Cholinergic Receptors at Denervated Mammalian Motor End‐Plates
Authors: Frank Erik , Gautvik Kaare , Sommerschild Henrik
Published: December 2008

The number of acetylcholine receptors at normal and denervated end‐plates in rat soleus muscles was studied using the binding of [125I] α‐bungarotoxin as a quantitative assay. Normal end‐plates bound several thousand times as much toxin as equal areas of extra‐synaptic muscle membrane. After short‐term denervation (up to 2.4 weeks) the extrajunctional binding increased, but there was no change in specific binding to the motor end‐plate. Denervation for longer periods (up to 7 weeks) reduced binding sites at the end‐plate by up to 60–70%. Direct electrical stimulation of these muscles for the entire period of denervation did not prevent the loss of junctional binding sites even though it was adequate to abolish the increase in extrajunctional toxin binding. In contrast, denervated end‐plates on muscle fibres cross‐innervated by a Foreign nerve at a distant location continued to bind normal amounts of toxin for over four months.
The Pulmonary Vasoconstrictor Response to Hypoxia: Effects of Inhibitors of Prostaglandin Biosynthesis
Authors: Vaage J. , Bjertnæs L. , Hauge A.
Published: December 2008

The main purpose of the present work was to determine whether prostaglandins (PGs) synthetised in the lungs mediate the vasoconstrictor response to acute alveolar hypoxia. Isolated and ventilated lungs of rats were perfused at 37°C with homologous blood at constant‐volume, pulsatile inflow, and pressor responses to 3 min periods of standardized ventilation hypoxia recorded. Indomethacin, sodium meclofenamate and acetylsalicylic acid (all 100 μg/ml), which are potent inhibitors of PG biosynthesis, did not reduce the hypoxic vasoconstrictor response. Sometimes they even enhanced this response. We conclude that PGs do not mediate the hypoxia‐induced vasoconstriction. We suggest that vasodilatory PGs might act to reduce and modify pulmonary arterial hypertension due to hypoxia.
Reflexogenic Contraction of the Ileo‐Cecal Sphincter in the Cat Following Small or Large Intestinal Distension
Authors: Pahlin P.‐E. , Kewenter J.
Published: December 2008

The effect of distension of a small or large intestinal loop on the ileo‐cecal sphincter (ICS) in the cat was studied with a flow‐recording technique. Distension of a small or large intestinal loop, isolated from the adjacent intestine, but with its mesenteric vascular and nervous supply intact, elicited a contraction of the ICS concomitant with an inhibition of the adjacent large and small intestinal motility. Vagal and pelvic nerve section did not affect the response to distension of the ICS nor exclusion of the adrenal glands from the circulation. The sphincter reflex could be entirely or almost entirely eliminated by cutting both the splanchnic and lumbar colonic nerves, but not one or the other. Spinal anesthesia blocked the reflex response indicating a spinal reflex arc. The reflex persisted after atropine and propranolol, while both guanethidine and phenoxybenzamine completely abolished the reflex contraction of the sphincter.

The present results indicate that the excitatory intestino‐ileo‐cecal sphincteric reflex is a spinal reflex with the main afferent and/or efferent fibres located within the major splanchnic and lumbar colonic nerves. The excitatory motor response in the sphincter is adrenergic and mediated viaα‐receptors.
Cardiopulmonary Blood Volumes at Rest and during Muscular Exercise Measured by 113mIn Radiocardiography
Authors: Kuikka J. , Psc>yörälä T. , Lehtovirta P. , Rekonen A.
Published: December 2008

Cardiac output, stroke volume, right heart and left heart blood volume, pulmonary blood volume and pulmonary mean time were measured at rest and during muscular exercise in 14 healthy subjects in the supine position. The method used was 113mIn radiocardiography measured precordially with a single detector. The results were analyzed with a minicomputer by a modified gamma function fitting method. The increase in cardiac output during exercise was 140 per cent (p < 0.001). The stroke volume increased 15 per cent (p < 0.05) in subjects with heart rates < 160 beats/min, and decreased in subjects with heart rates ≥ 160 beats/min. The right heart blood volume decreased from 115 ml/m2 to 105 ml/m2 (5 per cent; p>0.1) and the left heart blood volume decreased from 115 ml/m2 to 105 ml/m2 (5 per cent; p < 0.01). The total heart blood volume thus decreased from 120 ml/m2 to 110 ml/m2 (5 per cent; p < 0.01). The pulmonary blood volume showed a corresponding increase from 250 ml/m2 to 280 ml/m2 (12 per cent; p < 0.005), and the cardiopulmonary blood volume did not markedly change (485 ml/m2 and 495 ml/m2). Pulmonary mean time decreased from 5.0 s to 2.4 s (52 per cent; p < 0.001).
Motor Unit Responses in the Lateral Rectus Muscle of the Cat: Intracellular Current Injection of Abducens Nucleus Neurons
Authors: Goldberg S. J. , Lennerstrand G. , Hull C. D.
Published: December 2008

Single motor units of the cat's lateral rectus muscle were activated with short intracellular current pulses delivered through an intracellular micropipette penetrating a single motoneuron, and the mechanical responses in the muscle were recorded. Lateral rectus unit responses fell within the same range as those obtained earlier with extracellular stimulation of inferior oblique units, confirming that in the latter case single and not multiple motor units had been studied. It was also found that both fast and slow contracting muscle units were connected to fast conducting, large size motoneurons. The organization of motor unit recruitment in eye movements would thus seem different from the recruitment pattern in limb muscles.

