bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of the Supply of Oxygen on the Tensile Strength of Healing Skin Wound and Granulation Tissue
Authors: Kulonen E. , Niinikoski J. , Penttinen R.
Published: December 2008

Experimental granulomas were induced in rats with subcutaneously implanted viscose cellulose‐sponges. The rats were kept for 10 days in normobaric atmospheres containing 21, 35 or 70 °., (V/V) oxygen. After killing, the tensile strengths of the granulomas and skin wounds were measured. In granulomas the tensile strengths were: in 21 % O2 107.2±9.7 g (23 determinations), in 3.5 °., O2 190.2 ± 18.5 g (41), in 70 % O2 221.0±24.6 g (26) and in skin wounds 431.3±32.8 g (29). 534.0 ± 22.8 g (40) and 574.1 ±32.9 g (24), respectively. The analysis of variances confirmed that the variation between the groups is larger than within the groups (for the granulomas P<0.001 and for the skin wounds P<0.005).
The Effect of DOPA on the Spinal Cord 6. Half‐centre organization of interneurones transmitting effects from the flexor reflex afferents
Authors: Jankowska E. , Jukes M. G. M. , Lund S. , Lundberg A.
Published: December 2008

In unanaesthetized spinal cats a systematic microelectrode exploration has been made in the lumbosacral spinal cord in order to find interneurones that may transmit the late longlasting reflex effects that volleys in the FRA (flexor reflex afferents) evoke after an intravenous injection of DOPA. Interneurones that may transmit these late effects are found in the lateral part of Rexed's layer VII and three main types are identified: A) cells activated from the ipsilateral FRA and inhibited from the contralateral FRA, B) cells activated from the contralateral FRA and inhibited from the ipsilateral FRA, C) cells activated from both the ipsilateral and contralateral FRA. The receptive fields and other criteria employed suggest that type A and B transmit excitatory action to flexor and extensor motoneurones respectively, and type C depolatization to Ia afferent terminals. The functional organization of these pathways is discussed mainly in relation to the mechanisms responsible for the long latency and duration of the discharge.
Blood Flow, Oxygen Uptake and Lactate Production in the Forearm during Exercise Induced by Median Nerve Stimulation
Authors: Landin Sven , Wahren John
Published: December 2008

A technique is described for percutaneous stimulation of the median nerve and the induction of a standardized involuntary forearm exercise. The electrically induced exercise is compared with voluntary forearm exercise in 14 healthy subjects at work intensities of 4, 6 and 8 kpm/ min. Blood flow, oxygen uptake and lactate production were found to be higher for electrically induced exercise than for voluntary, especially when the duration of the stimulus was increased from 0.1 sec to 0.3 sec. The increases in these parameters in relation to work intensity were steeper for electrically induced exercise than for voluntary. The differences are partly attributed to the exercise induced by electrical stimulation having a larger component of energy expenditure in static work from the activation of muscles that do not participate in finger flexion.
Studies of Blood‐pressure Regulation
Authors: ÖBerg P. Å. , Sjöstrand U.
Published: December 2008

A method has been worked out by which one of the closed control circuits in the blood‐pressure‐regulating system in the dog can be reversibly interrupted for varying periods of time. Careful studies of the chemistry of the carotid‐sinus blood, using this method, as well as of other conditions described in the literature, make it probable that the chemoreceptor mechanism in the carotid‐sinus region and the C.N.S. remain unaffected in this connection. The method provides the pre‐requisite conditions for on‐line simulation of the regulatory properties of the carotid‐sinus reflex, as regards the baroreceptor function.
Effects of Increased Intracranial Pressure on Cerebral Blood Flow and on Cerebrospinal Fluid HCO3, pH, Lactate and Pyruvate in Dogs
Authors: Kjällouist Å. , Siesjö B. K. , Zwetnow N.
Published: December 2008

