bluuebunny/crossref_metadata_2025 huggingface dataset:
Firing Behaviour of a Neurone Model Based on the Afterhyperpolarization Conductance Time Course and Algebraical Summation. Adaptation and Steady State Firing
Authors: Baldissera F. , Gustafsson B.
Published: December 2008

F. Baldissera and B. Gustafsson. Firing behaviour of a neurone model based on the afterhyperpolarization conductance time course and algebraical summation. Adaptation and steady state firing. Acta physiol. scand. 1974. 92. 27–47.

A preceding paper described the firing behaviour of a neurone model, in which the refractoriness was solely governed by a K conductance process similar to that underlying the afterhyperpolarization in the cat's a‐motoneurones (Baldissera and Gustafsson 1974 b). The present paper describes the firing behaviour of the same model implemented with algebraical summation of the consecutive AHP conductance. For the initial intervals after the onset of constant current the model is well simulating the successive changes in the frequency‐current (f/i) relations and the interspike voltage trajectories found in real motoneurones. The steady state f/i relation of the model can also display an upward deviation from linearity at higher current intensities, i.e. a ‘primary’ and a ‘secondary’ range of firing as described for real motoneurones (Kernell 1965 c). The results are discussed in relation to the terminology describing firing behaviour in motoneurones and to various hypotheses on firing control. It is concluded that the AHP conductance is the decisive factor for determining the f/i relations as well as the interspike voltage trajectories in motoneurones.
Excitation of Intradental Sensory Units by Pharmacological Agents
Authors: Oloart Leif
Published: December 2008

Recordings were made from intradental sensory nerves in the tooth of the cat. Local application of bradykinin and histamine failed to induce impulse activity, even when applied to the exposed pulp, whereas 5‐hydroxytryptamine produced bursts of impulses with short latency, lasting a few seconds. Application of compound 48/80 induced an increase in impulse activity after a delay of some minutes and this activity persisted for about 2 h irrespective of whether the agent was removed or not. The impulse frequency decreased promptly when the temperature was raised and recovered when the temperature was lowered again. Pre‐treatment with polyphloretin phosphate (PPP) inhibited the excitatory action of compound 48/80. The threshold of excitation to cold stimulation was lowered after introduction of compound 48/80. Since the principal action of compound 48/80 is to release endogenous substances from mast cells the present findings may indicate that the increase in impulse activity is secondary to a release of biogenic substances. However, at present a direct action of compound 48/80 can not be excluded.
Incorporation of Imipramine into Isolated Rat Peritoneal Mast Cells in Vitro
Authors: Gripenberg J.
Published: December 2008

The incorporation of imipramine into isolated rat peritoneal mast cells was fluorometrically studiedin vitro.The binding of imipramine was characterized by the following features: 1. it took place in two phases, the first of which was very rapid, 2. it increased with increasing exogenous concentration in a sigmoidal fashion, 3. it increased with increasing exogenous pH, 4. it was dependent on neither temperature nor calcium ions in the medium nor did the binding occur specifically to mast cells but also to leucocytes, 5. it was reduced by several imipramine derivatives, tricyclic antidepressants and 5‐hydroxytryptamine at high concentrations, 6. about 40 % of the cell‐bound drug was easily washed out; the remaining 60 % represented a level approached after prolonged washing and seemed to be fairly tightly bound, 7. the subcellular location of imipramine in mast cells was different from that of 5‐hydroxytryptamine, indicating a nongranular binding of the drug. It is concluded that imipramine binds to mast cells in a passive manner and is associated with the cell membrane where it seems to be bound to at least 2 different sites. At low concentrations imipramine is probably bound to sites specifically influencing the operativeness of the amine carrier. Higher concentrations of imipramine results in binding to nonspecific sites resulting in impairment of the structure and function of the cell membrane.
Parallel Activation of Dynamic Fusimotor Neurones and a Climbing Fibre System from the Cat Brain Stem. II. Effects from the Inferior Olivary Region
Authors: Jeneskog Torgny
Published: December 2008

Climbing fibre activity in the cerebellar paramedian lobule and hind limb dynamic fusimotor activation, caused by electrical stimulation in the medial parts of the medulla, were studied in halothane anesthetized cats. Three regions influencing dynamic fusimotor neurones were found. From one of these, corresponding to the nucleus reticularis gigantocellularis, descending activity proceeded in the contralateral ventrolateral funiculus. From the other two, corresponding to parts of the inferior olive and the pyramid respectively, the spinal pathways were located in the contralateral dorsolateral funiculus. The pathway from the olivary region seemed to be identical to a previously described dynamic facilitatory pathway activated in the rubral region. Climbing fibre activity in a hind limb zone of the paramedian lobule was evoked with short latency from caudal parts of the principal olive, but, probably transsynaptically, also from wider areas within the inferior olive. On stimulation in the red nucleus orthodromic responses were found in one region overlapping the nucleus reticularis gigantocellularis, and in another one, situated in the caudal parts of the principal olive. In this latter region, postsynaptic activity was recorded also from the DLF‐SOCP. Evidence for a convergence between this pathway and the one from the rubral region was obtained.
Release of Kallikrein from Isolated Cellular Organelles of the Rat Submandibular Salivary Gland
Authors: Gautvik K. M. , Kriz M.
Published: December 2008