Intracellular stimulation of abducens nucleus “interneurons” did not initiate contractions at the ipsilateral lateral rectus muscle. These “interneurons”, therefore, did not appear to have excitatory inputs to the abducens motoneurons, but may be involved in relaying information to the other extraocular muscle nuclei or to other brain centers.
A Method for Determining Blood Flow and Oxygen Consumption in the Rat Brain
Authors: Nilsson B. , Siesjö B. K.
Published: December 2008

Cerebral blood flow (CBF) and cerebral metabolic rate for oxygen (CMRo2) were measured in rats under nitrous oxide anaesthesia, using a133Xenon modification of the Kety and Schmidt inert gas technique with sampling of cerebral venous blood from the retroglenoid vein. Extracerebral contamination of the venous blood sampled was studied by comparing the rates at which the activity of133Xenon decreased in blood and tissues. Contamination was avoided by gentle compression of the contralateral retroglenoid vein during sampling. CBF and CMRo2of the rat brain were 80±2 and 7.6 ± 0.2 ml·(100 g)‐1, min‐1, respectively. These values are about 25% lower than those previously obtained for cerebral cortical tissue under similar conditions. Induced hypercapnia (Paco2about 70 mm Hg) or hypocapnia (Paco215–20 mm Hg) gave rise to expected changes in CBF but did not alter CMRo2The CMRo2of the rat brain is at least twice that of the human brain. This species difference, which is similar to that previously reported for the oxygen uptake of cerebral tissuein vitro, probably reflects on inverse relationship between brain weight and neuronal packing density.
Mechano‐Elastic Properties of Human Muscles at Different Temperatures
Authors: Asmussen Erling , Bonde‐Petersen Flemming , Jørgensen Kurt
Published: December 2008

The effect of changes in the muscle temperature on their ability to store elastic energy was studied by having 5 trained subjects perform maximal vertical jumps on a force platform, with and without counter movement, at muscle temperatures between about 32°C and 37°C. The results showed that the heights of vertical jumps were considerably reduced at lowered temperature, but the gain in height after a counter movement in the form of a jump down from a height of 0.4 m over the force platform, was significantly higher in the cold condition. To test whether this was due to an increased stiffness of the muscles, experiments with imposed sinusoidal length variations at 14 Hz were performed. Δforce ×Δlength‐1 (i.e. stiffness) increased with isometric tension independent of muscle temperature. Experiments in which the rate of tension development and relaxation in voluntary maximal isometric contractions were measured at different muscle temperatures showed that maximal isometric tension changed by less than 1 % per degree but the rate of tension development and relaxation by 3–5 % and 5 % per degree, respectively, in the temperature range studied (30° to 40°). These data may be explained by the hypothesis that the series elastic components of the active muscle are located in the cross‐bridges between myosin and actin filaments. The storage of elastic energy would be enhanced if the rate of breaking of these bridges were decreased at lower temperatures.
The Effects of Estrogens on Regional Adipose Tissue Cellularity in the Rat
Authors: Krotkiewski Marcin
Published: December 2008

The effects of high and low dose estrogen administration on adipose tissue cellularity and metabolism were investigated and compared with the effect of total starvation in female rats. Total starvation in female rats resulted in local fat cell size decrease which was, in different adipose tissue regions, directly proportional to the primary fat cell size. Thus, the largest fat cell size decrease was observed in the parametrial depot of adipose tissue with primarily the largest adipocytes and the smallest decrease of fat cell size in the subcutaneous adipose tissue, with primarily the smallest adipocytes. High doses of estrogen (Estradurin®—120 μg/km/gonth) resulted in a body and adipose tissue weight decrease after 10 weeks treatment. Contrary to the starvation effect the greatest fat cell size decrease was observed in the subcutaneous depot with primarily the smallest adipocytes. Lower estrogen dose (60 μg/kg/month) resulted, after 4 weeks treatment, in weight increase of adipose tissue. Fat cell size increased most in the parametrial depot—an adipose tissue region with primarily the biggest adipocytes. This is in contrast to the situation after insulin treatment and overfeeding which produce the largest size increase in the region with the smallest fat cells, and can be interpreted as evidence for regional specificity of the estrogen effect on fat cells.
Lack of Specificity of Motoneurone Responses to Microiontophoretically Applied Phenolic Amines
Authors: Engberg I. , Flatman J. A. , Kądzielawa K.
Published: December 2008

Intracellular recordings from spinal motoneurones have revealed that iontophoresed noradrenaline (NA) causes a membrane hyperpolarization, sometimes leading to a block of spike generation (Curtis 1968, Phillis, Tebëcis and York 1968). Similar alterations of membrane activity were produced by serotonine and histamine. The hyperpolarization is possibly due to a reduction of the resting sodium permeability (PNa) as the membrane conductance is decreased during NA application (Engberg and Marshall 1971, 1973)—a similar mechanism as in the slow synaptic inhibition in bullfrog sympathetic ganglion cells (Weight and Padjen 1973)—or it may be due to an activation of electrogenic ion transport as has been suggested for cerebellar Purkinje cells (Siggins et al. 1971).
Serum Luteinizing Hormone and Testosterone after Sexual Stimulation in Male Rabbits
Authors: ÅGmo Anders
Published: December 2008