The cerebral perfusion pressure was reduced in dogs by infusing an artificial cerebrospinal fluid (CSF) into the cisterna magna, or by reducing the mean arterial pressure by means of arterial bleeding, and the effects of the reduced perfusion pressure on the CSF concentrations of lactate, pyruvate and bicarbonate were studied. Even relatively small reductions (25–40 mm Hg) of the cerebral perfusion pressure were found to be accompanied by an increased CSF lactate concentration and an increased lactate / pyruvate ratio, and by a decreased bicarbonate concentration, suggesting the appearance of a slight hypoxic lactacidosis in spite of a normal, or near‐normal flow in the autoregulation range. When the cerebral perfusion pressure was markedly, or repeatedly, reduced a longlasting and often very marked lactacidosis was seen in the CSF. With a moderate lactacidosis in the CSF there was a good agreement between the increase in the lactate, and the decrease in the bicarbonate concentration, but with a marked and longlasting lactacidosis the decrease in the bicarbonate concentration could exceed the lactate accumulated. The possible coupling between the lactacidosis and the decrease in the cerebrovascular resistance is discussed.
The Acetylcholine Content and Cholinesterase Activity of the Bull Retractor Penis Muscle
Authors: Klinge Erik
Published: December 2008

The acetylcholine content of the bull retractor penis muscle, duodenum and urinary bladder was assayed By super fusion of the eserinized frog rectos muscle. The capacity of retractor homogenates to split acetyl‐β‐methylcholine, butyrylcholine and acetylcholine was estimated with the manometric technique. The acetylcholine content of the retractor was of the same order of magnitude as that of the duodenum, but it was twice as high as the amount found in the urinary bladder. A moderate activity of acetylcholinesterase and non‐specific cholin esterase was observed. The role of acetylcholine in the function of the efferent nerve fibres running in the bull retractor is discussed. So far as the classical definitions are applied it is regarded as unlikely that it serves as a neurohumoral transmitter substance either at ganglionic synapses or at neuro effector junctions. There is as yet no conclusive explanation for the mode of action of acetylcholine in these nerve fibres.
Catechol‐O‐Methyl Transferase and Monoamine Oxidase Activity in Some Tissues of the Bull
Authors: Klinge Erik
Published: December 2008

The catechol‐O‐methyl transferase activity in the retractor penis muscle, liver, and kidney of the bull was determined by measuring the amount of metanephrine formed from adrenaline when S‐adenosylmethionine was used as methyl donor. The monoamine oxidase activity in the same tissues was estimated By measuring the rate of disappearance of 5‐hydroxytryptamine added to the incubation mixture. There was a very low, if any, catechol‐O‐methyl transferase activity in the retractor muscle, a slight but distinct activity in the kidney, and a high one in the liver. The monoamine oxidase activity exhibited By the retractor muscle was moderate. In the liver the activity of this enzyme was high but it was still clearly exceeded by that in the kidney. The role of both enzymes in the function of the retractor muscle is briefly discussed.
Transient Dynamics of Ventilation and Heart Rate with Step Changes in Work Load from Different Load Levels
Authors: Broman Svetlana , Wigertz O.
Published: December 2008

Broman, Svetlana and O. Wigertz, Transient dynamics of ventilation and heart rate with step changes in work load from different load levels. Acta physiol. scand. 1971. 81. 54–74.