Subcellular organelles which contained kallikrein were isolated from homogenates of rat submandibular salivary glands by sucrose density gradient centrifugation. Kallikrein activity and BAEE‐esterase activity were localized to the same subcellular fractions. The BAEE‐esterase containing organelles lysed easily in normoosmolar buffer solutions and liberated soluble enzyme. The spontaneous lysis of these organelles was reduced in hyperosmolar solutions. The presence of calcium (2.6–27 mM) stabilized the enzyme containing organelles, but magnesium (25 mM) and potassium (60 mM) had no such effect. Replacement of sodium with sucrose and removal of calcium, magnesium or potassium had also no effect on enzyme release.
Tactile Placing Reactions in Chronic Spinal Kittens
Authors: Forssberg H. , Grillner S. , Sjöström A.
Published: December 2008

Transection of the spinal cord at the level of Th 12 to L 1 was performed in 6–14 days old kittens. The kittens were kept for several months after the operation. During this period tactile stimuli applied to the dorsum of the hindpaw could evoke a flexion followed by an extension and a placing of the limb in a more rostral position. These reactions have been studied by recording the EMG activity and filming the movement. It is concluded that it must be regarded as tactile placing, which contrary to what has hitherto been assumed is not a reflex relayed in higher nervous structures, but rather a complex form of spinal reflex.
The Influence of Sympathetic Activity and Histamine on the Blood‐Tissue Exchange of Solutes in Canine Adipose Tissue
Authors: Linde By Birgitta , Chisolm Guy , Rosell Sune
Published: December 2008

By means of a single injection technique diffusion capacities for14C‐sucrose and3H‐polyethylene glycol (M.W. 800–1000) (PEG), expressed as the PS‐product of Renkin, were determined in dog subcutaneous adipose tissue.

Under resting conditions PS for sucrose and PEG were approximately 2 and 1 ml × min‐1× 100 g‐1respectively. During maximal vasodilatation induced by prostaglanclin E2(PGE2) and papaverine the PS‐products were approximately doubled. The effects of sympathetic nerve stimulation (1–6 Hz) and histamine on the diffusion capacities were compared with controls at the same blood flow. During sympathetic nerve stimulation PS for sucrose increased 15 % in spite of a vasoconstriction. When superimposed on a maximal vasodilatation sympathetic nerve stimulation induced increases in PS for sucrose of approximately 40%and in PS for PEG of about 20 %. Histamine increased PS for sucrose 40%in a dosedependent fashion compared with a vasodilatation of the same magnitude induced by papaverine or PGE2. The results indicate that sympathetic nerve stimulation causes an increase in vascular permeability for solutes in canine subcutaneous adipose tissue. Histamine seems to have the same effect.
Choroid Plexus Uptake of Acetylcholine
Authors: Winbladh B.
Published: December 2008

Acetylcholine (Ach) is accumulated by rabbit choroid plexa in vitro by active transport. The transport system seems to be identical to that for choline (Ch), and has a higher capacity: Calculated maximal speed varied between 10 and 60 mmol × min ‐1× kg‐1 wet weight. The choroid plexa contained a significant cholinesterase (ChE) activity which seemed to be localized intravascularly. ACh was not metabolized by the tissue i.e. intravascular concentrations of accumulated ACh were low. The cholinesterase inhibitor (ChEI) physostigmine inhibited ACh and Ch uptake, while the two ChEI:s soman and sarin stimulated the uptake of both ACh and Ch. The relative stimulation of the ACh uptake by soman increased with increasing ACh concentration in the incubation medium. The stimulation of ACh (10‐5 M) uptake was not significantly different at soman concentrations ranging from 10‐3 to 10 ‐6 M. Soman did not enhance the release of ACh from tissue preincubated at 10‐5 or 10‐3 M ACh for 15 min. The results are discussed in relation to ACh and Ch transport in brain slices. Further, possible localizations of the transport mechanism are briefly discussed.
Comparison between Effects of Cyclic AMP, Dibutyryl Cyclic AMP and Luteinizing Hormone on Ovarian Glycolysis
Authors: Herlitz By H. , Hamberger L. , Ahrén K.
Published: December 2008

Prepubertal rat ovaries were incubated in medium containing 5.5 mM glucose and various concentrations of cyclic AMP (cAMP) and dibutyryl cyclic AMP (dbcAMP). Glucose uptake and lactic acid production were stimulated in presence of 5 mM cAMP. The effect was less pronounced with higher concentrations, and 25 mM cAMP inhibited ovarian glycolysis compared to control ovaries. A biphasic effect was also obtained with dbcAMP: a dose‐dependent increase with lower concentrations (0.1–5 mM) and smaller effects with higher concentrations. Luteinizing hormone (LH) stimulates ovarian glycolysis with a linear dose‐response relationship over an extremely wide range of concentrations (Hamberger and Ahren 1967). The stimulatory actions of dbcAMP and LH on ovarian glycolysis were augmented by low concentrations of aminophylline (0.5‐1 mM). No additive effects were seen when LH and dbcAMP were used together in maximal stimulatory concentrations. LH, cAMP and dbcAMP were also compared as to their lipolytic actions on the ovary. Lipolysis as judged by glycerol release was markedly enhanced by dbcAMP while the two other substances had only marginal effects. When bovine serum albumin (acceptor for fatty acids) was present in the medium, the dose‐response curve of the effect of dbcAMP on ovarian glycolysis was dramatically changed, indicating an interaction between the lipolytic and the glycolytic effects of this compound.
Effects of Gonadotrophins, Dibutyryl Cyclic AMP and Prostaglanclin E2 on Amino Acid Transport and Glycolysis in Isolated Rat Corpora Lutea
Authors: Herlitz By Hans
Published: December 2008