Sexual activity has been found to increase plasma testosterone in males of several mammalian species, including the rabbit (Saginor and Horton, 1968, Haltmeyer and Eik‐Nes, 1969) and the rat (Purvis and Haynes, 1974). This increase was attributed to a release of LH from the pituitary (Saginor and Horton, 1968) and data obtained in the male rat supports this hypothesis (Taleisnik, Caligaris and Astrada, 1966). However, many recent studies have failed to detect any changes in LH levels following copulation in males (e.g. Gombe, Hall, McEntee, Hansell and Pickett, 1973).
(Na+, K+)‐Activated ATPase in Microsomes from Mouse Pancreatic Islets
Authors: Formby B. , Capito K. , Hedeskov C. J.
Published: December 2008

The intracellular concentration of Na+ in mouse pancreatic β‐cells (95 meqv/l, Sehlin and Täljdedal 1974) is so high that the active pump mechanism to extrude Na+ must have a low activity compared with that of neurone and muscle cells (Bonting 1971).
The vagal release of 5‐hydroxytryptamine from enterochromaffin cells in the cat
Authors: Ahlman H. , Bhargava H. N. , Donahue P. E. , Newson B. , Gupta T. K. Das , Nyhus L. M.
Published: December 2008

Enterochromaffin cells (EC) from the cat duodenum were studied before and after electrical efferent stimulation of the cervical vagal by means of electron microscopy and fluorescence histochemistry according to the Hillarp‐Falck technique. From the same animals portal blood plasma was assayed for serotonin (5‐HT) at various stages of the nerve stimulation. Within 15 min after the onset of vagal nerve stimulation there was a more than twofold increase of the portal 5‐HT levels, which returned to normal after cessation of stimulation. There was also a pronounced reduction in the fluorescence intensity of EC demonstrating a lowered intracellular 5‐HT level. Ultrastructurally there was evidence for basal exocytosis as well as for a release of osmiophilic material from the EC directly into the gut lumen after nerve stimulation. Together, these observations strongly suggest a vagally induced 5‐HT release from EC in the cat.
Resetting of cardiac C‐fiber endings in the spontaneously hypertensive rat
Authors: THORÉN P. , NORESSON E. , RICKSTEN S.‐E.
Published: December 2008

The characteristics of 11 left atrial receptors in 9 adult male spontaneously hypertensive rats (SHR) were investigated. All the receptor afferents were non‐medullated with conduction velocities from 0.5 to 1.5 m/s. Elevation of left atrial pressure during graded aortic occlusion always induced a marked increase in receptor discharge with maximal frequencies ranging from 29 to 70 Hz. The threshold for activation was from 7.5 to 13 mmHg in mean left atrial pressure (mean ± S.E., 10.2±0.6 mmHg). Upon atrial distension all the receptors displayed a clear rhythmicity and the discharge correlated mainly with the v‐wave, indicating distension as the cause of receptor activation. The relationship between the mean left atrial pressure and the frequency of discharge was constructed for all the receptors and compared with similar data obtained from normotensive control rats (NCR) (Thorén et al. 1979). It was then obvious that the left atrial receptors are reset in SHR probably secondarily to a decreased distensibility of the left atrium.
Distribution of blood flow in the dog kidney: I. Saturation rates for inert diffusible tracers,125I‐iodoantipyrine and tritiated water, versus uptake of microspheres under control conditions
Authors: CLAUSEN G. , HOPE A. , KIRKEBØ A. , TYSSEBOTN I. , AUKLAND K.
Published: December 2008

Disparate reports on intrarenal blood flow distribution prompted a direct comparison between microspheres (Ms) and inert diffusible tracers (DT). The “tissue sampling technique” for estimating local flow with DT (Kety) was adapted for the dog kidney, using125I‐iodoantipyrine (I‐Ap) and tritiated water (THO). Ms (15 μm) were injected 2–3 min prior to 10–15 s DT infusion made during continuous 1 s arterial blood sampling. Tracers were measured in 7 to 20 samples from each of the following zones: Outer, middle and inner cortex (C1, C2, C3), outer and inner halves of outer medulla (OM1, OM2), and inner medulla (IM).I‐Apand THO gave closely similar flow distributions, and average total renal blood flow (RBF) of 3.90 and 3.78 as compared to 3.94 ml/min g with Ms. Flow in C2(ml/min g) was similar with all tracers, and in per cent thereof average local flows were: C1102, C370, OM134, OM212, and IM 2 with DT versus 117, 53, 12, 3, and 0 with Ms. Zonal flow fractions of total RBF obtained with DT were: C10.41, C20.33, and C3+medulla 0.26 versus 0.51, 0.33 and 0.16 with Ms. Thus, a Ms surplus in C1relative to DT flow, representing 10% of total RBF, matched a Ms deficit in C3+medulla. This disparity might result from: (1) Failure of Ms to enter deep afferent arterioles in proportion to blood flow, (2) diffusion of DT from deep portions of the interlobular arteries, and/or (3) postglomerular inward flow of blood and DT.
The effect of transmural field stimulation on the serotonin content in rat duodenal enterochromaffin cells—in vitro
Authors: PETTERSSON G. , AHLMAN H. , DAHLSTRÖM A. , KEWENTER J. , LARSSON I. , LARSSON P. A.
Published: December 2008