Transient dynamics of ventilation (V̇) and heart rate (HR) in response to 650 kpm/min step changes in work load were analyzed in six male athletes performing submaximal cycling exercise in the supine position, with the steps initiated at different levels of stable‐state exercise, including “loadless” pedaling (0 kpm/min). By applying mathematical parameter identification, the responses of V̇ to both positive and negative step changes in work load could be accurately described by first‐order exponential models. With the positive steps initiated at 0, 300, and 650 kpm/min, the means of the time constant estimates for V̇ ranged from 67 to 101 sec, and seemed to be independent of the initial work level. Shifting from rest to pedaling at zero load and back to rest caused abrupt changes in V̇, whereas this was rarely the case after step changes from one work load to another with the subjects already pedaling. The responses of HR required second‐order models, with the two time constants ranging from 9.0 to 11.7 sec and from 1.8 to 3.7 min, and with the share of the slower component increasing with the initial work level. Pure time delays were negligible, indicating that the early readjustments in both V and HR are under neurogenic influence. The results support the notion that in exercise the respiratory and circulatory control systems exhibit dissociated dynamic properties.
Intracellular Distribution of Phospholipases in the Rat Pancreas
Authors: Arnesjö Bo
Published: December 2008

The intracellular distribution of free and potential phospholipases (EC 3.1.1.4) has been studied using isopycnic gradient centrifugation 06 rat pancreatic homogenates. 30 % of the free phopsholipase A2 activity was found in the zymogen granules while only 15 % of the total phospholipase A activity was present there. Tryptic digestion increased the phospholipase A activity 20 fold‐an increase only in phospholipase A2 activity. The zymogen granules accounted for 30 % of the prophospholipase and revealed a specific activity (activity per mg protein) 3 to 5 times higher than those of the other cell components. The intracellular distribution of prophospholipase is similar to lipase.
Characterization of Neuronal and Glial Fractions Separated in Sucrose and Ficoll Media
Authors: Hemminki K. , Holmila E.
Published: December 2008

Rat brain cerebral cortices were dispersed by a collagenase‐hyaluronidase treatment and the suspensions obtained were fractionated in sucrose and Ficoll systems by centrifugation. For sucrose a short sedimentation run was followed by a density gradient; for Ficoll only a density gradient was used. Isolated cell populations were examined by light microscopy and differential cell counts were taken. Separation in sucrose yielded more homogenous but smaller fractions. In Ficoll up to 37 million neuronal and glial cells could be collected from 5 cortices. Cells isolated in sucrose and Ficoll contained 70 and some 50 pg protein, respectively.

Neuronal and glial cells separated in sucrose and Ficoll systems accumulated potassium, and were metabolically active. Both respiration and incorporation of radioactive leucine into protein were clearly more active in neuronal fractions. In Krebs‐Ringer phosphate buffer containing 10 mM glucose, neurons respired 946 and 875, and glia 706 and 396 nmoles oxygen/mg protlhr after sucrose and Ficoll separation respectively. Incorporation of radioactive leucine into protein was 5370 and 4980 dpm/mg prot for neurons, and 3110 and 4480 dpm/mg prot for glia. On the other hand, no clear difference was found in TCA‐soluble radioactivities be tween neuronal and glial fractions.
Lipids of the Sympathetic Nerve Trunk Vesicles. Comparison with Adrenomedullary Vesicles
Authors: Lagercrantz Hugo
Published: December 2008

The phospholipid and cholesterol contents of isolated nerve trunk vesicles were analyzed in a preparation obtained from bovine splenic nerves, made up to about 40 % of noradrenaline storage particles. The cholesterol/phosholipid ratio and the relative phospholipid composition of this preparation were about the same as in adrenal medullary vesicle preparations. How ever, lysolecithin, which is a characteristic constituent of the chrornaffin cell vesicles, was found only in trace amounts in the nerve vesicle preparation. The results support earlier findings of biochemical similarities between the water insoluble phase of the two types of amine storage vesicles.
Diameter and Elasticity of the Ascending Aorta during Infusion of Noradrenaline
Authors: Aars H.
Published: December 2008