Corpora lutea (CL) were isolated by free hand dissection from ovaries of 34–39 day‐old Sprague‐Dawley rats injected with 10 IU Pregnant Mare's Serum gonadotropin (PMSG) when 30 days old leacling to ovulation in the morning of day 33. Injection of luteinizing hormone (LH) to rats 2 h before removal of the ovaries stimulated the in vitro uptake of the non‐utilizable amino acids, a‐aminoisobutyric acid (AIB‐14C) and 1‐amino‐cyclopentane‐carboxylic acid (cycloleucine‐3H) by 3‐day‐old CL during a subsequent incubation in Krebs bicarbonate buffer. Prolactin and FSH were without effects. Addition of LH directly to the incubation medium did not stimulate amino acid uptake of the isolated CL, while addition of dibutyryl cyclic AMP (dbcAMP) enhanced this uptake. Glycolysis was estimated by determination of lactic acid accumulation in die incubation medium. When LH was injected to the animals 2 h before sacrifice, lactic acid production of 3‐day‐old CL was stimulated during a subsequent incubation period. Addition of LH in vitro caused a slight increase in the rate of glycolysis, and dbcAMP and prostaglanclin E2 (PGE2) also exhibited stimulatory effects on lactic acid production by the incubated CL. In a few experiments rats with 7‐day‐oId CL were given injections of LH. While amino acid uptake was not stimulated in these old CL, LH did enhance the rate of glycolysis in these CL.
Effects of Repetitive Stimulation on Membrane Potentials and Twitch in Human and Rat Intercostal Muscle Fibres
Authors: Hanson By Jerker
Published: December 2008

Membrane potentials of human and rat external intercostal muscles have been studied in vitro at body temperature, and contraction curves at both body and room temperature. Histochemical staining of the entire preparation used in the experiment was performed. The resting membrane potential was on the average somewhat higher in human than in rat intercostal muscle fibres. The mean duration of the spike was 1.50 ms for the human fibres and 0.89 ms for the rat fibres. The mean contraction times were 79 and 11 ms, respectively. In the randomly taken human muscle fibre bundles the contraction times and the half‐relaxation times tended to be longer in preparations with many type I fibres (low ATPase activity) than in those with the same amount of type I and type II (high ATPase activity) fibres. Repetitive stimulation of human muscle fibres had very small effects. In rat muscles stimulation at 10 Hz for 30 s caused a marked increase in the twitch amplitude, an increase in the spike duration and in the amplitude of the early negative after‐potential. In both preparations the contraction speed was slower at room temperature than at body temperature. In rat intercostal muscles the twitch amplitude was higher at room temperature than at body temperature; in the human muscles it was the same. The twitch: tetanus ratio at body temperature was higher in human than in rat intercostal muscles.
Decremental Conduction, in Normal Human Nerves Subjected to Ischemia?
Authors: Nielsen By V. Kamp , Kardel T.
Published: December 2008

The effect of ischemia on the maximal orthodromic sensory and motor nerve conduction was studied in the digit 1‐elbow segment of the median nerve in 24 normal subjects. Action potentials were recorded at 2, 3 or 4 sites along the nerve. The latency of the potentials increased as a function of the duration of ischemia and of the distance from the point of stimulation. The earliest indication of an impaired nerve function was a decrease in the sensory action potential amplitude. During ischemia the length of the nerve segment, through which the potential was propagated, gradually became shortened. This was seen in sensory as well as in motor nerves. The sensory threshold to electrical stimuli (digit 3) had a two‐phasic course: During 15 min of ischemia it was almost stationary despite a severe reduction of the conduction velocity and of the potential amplitude. Then a rapid increase took place, coincicling with the extinction of the potential recorded at the elbow just below the occlucling cuff. The conduction parameters were normalized shortly after reestablishment of the circulation in the arm. The results indicate that action potentials become conducted with decrement during ischemia.
Choline Acetyltransferase Activity in Rat Salivary Glands Enlarged by Isoprenaline Treatment
Authors: EKSTRÖM JÖRGEN
Published: December 2008

Certain procedures have earlier been found to cause the weight of the rat parotid gland to vary. After these procedures the choline acetyltransferase activity in the gland was also found to have changed in the same direction as the weight. This might suggest that variations in the gland mass in itself could influence the choline acetyltransferase activity. However, the present study shows that this does not seem to be the case, since a marked enlargement of the parotid gland, induced by isoprenaline treatment, can occur without being accompanied by any increase in the activity of this enzyme.
Effect of Atropine on Hypoglycemic Release of Gastrin in Man
Authors: Stadil F. , Malmstrøm J. , Rehfeld J. F. , Miyata M.
Published: December 2008

Hypoglycemic release of gastrin has been supposed solely to be due to vagal release. In this report the atropine resistance of the gastrin response to insulin was examined. 9 normal subjects were studied twice. 0.2 IU of insulin/kg i.v. was injected in each study, but in one atropine (30 μg/kg i.m.) was injected prior to insulin. Serum gastrin concentrations were measured by radioimmunoassay. Blood glucose concentrations did not differ in the two studies. Atropine almost abolished gastric output of acid. Gastrin concentrations rose after insulin and slightly more after atropinization. In four of the subjects a second late gastrin increase was observed after atropine. It is concluded that in man a major part of the hypoglycemic release of gastrin is independent on a cholinergic mechanism.
The Acid‐Catalyzed Formaldehyde‐Induced Fluorescence in the Hypophysis of the Human Fetus
Authors: Partanen Seppo
Published: December 2008