The effect of transmural field stimulation (TFS)—in vitro—on the serotonin (5‐HT) content in enterochromaffin cells (EC) in rat duodenum was studied with a cytofluorimetric method. TFS caused a significant 25% decrease of 5‐HT in EC. The presence of tetrodotoxin or d, 1‐propranolol in the stimulation bath antagonized the effect of TFS. In biopsies from rats pretreated with 6‐OH‐dopamine TFS had no effect of the 5‐HT content in EC. The results of the present study strongly suggest, that the TFS induced decrease in 5‐HT content is due to a direct neural, probably β‐adrenoceptor mediated, influence on the EC.
On the chromaffin system of the African lungfish, Protopterus aethiopicus1
Authors: ABRAHAMSSON TOMMY , HOLMGREN SUSANNE , NILSSON STEFAN , PETTERSSON KNUT
Published: December 2008

The distribution of chromaffin tissue was studied in the African lungfish using Falck‐Hillarp fluorescent histochemistry together with quantitative analysis of catecholamines in plasma and tissue extracts. Intensely fluorescent cells form chromaffin tissue in the wall of the atrium, the wall of the most anterior part of the left cardinal vein and the walls of the segmentally arranged intercostal arteries. The arrangement thus appears to be a combination of the situations in cyclostomes, elasmobranchs and teleosts. Adrenaline is present in larger quantities than noradrenaline in the intercostal arteries and the cardinal vein, while noradrenaline dominates in the atrium. During “stress” induced by physical disturbance of the animals, a strong increase in especially the noradrenaline concentration of the plasma was detected.
Adrenergic and cholinergic effects on the heart, the lung and the spleen of the African lungfish,Protopterus aethiopicus
Authors: ABRAHAMSSON TOMMY , HOLMGREN SUSANNE , NILSSON STEFAN , PETTERSSON KNUT
Published: December 2008

Effects of adrenergic and cholinergic drugs were studied on isolated preparations from the heart, the lung and the spleen of the African lungfish. In addition, a nerve‐lung preparation was employed for the study of the autonomic nervous control of the lung. Falck‐Hillarp fluorescent histochemistry was used in the search for adrenergic neurons in the sympathetic chain and tissues. The Protopterus lung received a cholinergic excitatory innervation via the pulmonary branches of the vagi. The presence of parasympathetic ganglia in the lung tissue is indicated. Adrenergic drugs, when producing a response, either contracted or relaxed lung strips. Spleen strips were contracted by cholinergic drugs acting on muscarinic receptors and, to a lesser extent, by adrenergic drugs. A strong negative inotropic effect was produced by carbachol on paced atrial but not ventricular strips, while adrenaline increased the contraction force in ventricular but not atrial strips. The sympathetic ganglion cells did not contain enough catecholamines to give off any visible fluorescence, nor was it possible to show any adrenergic nerve terminals in the tissues studied. It is concluded that the adrenergic control in the lungfish is mainly due to circulating catecholamines, rather than adrenergic nerve fibres, since concentrations of catecholamines in Protopterus plasma are high enough to affect the spleen, lung and ventricle.
Catecholamine synthesis in the chromaffin tissue of the African lungfish, Protopterus aethiopicus
Authors: ABRAHAMSSON TOMMY , JÖNSSON ANN‐CATHRINE , NILSSON STEFAN
Published: December 2008

The activities of dopamine‐β‐hydroxylase (DBH, E.C. 1.14.17.1) and phenylethanol‐N‐methyl transferase (PNMT, E.C.2.1.1.10) were determined in tissue homogenates from the chromaffin tissue containing atrium and intercostal arteries from the African lungfish. Clearly measurable activities of DBH were found in both kinds of tissues, while PNMT activity was ascertained only in the intercostal arteries. The activity of DBH in the atrium indicates a possibility for local synthesis of the large amounts of catecholamines, especially noradrenaline, found in this tissue. Catecholamines synthetized in and released from the chromaffin tissues of Protopterus, may be of great importance for the adrenergic control in this animal in the absence of a well developed sympathetic nervous system.
Estimation of cerebral extraction of circulating compounds by the brain uptake index method: Influence of circulation time, volume injection, and cerebral blood flow
Authors: HARDEBO J. E. , NILSSON B.
Published: December 2008

The Oldendorf “brain uptake index” method for estimating and characterizing the transport of circulating substances across the blood‐brain barrier in the rat has been widely applied. The present study illustrates that minimizing the volume injected into the circulation to 10 μl or less is necessary. Otherwise the flow artefacts, induced by the injected volume and the rate of injection, will influence the index. This principle is also relevant to techniques using intracarotid injections for the direct study of cerebral blood flow. The study also elucidates the need for reducing the circulation time after injection to about 5 sec, to avoid artefacts due to metabolism and back diffusion to the circulation of the substances studied.
Chloride transport by self‐exchange and by KCI salt diffusion in gramicidin‐treated human red blood cells
Authors: CASS ALBERT , DALMARK MADS
Published: December 2008