The effect of smooth muscle contraction on diameter and elasticity of the ascending aorta was examined in 18 anesthetized rabbits. Aortic diameter was measured with ultrasonic technique inside the intact thorax, and blood pressure was recorded from a catheter in the right common carotid artery. Control observations were obtained at various blood pressure levels by producing stepwise changes of the blood volume. At diastolic pressures from 40–90 mm Hg, i.v. infusion of noradrenaline (4–6 μg/kg · min) caused a 6.6% average reduction in diastolic aortic diameter. Noradrenaline at low pressures increased the aortic pressure‐strain elastic modulus (Ep) and theoretical pulse‐wave velocity (PWV) by 30–67%. Control values of Ep and PWV were slightly higher for rabbits than those usually found in dogs. It is concluded that at comparable pressures, contraction of aortic smooth muscle tissue, induced by infusion of noradrenaline, produces a small but significant constriction of the ascending aorta, and, at low pressures only, increases dynamic stiffness of the vessel.
Increased Nerve Stimulation Induced Release of Noradrenaline from the Rabbit Heart after Inhibition of Prostaglandin Synthesis
Authors: Samuelsson Bengt , Wennmalm ÅKe
Published: December 2008

The effect of inhibition of prostaglandin synthesis on the release of noradrenaline induced by sympathetic nerve stimulation was studied in the isolated perfused rabbit heart. It was found that 5,8,11,14‐eicosatetraynoic acid, a compound known to block prostaglandin synthesis in vitro, decreased the outflow of prostaglandins normally induced by nerve stimulation. Simultaneously the outflow of noradrenaline in response to nerve stimulation increased. Since the acetylenic acid did not affect the uptake of exogenous noradrenaline, the increased outflow probably reflects an augmented release of transmitter from the neurons. It has earlier been shown that exogenous prostaglandins inhibit the release of noradrenaline from adrenergic neurons, and that endogenous prostaglandin‐like substances are released in response to sympathetic nerve stimulation in amounts sufficient to exert this inhibitory action. Thus a prosta‐glandin‐mediated negative feed‐back control of the release of adrenergic transmitter is known to be feasible. The present observation that inhibition of prostaglandin synthesis enhances the release of noradrenaline, provides the first conclusive evidence for the occurrence of such an endogenous control mechanism.
The Influence of Physical Training and Other Factors on the Subjective Rating of Perceived Exertion
Authors: Ekblom Björn , Golobarg Alberto N.
Published: December 2008

The relationship between the subjective rating of perceived exertion (RPE) and different physiological variables during work were investigated in 19 healthy subjects under the following conditions: 1) after heart rate (HR) has been experimentally changed during work by the use of autonomic nervous system blocking agents. 2) during different types of physical work and 3) before and after an 8 week period of physical training, respectively. In most work situations, HR mirrors the physical strain subjectively experienced. However, this good correlation between HR and RPE was altered during the experiments with blocking agents. Therefore, a tachycardia as such is not the primary factor in the setting of HR during exercise — RPE was higher for a given level of oxygen uptake during arm work than during leg work, as well as during bicycling compared to running or swimming. A better correlation was found in these experiments between RPE and blood lactate concentration. After training, and in parallel to the decrease in HR at submaximal work loads, RPE was lower for a given level of oxygen uptake, but was the same when related to the “relative” (per cent of maximum) oxygen uptake.
General Characteristics of Sympathetic Activity in Human Muscle Nerves
Authors: Delius W. , Hagbarth K.‐E , Hongell A. , Wallin B. G.
Published: December 2008

Multiunit sympathetic activity was recorded from muscle nerve fascicles in the median or peroneal nerve of resting, relaxed human subjects. The impulses, which were reversibly abolished by a Sympathetic ganglion blocking agent, were grouped in the pulse rhythm, and series of such pulse rhythmic bursts of impulses regularly appeared during spontaneously occurring blood pressure reductions, whereas temporary blood pressure elevations were associated with neural silence. The findings agree with the notion that the sympathetic muscle nerve activity recorded consists of vasoconstrictor impulses, the outflow of which is modulated by a strong phasic and tonic inhibitory baroreflex influence. The reflex delay from an arterial pulse wave to the corresponding inhibition of efferent sympathetic activity was 0.9–1.4 seconds, depending on the recording site. Several stimuli, such as sudden chest compression, a rapid deep breath or an electrical shock against the skin, caused a transient inhibition of the sympathetic discharges lasting a few seconds.
Uptake of Atropine and Methylatropine by Immature Choroid Plexus in vitro*
Authors: Winbladh B.
Published: December 2008