The acid‐catalyzed formaldehyde‐induced fluorescence (FIF) was studied in Epon embedded hypophyses of human fetuses aged between 12 and 19 weeks. To test the validity of Epon embedded sections in glacial acetic acid induction of FIF, sections of the hypophyses of adult rats were used. It was observed that Epon embedded sections were suitable. After acidification a large number of fluorescent cells was observed in the pars distalis of the hypophyses of human fetuses: new fluorescent cells appeared and the fluorescence intensity in the cells, already fluorescent after the ordinary FIF, increased. On the basis of this increase the fluor‐ogenic substance is probably the same as in other mammalsi.e.a peptide with NH2‐terminal tryptophan. This peptide has been proposed to be somehow involved in the storage and/or release of protein hormones. The fluorescence is probably a sign of maturity of secretory granules in large number of PAS‐positive cells in the pars distalis of the fetal hypophysis. First fluorescence after acidification was observed in the cells of the pars intermedia at the age of 15 weeks. At the age of 19 weeks most cells exhibited yellow fluorescence. The fluorescence intensity was weaker than in the cells of the pars distalis. Thus the pars intermedia of man does not differ in this respect from that of other mammals.
Capillary Permeability to Glucose and Raffinose Studied with Single‐Injection Technique
Authors: ÅBerg Bo
Published: December 2008

In a series of single‐injection experiments on continuously weighed isolated cats' hind legs, the extractions of glucose and raffinose in pair were calculated. The extraction was calculated by using albumin tagged with Evans' blue as a reference. The reference was found to exchange with the tissue, and after a correction for this loss from the bolus, the extraction ratio raffinose over glucose ranged between 0.681–0.764. This was slightly above the ratio of the free diffusion coefficients (D38raffinose/D38glucose = 0.645) and much above the ratio of the corresponding restricted diffusion coefficients (0.42–0.44 assuming an average pore radius of 4 nm).
The Turnover of 85Zn in Rats Fed a Zinc‐Deficient Diet
Authors: Bergman Bo , Wing Kenneth R.
Published: December 2008

The fresh weight zinc concentration in spleen is unchanged, the concentrations in serum, kidney, pancreas, liver and heart are reduced moderately and those in incisors and four bone samples are reduced markedly in rats fed a zinc‐deficient diet (7.2 fig Zn/g) for six weeks compared to those in rats pair‐fed the same diet and given a 200 fig zinc supplement daily. The ash weight zinc concentrations in mineralized tissue samples from both groups decrease rapidly and, after three weeks on the diet, assume relatively stable levels. The retention of 85Zn in the serum, heart and viscera is higher in rats not given the supplement. The pattern is consistent with decreased turnover of zinc due to reduced intake and excretion. The 65Zn retention data from the bones and teeth were analyzed using the Bauer, Carlsson, Lindquist equation. Reduced zinc intake causes a decrease in bones of the rate at which zinc is “accreted”, most likely as a result of decreased accretion of bone as well as decreased availability of zinc. The slowly exchanging zinc in incisors and cortical bone is markedly reduced while the rapidly exchanging zinc in bones is less affected.
Intra‐ and Extraperitoneal Pressures
Authors: Bjerle Per , Sandström Bo
Published: December 2008

In order to determine the reliability of various methods of recording intraabdominal pressure, seven healthy women were investigated in connection with routine laparoscopy. Intraabdominal pressure was measured through a trochar in the gas‐filled abdomen. Intragastric pressure was measured with an air‐filled balloon, perivesical pressure through a catheter in the space of Retzius and intravesical pressure through a Foley catheter introduced via the urethra. With the urinary bladder empty, intraabdominal, perivesical and intravesical pressures did not differ. The intragastric pressure was somewhat higher than the other three pressures, possibly due to hydrostatic pressure effects from the viscera. In conclusion, if the bladder is empty, perivesical as well as intravesical pressure registration appears to be a useful method of fairly closely following the intraabdominal pressure in the supine position without perforating the peritoneum.
Transmural Pressure of the Urinary Bladder Wall
Authors: Bjerle Per
Published: December 2008

Intragastric, perivesical and intravesical pressures were registered during slow filling of the urinary bladder in nine healthy men in the supine and sitting positions. Intragastric pressure was fairly constant in both positions, but intravesical pressure rose and there was also a slight rise of perivesical pressure. In both body positions transmural pressure, i.e. the pressure difference between the inside and the outside of the tbladder, rose during bladder filling. In both body positions at bladder volumes ^ 300 ml, in this material, transmural pressure, determined as the difference between intravesical and perivesical pressures, did not differ statistically significantly from transmural pressure calculated as the difference of intravesical and intragastric pressures minus a hydrostatic component. At maximal bladder volumes transmural pressure determined in the first way was statistically significantly lower than that calculated in the second way. In the supine position the transmural pressure at bladder volume 300 ml, calculated as the difference of intravesical and perivesical pressures, was lower than in the upright position.
Tension, Stress and Modulus of Elasticity of the Urinary Bladder Wall
Authors: Bjerle Per
Published: December 2008