The permeability of gramicidin‐treated human red blood cell membranes to K+ and CI‐ has been measured at normal ionic strength (1) by tracer exchange at steady‐state distribution of salt, and (2) by net transport of salt in the presence of a salt concentration gradient. Under both conditions KCI was the only inorganic salt in cells and medium. In the studies of self‐exchanges the electrical driving force on the ions was zero. Calculation of permeability coefficients from net salt transport was simplified because the experiment was designed as a special case of the Nernst‐Planck diffusion regime, i.e. the single salt case. Gramicidin altered the cell membranes from being anion to become cation selective. Gramicidin increased the potassium exchange without affecting, the chloride exchange measurably. The chloride exchange showed saturation kinetics as does chloride exchange in normal cells. The net transport of KCI in the presence of a constant concentration gradient increased to a constant value with increasing gramicidin concentration. At high gramicidin concentrations (0°C, pH 7.2) the “chloride permeability coefficient” calculated from tracer exchange (1.9×10‐6 cm/s) was 290 times the chloride permeability coefficient calculated from net salt transport (0.65×10‐8 cm/s). The latter value corresponds to a chloride conductance of 4.2×10‐6 ohm‐1 cm‐2. The chloride permeability coefficient was 2.1×10‐8 cm/s at 25°C (pH 6.8) indicating a value of 3 for the Q25. It appears that normal red cells are anion selective in the sense that anion permeability exceeds cation permeability with a factor of more than a hundred between 0°C and body temperature. The anion exchange, i.e. the Hamburger shift, is a tightly coupled transport process which is several orders of magnitude faster than anion transport by salt diffusion.
Metabolic properties of nerve endings isolated from rat brain
Authors: JANSSON S.‐E. , HÄRKÖNEN M. H. , HELVE H.
Published: December 2008

Energy metabolism was studied in nerve endings isolated from 3‐week‐old rat brain. Concentrations of glycogen, glucose, ATP, phosphocreatine and lactate were lower in synaptosomes than in the intact brain. The consumption of these endogenous substrates, the ability to generate high‐energy phosphate, and the production of ammonia were determined in aerobic and anaerobic conditions. Unlike nerve tissue in general, synaptosomes preferentially utilized endogenous ATP and phosphocreatine stores which, on incubation in the absence of exogenous substrates, were emptied long before glycogen stores were exhausted. The optimal medium for respiratory studies was found to have electrolyte concentrations equal to the extracellular fluid. The synaptosomes had an endogenous respiration rate of 6.3 nmol O2 mg prot. min, measured with an oxygen electrode, and it probably reflects consumption of their glycogen stores. Glucose usually had no effect on the respiration rate of synaptosomes, but sometimes increased it slightly. However, after incubation in the presence of arsenate synaptosomes showed an increase in respiration when glucose was added. ADP, when added with glucose, also stimulated respiration. Pyruvate and succinate always increased respiration, succinate usually having the stronger effect. The present results show that isolated nerve endings are metabolically intact, which justifies their use in research on neurotransmission. In addition, opposite to the present consensus, synaptic transmission does not seem primarily to depend on the availability of glucose but rather on local stores of high‐energy phosphate compounds.
Aggression‐provoked renin release from extrarenal and extrasubmaxillary sources in mice
Authors: BING JENS , POULSEN KNUD
Published: December 2008

In submaxillary sialoadenectomized and nephrectomized mice aggressive behaviour provoked 5 to 40‐fold increases in plasma renin concentration. The changes in renin concentration with time were different in different groups of confronted mice with only partial correlation between the pattern and the observable degree of fight. The changes were similar in sialoadenectomized mice with untouched kidneys as in sialoadenectomized and nephrectomized, indicating that aggression causes no measurable, if any, renal renin release. Repeated aggression with 2 hourly intervals provoked repeated renin relase from extrarenal and extrasubmaxillary sources. The renin concentrations of different organs showed the same mutual relationship as in other mammals, but were about 10‐fold higher. Splenectomy was without effect on the aggression‐provoked renin release. Antibodies against pure mouse renin neutralized the renin in plasma and organs, which contained only insignificant, if any, pepsin activatable inactive renin. Adrenaline, apomorphine, carbachol and dihydralazine were as isoprenaline and noradrenaline without effect on renin release in sialoadenectomized and nephrectomized mice.
Changes in lipoprotein‐lipase activity and lipid stores in human skeletal muscle with prolonged heavy exercise
Authors: LITHELL HANS , ÖRLANDER JAN , SCHÉLE RICKARD , SJÖDIN BERTIL , KARLSSON JAN
Published: December 2008