Choroid plexa from newborn rabbits accumulate atropine and methylatropine in vitro by a mechanism which fulfils the requirements for activie transport. Tissue medium ratios at a fixed concentration increase from 3 days before term until 2 weeks of age, when adult levels are reached. Uptake maximal velocity per unit tissue wet weight (Vmax) increases with age, while apparent Km remains constant. The conclusion is drawn that the same carrier mechanism is involved in the newborn and adult tissues. The change in Vmax is discussed in relation to developmental changes in tissue composition and morphology. Further, possible in vivo significance of the in vitro findings is discussed.
Measurement of Blood Flow in Adipose Tissue from the Washout of Xenon‐133 after Atraumatic Labelling
Authors: Nielsen S. Levin
Published: December 2008

The experiments were performed on isolated, autoperfused subcutaneous tissue in urethane‐anesthetized female rabbits. Directly recorded blood from adipose tissue averaged 6.6 ml/100 g‐min (S. D. 4.2, 11 expts.). The blood flow calculated from the washout of Xenon‐133 with an average partition coefficient on 11.8 (ml/g) was 7.4 ml/100 g‐min (S. D. 5.3, 11 expts.). A direct proportionality was found between blood flow in adipose tissue calculated from the washout of Xenon‐133 and directly recorded blood flow. The coefficient of correlation was 0.995 (p < 0.001). When blood flow was constant during the experiments, the washout curves were monoexponential. In the preparation used, the adipose tissue appears to have homogeneous distribution of blood flow and it is likely that diffusion equilibrium of the highly diffusible, inert gases exists between adipose tissue and blood during the washout. The discussion contains a survey of the recently found values of blood flow in adipose tissue obtained with different techniques.
Chloride Transport across Isolated Frog Skin
Authors: Kristensen Poul
Published: December 2008

Kristensen, P. Chloride transport across isolated frog skin. Acta physiol. scand. 1972. 84. 338–346.

A net inward transport of chloride was found to occur in isolated skins of Rana temporia. This transport was not dependent on sodium transport and was inhibited by diamox, thio‐cyanate and bromide. The active chloride transport was not affected by changes in the transepithelial potential difference. On the other hand, the curve describing efflux as a function of potential difference was found to have a shape resembling the shape of the Goldman equation.

Graphical determination of apparent pools showed the influx pool to be about six times greater than the efflux pool. Diamox had no effect on efflux pool size but reduces the apparent influx pool so that it becomes about equal to the efflux pool. This means that at least part of the paths for active and passive chloride movements are different.

A working hypothesis is put forward, according to which chloride is actively transported across the outward facing membrane of the outermost living cell layer of the frog skin epithelium, and the main part of the passive flux occurs across the tight seals and via the interspace system.
Excitability of the Acoustic m. Stapedius and m. Tensor Tympani Reflexes in the Nonanesthetized Rabbit
Authors: Borg Erik
Published: December 2008

Middle ear muscle responses to tone bursts (0.5 to 12.0 kHz) were studied in nonanesthetized, unrestrained rabbits. The combined (total reflex) and the separate activity of the two muscles were recorded as changes of acoustic impedance in both ears simultaneously. The mean threshold of the ipsilateral total reflex, defined as the stimulus intensity eliciting 10 % of maximal response, was 98 dB SPL at 0.5 kHz and fell 12 dB/octave up to 2.0 kHz. Above 4.0 kHz it was about 70 dB SPL. The m. stapedius reflex was not found to differ from the total reflex, whereas the threshold of the m. tensor sympani reflex was about 10 dB higher at all frequencies. The crossed reflexes were significantly less sensitive than the ipsilateral reflexes. The stimulus‐response curves of the m. tensor tympani were less steep than those of the m. stapedius and reached their maxima at a higher sound level. The time course of the responses was interpreted to show nonlinear properties of the reflex system. The sensitivty to acoustic stimulation in the rabbit was found to be significantly higher than in man. The relationship between the activities of the two muscles as well as differences between species are discussed.
Muscle Metabolites with Exhaustive Static Exercise of Different Duration
Authors: Karlsson Jan , Ollander Bo
Published: December 2008