Transmural bladder pressure, i.e. the difference between the intravesical and perivesical pressures, was continuously registered during slow filling of the bladder in nine healthy men. On the basis of the pressure thus obtained, the surface tension of the bladder was calculated. From the latter and from the assumed thickness of the bladder wall, the normal stress in the wall and a differential modulus of elasticity were calculated. The surface tension, the normal stress and the differential modulus of elasticity increased markedly as the radius of the bladder increased. The logarithm of the maximal differential modulus of elasticity registered was linearly correlated to the bladder radius. This relationship makes it possible to predict in normal subjects the differential modulus of elasticity from the bladder radius and thereby obtain information regarding possible abnormalities in the mechanical properties of the bladder wall.
Inhibitory Effect of Prostaglandins on Isosmotic Fluid Transport by Rabbit Gall‐Bladder In Vitro, and its Modification by Blockade of Endogenous PGE‐Biosynthesis with Indomethacin
Authors: Leyssac P. P. , Bukhave K. , Frederiksen O.
Published: December 2008

In the presence of indomethacin serosal application of PGEi and PGE2 caused significant inhibition of net isosmotic fluid transport by the gall‐bladder with maximum effect (50%inhibition) at 0.5ftgPGE/ml. Mucosal application was much less effective. PGF2a was about 100 times less potent than PGE. In the absence of indomethacin the sensitivity to low concentrations of PGEi was about 10 times less than in the presence of this drug (p < 0.001). Maximum effective doses of PGEi depressed the unidirectional Na+‐efflux about 35%and the Na+‐influx about 20%.Transepithelial potential difference and ohmic resistance remained unchanged. It is concluded that PGE inhibits isosmotic fluid transport by an effect mainly on the active component of the transfer process. In the absence of indomethacin endogenous PGE2 (but not PGEi) was released to both serosal and mucosal medium. Net release to mucosal medium was 35–600 pg.h‐1.mg dry weight‐1; release was higher to the serosal medium. Mucosal concentrations of 0.2–4.5 ng PGEa/ml were independent of the serosal concentration, which did not exceed 0.8 ng/ml under the present conditions. The data suggest that mucosal PGEs‐release originates, in part at least, from the epithelial cells. Indomethacin (10 μg/ml) blocked almost completely thein vitroPGE‐biosynthesis.
Increased Inulin Absorption from the Gat Stomach Exposed to Acetylsalicylic Acid
Authors: Flemström Gunnar , Marsden N. V. B.
Published: December 2008

Polydisperse14C‐inulin was absorbed from the stomach of the cat when 15 mM acetylsalicylic acid, mainly in the unionized form, in isotonic NaCl solution, was also present in the lumen. The absorbed inulin was rapidly excreted and accumulated in the urine in sufficient quantities for molecular weight distribution analysis. The latter showed that about 95 percent of the urinary inulin had a molecular weight greater than 2000 and that only moderate molecular sieving of the instilled inulin (weight average molecular weight 5200) occurred. This means very probably that larger molecular species than tested here could be absorbed from the stomach. The instillation of14C‐inulin in acetylsalicylic acid‐free isotonic NaCl, however, also resulted in a smaller but significant inulin absorption. The latter was further considerably reduced if the inulin was not added together with the isotonic saline, but later (20 min) in a small liquid volume. This suggests that mere distension of the stomach causes a temporary increase of the permeability which, however, is much smaller than that after acetylsalicylic acid. It may be relevant that acetylsalicylic acid was found here to increase gastric absorption of saccharide molecules of a size earlier reported to be sufficiently large to evoke immune reactions.
Autoradiographic ‐ Histochemical Demonstration of Tyrosinase Activity in Melanin‐forming Tissues of Mammals
Authors: Lindquist Nils Gunnar
Published: December 2008

The tyrosinase activity in melanin‐forming tissues was investigated in a series of rats (6 days to 1 year old), one cat 30 days old, and one 4 month old human fetus. The technique used was an autoradiographic‐histochemical method, utilizing the HC‐labelled melanin precursor tyrosine as a substrate. A high accumulation was found in the iris and ciliary body in the young pigmented animals and also in the human fetus. In addition a rather high activity was observed in the choroid of these specimens. When sodium diethyldithiocarbamate (10‐2 M), a tyrosinase inhibitor, was added to the incubation solution no specific uptake was seen. The level in the corresponding tissues of the albino rats was low. In the 1 year old pigmented rat a significant activity was still seen in the uveal tract and was very pronounced in the iris–indicating that the melanin formation in the eye may continue even into the adult stage. High tyrosinase activity was also found in other melanin‐forming tissues such as those in the inner ear and the hair follicles of the human fetus, and in the hair follicles, skin, and meninges of the young pigmented rats.
Apparent Efficiency and Storage of Elastic Energy in Human Muscles during Exercise
Authors: Asmussen Erling , Bonde‐Petersen Flemming
Published: December 2008