Lipoprotein‐lipase (LPL) activity and intracellularly stored triglycerides were determined in muscle biopsies taken before and after an 85 km skiing race from 7 volunteers. The triglyceride stores were larger in slow twitch than in fast twitch fibres (proportions 5: 1 before the race). The LPL activity increased and the triglyceride stores in slow twitch fibres decreased during the race. The best trained subjects had the largest TG stores before the race and their TG stores also decreased most during the race. These subjects also had very small increases of LPL activity. The least trained subject on the other hand showed a 6‐fold increase of LPL activity. The high post‐race LPL activity in less trained subjects indicates a higher capacity for uptake of fatty acids from serum TG as compared to the more trained subjects.
The effect of ingestion of amino acids, glucose and fat on circulating neurotensin‐like immunoreactivity (NTLI) in man
Authors: ROSELL SUNE , RÖKAEUS ÅKE
Published: December 2008

The effect of ingestion of amino acids (Vamin N), glucose, and fat (Intralipid) on the concentration of neurotensin‐like immunoreactivity (NTLI) in plasma was determined in 6 healthy male volunteers. After ingestion of Intralipid (55 ml, 200 mg·ml‐1) there was a significant increase in the plasma concentration of NTLI. The calculated integrated total NTLI response (6.7 ± 2.5 nM over 180 min) was statistically significant. Although isocaloric amounts of Vamin and glucose also increased the plasma concentration of NTLI, these increases were not statistically significant. The data indicate that fat is an important stimulus for the release of NTLI from the small intestine. It is suggested that neurotensin, or a metabolite, in blood may be a hormone involved in the postprandial inhibition of gastric motility and gastric acid secretion elicited from the small intestine.
Effects of rubidium, caesium, strontium, barium and lanthanum on ionic currents in myelinated nerve fibres from Xenopus laevis
Authors: ÅRHEM PETER
Published: December 2008

A comparative analysis of the effects of externally applied Rb+, Cs+, Sr2+, Ba2+ and La3+ on myelinated fibres under potential clamp conditions was made. The ions Cs+, Ba2+ and La:l+ (belonging to groups 1a, 2a and 3a of period 6 in the periodic system) were found to affect the K system in specific ways. Ba2+ and La3+ reduced the outward K+ current associated with positive potential steps; the effect of La3+ being larger than that of Ba2+. The effect of Ba2+ depended on the K+ concentration. Cs+, Ba2+ and La3+ reduced the inward K+ tail current at repolarisation in solutions with high K+ concentration. Cs+ and Ba2+ caused a rectification of the K+ current, i.e. they reduced the inward tail current proportionally more than the outward steady state current. The effect of Baz+ could not be described as a simple reduction of the permeability constant p¯K. Rb+ was found to affect the time course of the K system by increasing the rate constant βn. Sr2*, Ba2+ and La3+ reduced the permeability constant p¯Na. These ions also shifted potential dependent parameters in general along the potential axis. The effect of La3+ was larger than that of Sr2+ and Ba2+. Cs2+, Ba2+ and La3+ reduced the p‐current, Ba2+ and La3+ the leak conductance.
Effects of physical training on metabolism of connective tissues in young mice
Authors: SUOMINEN HARRI , KIISKINEN ANJA , HEIKKINEN EINO
Published: December 2008

The effects of physical training on the metabolism of collagen, calcium and glycosaminoglycans in various connective tissues were studied in male NMRI mice. The mice to be trained and their controls were about 3 weeks old (expt. I) and 8 weeks old (expt. II) at the commencement of training. The training was performed on a 5° inclined treadmill 5 days a week for 4 weeks in expt. I and for 3 weeks in expt. II. The daily exercise time was progressively increased from 20 min in the first week up to 80 min in the third week. The incorporation of 3H‐proline to collagen hydroxyproline was increased by training in long bones, skeletal muscle and Achilles tendon, whereas the incorporation of 35S‐sulphate into glycosaminoglycans of bones was lower for the trained compared to the control mice. The differences between the two groups in the incorporation of 45calcium were negligible. The results indicate that the metabolism of collagen is accelerated by physical training in several connective tissues in young rapidly growing mice, whereas the metabolism of glycosaminoglycans remains uneffected or is even retarded.
Alkali metal cation transport through the human erythrocyte membrane by the anion exchange mechanism
Authors: FUNDER J.
Published: December 2008

This work deals with the possibility that cations may be transported through the human red blood cell membrane as negatively charged ion pairs of the type XCO3‐. Passive sodium influx into human erythrocytes was increased 4‐fold when 150 mM chloride was substituted with bicarbonate in the medium. This increased permeability to sodium was completely abolished when the cells were pretreated with a specific inhibitor of anion transport (DIDS). Both bicarbonate‐induced sodmm influx and chloride exchange were linearly related to DIDS‐binding. Both transport processes were completely inhibited by the binding of 1.1X 106 DIDS molecules per cell. The presence of bicarbonate and/or pre‐treatment of the cells with DIDS did not change the permeability of the erythrocyte membrane to K+, Rb+, and Cs+ to any significant extent. The experimental findings support the hypothesis that Li+ and Na+, but not K+, Rb+, and Cs+ form monovalent negatively charged ion pairs with CO3‐, which traverse the membrane through the anion exchange system.
Firing behaviour in stochastic nerve membrane models with different pore densities
Authors: SKAUGEN ERIK
Published: December 2008