3 subjects ran on the treadmill (10 km/h) against varying horizontal impeding forces. One subject was further studied during the same kind of walking and bicycling on the treadmill, and during work consisting in lowering and lifting the body by flexing and extending the legs from a standing or sitting position at varying frequencies, with or without rebound in the deepest position. Workpower (W kcal/min), and the corresponding steady state metabolic rate (E kcal/min, Douglas bag method) were measured. Apparent efficiency (N) was calculated as Δẁ/ΔÈ× 100 %. During load running N was 53.8, 37.6 and 41.2 %, respectively, in the 3 subjects. In the subject more extensively studied N was: running 53.8, walking 32.3, bicycling 25.1, knee‐flexions (deep or half) with rebound 39.4 or 41.0, without rebound 26.1 or 21.9 %. These variations in N % were explained in accordance with the possibilities for re‐using the energy, absorbed and stored in the muscles as elastic energy during a phase of negative exercise, in a subsequent phase of positive exercise. The condition of this is that the positive phase follows immediately after the negative. A calculation showed that during running 35–53 % of the energy absorbed during the negative phase was re‐used. Corresponding figures for walking and rebounding knee‐extensions were 23 % and 34 %, respectively, while in bicycling and knee‐extensions without rebound all of the negative work degenerated into heat.
Catecholamine Output of Males and Females over a One‐Year Period
Authors: Johansson Gunn , Post Birgitta
Published: December 2008

Urine samples were collected under constant conditions once every fourth week over 1 year. The subjects, 13 male and 11 female office employees and workers in industry, participated in the study during their ordinary daily work routine. Large interindividual differences in the rate of catecholamine excretion were obtained, whereas most subject showed a high intra‐individual constancy of excretion. Neither variations over the year, nor differences between men and women in the excretion of adrenaline or noradrenaline, were statistically significant. However, the women differed from the men in that their adrenaline excretion was not significantly higher in a test session than during daily work routine.
Circulatory Responses to Stimulation of the Carotid Body Chemoreceptors in the Cat
Authors: Little Rod , ÖBerg Bengt
Published: December 2008

Cardiovascular responses to carotid body chemoreceptor stimulation were followed in the ‘curarized’, vagotomized, artificially ventilated cat. Stimulation of the chemoreceptors by perfusion of the carotid sinus regions with venous blood induced a reflex vasoconstriction in skeletal muscle, kidney, intestine and skin, and, in most cases, an increased heart rate. A comparison of the chemoreceptor reflex responses with those obtained by direct electrical stimulation of the regional vasomotor fibres indicated that in chemoreceptor reflexes the vasomotor fibre activity increased to the same extent in skeletal muscle and intestinal resistance vessels and, probably, in the ‘nutritional’ skin vessels but to a smaller extent in the renal vessels and the skeletal muscle capacitancc vessels. The renal vessels and the muscle capacitance vessels seemed, however, to respond more during chemoreceptor stimulation than when the baroreceptors were unloaded, indicating that an excitation of the bul bar vasomotor centre is more effective than the withdrawal of an inhibitory restraint in activating the vasomotor fibres to these vascular sections.
Changes in the Fetal Heart Rate and ECG during Hypoxia
Authors: Rosén K. G. , Kjellmer I.
Published: December 2008

Previous reports on the fetal hypoxic bradycardia in animals have indicated, that there is a vagal influence, especially when asphyxia is induced by umbilical cord occlusion. In the present study hypoxia was induced oia the mother, thus keeping the fetal circulation intact. The experiments were conducted on mature fetuses of three different species, namely 20 guinea‐pig, 3 cat and 3 lamb fetuses. The ECG was recorded continuously and used for measuring the fetal heart rate. The vagal influence on the fetal hypoxic bradycardia was tested by comparing the time for the onset of the bradycardia with or without vapl activity. There was no indication of any vagal component in the fetal hypoxic bradycardia, which is therefore to be regarded rather as a sign of myocardial hypoxia and failing fetal circulation. The ECG recordings showed that the fetal bradycardia initially is an AV‐block, type II, and that there are progressive changes in the S‐T interval as an early sign of hypoxia.
Conductance Recording of Ionic Outflow from Frog Skin Glands during Nerve Stimulation
Authors: Lang L. , Sjoberg E. , Skoglund C. R.
Published: December 2008

A method for continuous recording of the ionic efflux from frog skin glands has been developed which under given experimental conditions provides a convenient index on glandular secretion. A nerve skin preparation from the calf is mounted so that the outside of the skin forms the bottom of a small test compartment with distilled water while the corium side is bathing in Ringer's solution. After determination of the adequate nerve stimulus parameters for discernible gland secretion to occur, the skin nerve was stimulated at 10 Hz during varying periods and chemical control analyses performed of the changes in ionic content of the test compartment solution. The main ionic outflow consisted of Na+ and Cl‐ in equal amounts, the outflow of other ions during stimulation being negligible. The concomitant conductance changes were measured as variations of absorption in a high‐frequency field applied to a conductance probe placed in the test chamber. Determinations of the NaCl outflow based on the conductance changes were in good agreement with the values obtained by chemical analysis. The continuous conductance recordings proved to give approximative information of the quantities and time relations of the glandular secretion, allowing a direct comparison with, e.g., skin potential changes.
Aspects of the Central Integration of Arterial Baroreceptor and Cardiac Ventricular Receptor Reflexes in the Cat
Authors: Little Rod , Wennergren Göran , ÖBerg Bengt
Published: December 2008

The possible central integrative mechanisms, responsible for the earlier reported, differentiated reflex engagement of the renal and muscle vessels and the heart from cardiac ventricular receptors and arterial baroreceptors, respectively, were analyzed in atropinized cats. The reflex renal vessel, muscle vessel and heart rate responses, expressed as per cent of maximum, to graded activations of arterial baroreceptors (sinus pressure variations) and stimulations of ventricular receptor afferents in the cardiac nerve were systematically compared. Cardiac nerve stimulation with low frequencies was found to elicit more pronounced reflex renal vessel responses than muscle vessel and heart rate responses. In contrast, elevations of sinus pressure induced equally pronounced renal and muscle vessel responses. High frequency cardiac nerve stimulation elicited maximal reflex renal vessel responses, but only submaximal effects on muscle vessels and heart rate, while intense baroreceptor stimulation induced maximal reflex effector responses throughout. The submaximal heart rate response to cardiac nerve stimulation is probably due to a simultaneous activation of excitatory afferents. On the other hand, the less pronounced muscle than renal vessel responses when the cardiac nerve was stimulated probably reflect a relatively sparse innervation of muscle vasomotor neurons by ventricular receptor afferents, which seem instead to be preferentially oriented towards renal vasomotor and, possibly, cardiac motor neurons.
Measurement of Endometrial Blood Flow in Guinea‐pig Uterus by Clearance of Intraluminally Applied 133Xenon: Effects of Oophorectomy, Estrogen Treatment and Pregnancy
Authors: Einer‐Jensen N. , Edvinsson L. , Falck B. , Owman Ch. , Sjöberg N.‐O. , Walles B.
Published: December 2008

Endometrial blood flow (EBF) was studied atraumatically in guinea‐pigs by the 133xenon clearance technique. With the aid of an otoscope, a xenon‐saline solution was deposited via the vagina through a cannula into the uterine lumen. Radioactivity curves were obtained by a small external scintillation detector. Oophorectorny lowered total flow whereas this was markedly increased (also per unit weight) by estrogen treatment, alone or in combination with oophorectomy. During early pregnancy there was a tendency to increase in the flow, while the values (for the parietal decidua) were markedly reduced at later stages of pregnancy. In the fetus‐placenta unit (133xenon solution injected intra‐amniotically) the flow was three times higher than in the parietal decidua at this advanced stage of pregnancy.
Ionic Requirements for Rapid Axonal Transportin vitroin Frog Sciatic Nerves
Authors: Edström Anders
Published: December 2008

The effects of K+, Na+, hypo‐ and hypertonicity on the synthesis and fast axonal transport of3H‐leucine‐labelled protein were studiedin vitroin the frog sciatic system. The methodology used made it possible to discriminate between effects on synthesis and transport of protein. The preparation which consisted of the dorsal ganglia, the sciatic nerve and the gastrocnemius muscle was placed in an incubation chamber. The ganglia were incubated in standard Ringer containingSH‐leucine and the nerve was prefused with modified Ringer. Perfusion of the nerve for 17 h with K+‐free Ringer or Na+‐free Ringer did not affect the rapid axonal transport of3H‐leucine‐labelled material from the ganglia along the nerve towards a ligature in front of which it accumulated. Nor was the transport influenced by concentrations of K+up to 68.8 mM. In contrast concentrations exceeding 100 mM K+partially inhibited the transport. Inhibition by ouabain (0.1 mM) was not prevented by elevating K+to 30 mM. Deviation from isotonicity, towards a hypo‐ or a hypertonic medium, partially inhibited axonal transport. The transport inhibitory effects showed reversibility. Experimental conditions, which arrested the transport, were tested in separate experiments for effects on uptake of3H‐leucine into TCA‐soluble and insoluble ganglionic components. K+substituted for Na+, ouabain (0.1 mM) and hypotonic Ringer partially inhibited the amino acid uptake hut also subsequent steps in the incorporation process, whereas only the latter was inhibited by hypertonic Ringer. The results are discussed in relation to possible changes in energy metabolism.
The Excitatory Action of Acetylcholine on Intradental Sensory Units
Authors: Haegerstam Glenn , Olgart Leif , Edwall Lennart
Published: December 2008

In order to test the hypothesis that ACh mediates the transmission of pain stimuli from dentin to sensory intradental nerve endings the following experiments were performed.

Intradental nerve impulses were recorded by means of low impedance electrodes inserted in dentinal cavities in the tooth of the cat. An air blast proved to be an efficient physical stimulus to excite the intradental nerves. Local application of acetylcholine caused a similar response. This response to acetylcholine was followed by a transient blockage to repeated application. The response to acetylcholine could be blocked by d‐tubocurarine, atropine, succinylcholine and hexamethonium administered locally. In contrast, the response to physical stimuli (air blasts) could not be blocked by these drugs. Moreover, during the period of depression following acetylcholine the preparation responded to physical stimuli. These findings suggest that acetylcholine is not a mediator in the intradental pain transmission provoked by physical stimuli.
Cerebral Units Activated by Tactile Stimuli via a Ventral Spinal Pathway in Monkeys
Authors: Anderson Sven A. , Finger Stanley , Norrsell Ulf
Published: December 2008

Extracellular microelectrode recordings were made in the forelimb and/or hindlimb areas of the cerebral post‐central gyri of 7 monkeys before and/or after acute dorsal hemisections of the cervical or low thoracic spinal cord. The animals were anaesthetized with either pentobarbitone sodium or chloralose. Among the units which were encountered after the lesions were 114 which could be influenced from the periphery. 38 units discharged to light tactile stimulation of small receptive fields and had a topographical organization like that observed in the intact animal. The remaining 76 units could be activated by peripheral electrical stimulation and/or by tapping, squeezing or light pinching. No units were found which specifically were activated by noxious stimuli. The two groups of cortical units responded with latencies only slightly longer than those obtained in the intact preparation. In the light of previous findings these electrophysio‐logical data suggest that, unlike carnivora, primates may possess the ventral spinal somatosensory pathway traditionally postulated on the basis of neurological material.
Acid‐Base Changes and Excitation‐Contraction Coupling in Rabbit Myocardium. II. Effects on Resting Membrane Potential, Action Potential Characteristics and Propagation Velocity
Authors: Jóhannsson M. , Nilsson E.
Published: December 2008