A stochastic nerve membrane model with a two‐state pore system was investigated by computer simulation in the uniform (space‐clamped) case. The model was based upon the Hodgkin‐Huxley equations for the giant axon in squid, but where both the maximal membrane conductances and the rate constants were changed systematically. This was done in order to simulate nerve membranes of small axons, where both of these parameters are smaller than in squid. It was found that the effects upon the firing behaviour due to a finite number of pores were not greatly affected by changes in these parameters. When the specific injected current was calculated relative to the maximal membrane conductances, the threshold for firing was increased somewhat, and the frequency‐current relationship became slightly more linear when the maximal conductances (or pore density) were decreased, or the rate constants increased. In the discussion it is shown how the results obtained could be applied qualitatively to the firing behaviour of nerve cells, and that firing in small nerve cells should be significantly influenced by the stochastic effects of a finite number of pores. Gating currents were also discussed, and their effects were found to be insignificant in small nerve cells.
Time course of adaptation to low intensity training in sedentary men: dissociation of central and local effects
Authors: ÖRLANDER JAN , KIESSLING KARL‐HEINZ , EKBLOM BJÖRN
Published: December 2008

The oxygen transporting capacity and the metabolic capacity of the vastus lateralis muscle were followed in parallel in 9 sedentary, overweighted men during a low intensity training program. Measurements were made at 0, 3, 6, 9, 12 and 30 weeks. Maximal oxygen uptake increased in an approximately linear fashion during the first 12 weeks (11%), but decreased a little (3%) during the following 18 weeks. Mean body weight decreased 8% (7.4 kg) during the training. The distribution of muscle fibre types, including the subgroups of type II fibres, did not change. Muscle enzyme activities remained essentially unchanged during the training. It was concluded that “central” och “local” adaptation need not occur in parallel, and that the leg oxygen utilization capacity probably does not limit the whole body's maximal oxygen uptake.
Comparison of mucus collecting methods in fish olfaction
Authors: STABELL OLE B. , SELSET ROLF
Published: December 2008

A new method for collecting non‐contaminated skin mucus from fishes is introduced. The method is compared with a “customary” method by gel filtration, analysis of free amino acids, and determination of dry weight. Skin mucus collected by the “customary” method is shown to be contaminated by intestinal juice. The role of skin mucus as a source of fish odorants affecting fish behaviour is discussed in the light of the above findings.
Barrier mechanisms for neurotransmitter monoamines in the choroid plexus
Authors: LINDVALL M. , HARDEBO J. E. , OWMAN CH.
Published: December 2008

Studies were performed on choroid plexuses from mouse and rat. The plexus tissue, sympathectomized to avoid interference from adrenergic nerves, is able to accumulate L‐DOPA as well as NA and 5‐HT against a concentration gradient. Within the plexus tissue these compounds are metabolized by aromaticl‐amino acid decarboxylase, MAO and COMT, whose activities were determined radiometrically. On the basis of this and the fate of systemically administeredl‐DOPA and DA studied by fluorescence histochemistry it is suggested that the epithelium of the choroid plexus provides not only a structural but also an enzymatic barrier for transmitter amines. The enzymatic barrier for amine precursors is considerably less sufficient at this blood‐CSF interphase. The trapping of monoamines resembles the enzymatic barrier present in the endothelial cells and pericytes at the microvascular level of the blood‐brain interphase.
Adrenal medullary control of muscular and hepatic glycogenolysis and of pancreatic hormonal secretion in exercising rats
Authors: RICHTER E. A. , GALBO H. , SONNE B. , HOLST J. J. , CHRISTENSEN N. J.
Published: December 2008

We have previously shown that in exercising adrenodemedullated rats chemically sympathectomized with 6‐hydroxydopamine, the muscular and hepatic glycogen breakdown were diminished and the plasma glucagon and insulin concentrations were lower and higher, respectively, than in controls. To elucidate whether these effects could be ascribed selectively to the lack of the adrenal medulla or to the lack of the sympathetic nerve endings, rats were either surgically adrenodemedullated, chemically sympathectomized with 6‐hydroxydopamine, both adrenodemedullated and chemically sympathectomized, or sham‐treated. 3 weeks after adrenodemedullation a liver biopsy and cardiac blood was obtained. Subsequently the rats either rested or swam with a tail weight for 100 min. Immediately afterwards, cardiac blood was drawn and liver and muscle tissue were collected. The effects of combined adrenodemedullation and chemical sympathectomy were found to be due to the lack of the adrenal medulla. Furthermore, in adrenodemedullated rats, compared to controls, the concentration of norepinephrine in plasma was markedly reduced during exercise. The total activity (a+b) of glycogen phosphorylase in muscle was reduced 20% by adrenodemedullation. The findings indicate that during prolonged exercise adrenomedullary hormones enhance muscular and hepatic glycogenolysis as well as glucagon secretion, but inhibit insulin secretion in the rat. Furthermore, in contrast to the findings in man, in the rat a major part of the circulating norepinephrine is of adrenomedullary origin during exercise.
Ultrastructure of neurosecretosomes sedimented in the nuclear fraction from the posterior pituitary of the rat
Authors: KANERVA L. , TISSARI A. H. , RECHARDT L. , HERVONEN A.
Published: December 2008