The effects of changes in acid‐base parameters on the resting membrane potential, action potential characteristics and propagation velocity were studied in isolated rabbit papillary muscles. Lowering extracellular pH from 7.4 to 6.7 in a bathing solution buffered with 10 mM histidine did not alter the resting membrane potential or action potential characteristics but caused a slight reduction in propagation velocity. A parallel increase in HCO3 concentration (up to 47 mM) and Pco2 at a constant extracellular pH of 7.4 caused a substantial decrease in action potential duration but did not alter the resting membrane potential or propagation velocity. The decrease in action potential duration was caused by the increase in HCO3 concentration. Propionate (47 mM) caused a shortening of the action potential which was of the same magnitude as for HCO3 but methylsulfate (47 mM) did not have this effect. The possible influence of these changes on the inotropic state of the myocardium and the cellular mechanisms involved are discussed.
Effects of Myocardial Infarction on Adrenergic Nerves of the Rat Heart Muscle, a Histochemical Study
Authors: Ahonen A. , Härkönen M. , Juntunen J. , Kormano M. , Penttilä A.
Published: December 2008

The anterior branch of the left coronary artery of the rat heart was ligated and the effects of anoxia on adrenergic nerves were studied histochemically using formaldehyde‐induced fluorescence for localization of norepinephrine. Greenish catecholamine fluorescence was associated in the normal or infarcted myocardium only with adrenergic nerves. Constant but not prominent changes were seen in adrenergic nerve fibers 2 or 4 h after ligation of the coronary artery; the number of delicate adrenergic fibers was reduced and some diffusion of the histochemical reaction was seen in small areas of the infarcted myocardium. Strong effects of anoxia were seen 8 h or more after ligation of the coronary artery. These were characterized by a prominent diffusion of the histochemical reaction and gradual disappearance of adrenergic structures in 2 to 4 days of anoxia. During the healing phase the appearance of numerous adrenergic nerve fibers was closely connected with the ingrowth of a new vascular bed into the infarction area. The observations indicate that adrenergic nervous structures of the myocardium resist the effects of anoxia, which may indicate the viability of sympathetic nerves in the infarcted area during long periods of anoxia.
Control of the Neurotoxicity of 6‐Hydroxydopamine by Intraneuronal Noradrenaline in Rat Iris
Authors: Sachs Charlotte , Jonsson Gösta , Heikkila Richard , Cohen Gerald
Published: December 2008

In vitrostudies with the neurotoxic compounds 6‐hydroxydopamine (6‐OH‐DA) and 6‐aminodopamine (6‐A‐DA) showed that noradrenaline (NA) markedly inhibited the autooxidation of 6‐OH‐DA, but not of 6‐A‐DA.In vivostudies of the adrenergic nerves in rat iris showed that the neurotoxic potency of 6‐OH‐DA, but not 6‐A‐DA, was increased after NA depletion by α‐methyl‐p‐tyrosine methylester(H44/68). Neurotoxicity was evaluated by measuring the associated decrease in3H‐NA uptake. lntraocular injection of NA counteracted the degenerative action of 6‐OH‐DA in both untreated and H44168 pretreated rats. Intraocular NA did not interfere with the neurotoxicity of 6‐A‐DA. Additionally, octopamine did not affect the rate of autooxidation nor the neurotoxic potency of 6‐OH‐DA or 6‐A‐DA. Control experiments with3H‐6‐OH‐DA showed that the intraneuronal NA levels did not significantly affect the intraneuronal accumulation of 6‐OH‐DA. The parallelism between thein vitroresults on autooxidation andin vivodata on neurotoxicity makes it appear that the neurotoxic potency of 6‐OH‐DA and 6‐A‐DA is closely associated with their rates of autooxidation. The control of the degenerative action of 6‐OH‐DA by intraneuronal NA may be mediated via reaction of NA with radicals formed from oxygen during autooxidation of 6‐OH‐DA.
The Action of Dibutyryl Adenosine‐3‘:5’‐Cyclic Monophosphoric Acid and Theophylline on the Isolated Cat Parotid Gland
Authors: Fritz M. E. , Grampp W.
Published: December 2008

In the isolated cat parotid gland intraarterially applied dibutyryl cyclic AMP (db‐CAMP) (1.0 mM) produced a slow, but often maintained salivary flow. db‐CAMP was also able to potentiate secretion evoked by supramaximal doses of intraarterially applied acetylcholine. Similar secretory effects were obtained also after intraarterial application of theophylline (1.0 mM). The secretory responses due to db‐CAMP or theophylline were unaccompanied by measurable acinar membrane potential changes and stayed unchanged after cutting the parasympathetic innervation of the gland and after blocking both cholinergic and β‐adrenergic receptors with atropine (10‐‐7M), and with D‐(‐)‐N‐isopropyl‐p‐nitrophenol‐ethanol‐amine (INPEA) (10‐‐5M), respectively. The possibility of the existence of an acinar adenylate cyclase system functionally linked to the β‐adrenergic membrane receptor is discussed.