Subcellular fractions of the posterior pituitary of the rat were isolated by differential and density gradient centrifugation, and microsamples prepared for electron microscopy by KMnO4 or glutaraldehyde‐OsO4 fixation. The nuclear fraction, P1 (1000 g × 7 min), was the main neurosecretosome (NSS) fraction and contained nuclei and mitochondria in addition to NSS (60%). The crude mitochondrial fraction, P2 (10000 g × 20 min), contained free mitochondria (70%), NSS, unidentified membrane particles, fat droplets derived from pituicytes, neurosecretory granules (NSG) and synaptosomes, identified by the presence of synaptic membrane thickenings. Fraction P3 (32 900 g × 20 min) contained mainly free NSG, while fraction P4 (118000 g × 30 min) had a high microsome content.
Brain extracellular space during spreading depression and ischemia
Authors: HANSEN ANKER JON , OLSEN CARL ERIK
Published: December 2008

The change of extracellular space volume of rat brain cortex during ischemia and cortical spreading depression, CSD (Leāo4) was evaluated by a new method. The cortical surface was imgated with isotonic CSF containing the extracellular markers 50 mM cholin or 50 mM trimethyltris(hydroxymethyl)methyl ammonium ion (N‐TRIS), and their extracellular concentrations were monitored by ion‐selective microelectrodes. When steady‐state for the concentration of these markers was attained, CSD evoked a reversible increase of the concentration of the markers, indicating shrinkage of the interstitial volume of distribution. During ischemia an initial slow rate of concentration increase was observed, followed a few minutes later by a rapid increase concomitant with the sharp rise in extracellular potassium concentration. During CSD and ischemia, the maximal increases of choline and N‐TRIS concentration reflected a shrinkage of the extracellular space amounting to about 50% of the initial volume.
Renal blood flow distribution during E. coli endotoxin shock in dog
Authors: KIRKEBØ A. , TYSSEBOTN I.
Published: December 2008

The effect of endotoxin on renal blood flow distribution was studied in anesthetized dogs. Renal blood flow was measured as hydrogen clearance by platinum electrodes placed in outer and in inner halves of cortex and by electromagnetic flowmeter. Intravenous injection of E. coli endotoxin, 3–5 mg/kg b. wt., promptly reduced arterial blood pressure (AP) and renal blood flow. After a transient increase for 45 min AP and renal blood flow declined to about 50% of the control 2½‐3 h after injection. The reduction in outer cortical blood flow (OCF) was not significantly different from the reduction in inner cortical blood flow (ICF). The hematocrit (Hct) increased from 40.1±3.8% to 54.6±8%, but mean renal vascular resistance did not change. Total plasma protein concentration was not significantly elevated. A marked local flow variability was observed in some periods during the phase of shock with declining AP and total renal blood flow at high Hct. Thus renal blood flow showed phasic changes, but the OCF/ICF ratio was not changed during endotoxin shock. Local blood flow instability was observed periodically at high Hct.
Functional properties of neurones in the parietal retroinsular cortex in awake monkey
Authors: LEINONEN LEA
Published: December 2008

The parietal retroinsular cortex of three, awake, behaving macaque monkeys was investigated using transdural microelectrode recording technique. All 73 cells identified responded to somatosensory stimuli. Most of the neurones (51) were activated by compression of the skin in an on, off or on‐off fashion; these cells were unresponsive to light touching or stroking of the skin. The rest of the cells responded to light touching, rotation of a joint or palpation of a muscle belly. All body parts were represented in this area. Of the cells 30% responded to stimulation of both sides of the body. The results indicate that the parietal retroinsular cortex participates in the analysis of skin compression. This information is used, i.e. in the control of manipulative movements and in discrimination of supported weights. It is possible that ablation of the area examined would impair these functions.
Capillary permeability in canine myocardium as determined by bolus injection, residue detection
Authors: HAUNSØ STIG , PAASKE WILLIAM P. , SEJRSEN PER , AMTORP OLE
Published: December 2008

Capillary permeability of51Cr‐EDTA in the canine myocardium was determined by applying: (A) the single injection, external registration method, and (B) the local tissue clearance method, to the intact dog heart of open‐chest anesthetized dogs. (A)51Cr‐EDTA was administered into the left anterior descending coronary artery as a bolus injection, and the response curve was recorded by external registration. The capillary diffusion capacity (the permeability‐surface area product) for51Cr‐EDTA amounted to 32.5 ml/100 g·min at a capillary extraction of 0.40 and a plasma flow of 73.3 ml/100 g·min. The diffusional permeability coefficient of51Cr‐EDTA was calculated to 1.08 × 10‐5cm/s, which indicates that the permeability of the capillaries in the myocardium for51Cr‐EDTA is similar to that of continuous capillaries in other tissues. (B)51Cr‐EDTA (3–100 μl) was injected at a depth of 5 mm into the myocardium of the left ventricular free wall and the residue curve was recorded. The capillary extraction, as determined by the tissue clearance method, was calculated to values 6 times smaller than determined with the single injection, residue detection method. This unreasonably low extraction was probably due to methodological errors inherent to the tissue clearance technique.