Concentrations of ATP, CP, glycogen and lactate were determined in the lateral portions of the thigh at rest and at different percents (75, 50, 25 and 10 %) of the individual maximal voluntary isometric contraction (MVC). Endurance times were 0.5, 1.6, 5.8 and 38.7 min respectively. A phosphagen depletion of 15 mmol x kg‐1 wet muscle and a lactate accumulation of 20 mmol x kg‐1 was obtained only with the 50 % MVC which is similar to what is observed with short time exhaustive bicycle exercise. At both higher and lower intensities phosphagen depletion and lactate accumulation were less.
On the Descending Control of the Lumbosacral Spinal Cord from the “Mesencephalic Locomotor Region”
Authors: Grillner S. , Shik M. L.
Published: December 2008

Continuous stimulation (60 c/s) of a region below the inferior coliculus can induce locomotion on the treadmill of precollicular, postmammilar cats. This study aims at revealing what changes occur in the spinal cord, when the “locomotor region” is stimulated. This stimulation enables the cat to walk if the treadmill is moved. After controlling the threshold for evoking good locomotion, the cats were curarized. Stimulation at a strength that evoked walking prior to curarization induced a depression of inhibitory short‐latency reflex effects to α‐motoneurones from cutaneous, and high threshold muscular afferents without changing the direct excitability of α‐motoneurones. The threshold for evoking longlasting reciprocally organized discharges was lowered. The results suggest that the effects are induced by a slow fiber system, that releases the activity of the spinal stepping generating neurones. The results would be explained if the noradrenergic reticulospinal system was activated from the mesencephalic locomotor region.
Mucosal Lesions in the Small Intestine of the Cat during Low Flow
Authors: ÅHrén Christer , Haglund Ulf
Published: December 2008

The mucosal changes, produced at the villous tips of the cat small intestine during a mimicked shock situation (regional hypotension at 30 mm Hg during nervous vasoconstrictor fibre activation), were examined macro‐and microscopically. Macroscopically, petechial bleedings and ulcerations were regularly seen in the mucosa after a 2 h hypotensive period. The microscopic findings were characterized by epithelial lifting of various degrees at the tips of the villi and in some cases by a complete denudation of the villous tips. Intraluminal perfusion of a segment with oxygenated saline during the hypotension prevented or greatly reduced the mucosal lesions compared to control segments. On the other hand, intraluminal perfusion with nitrogenated saline did not change the mucosal lesions as compared with control. This strongly indicates that hypoxia per se plays an important role in the pathogenesis of the mucosal lesions, while the intestinal content (e.g. energy substrates or enzymes) does not appear to be of any great importance. It is suggested that the hypoxia is caused by an extravascular shunting of oxygen in the intestinal countercurrent exchanger.
Colonic Motility in the Cat
Authors: Rostad Hans
Published: December 2008

Rostad. H. Colonic motility in the cat. III. Influence of hypothalamic and mesencephalic stimulation. Acta physiol. scand. 1973. 89. 104–115.

Colonic motility recorded with sensitive extraluminal strain gage transducers was studied in lightly anesthetized cats following electrical stimulation of hypothalamic, and mesencephalic structures. Stimulation of various structures of the hypothalamus produced the following: 1) The sympatho‐inhibitory area in the anterior hypothalamus increased colonic activity concomitantly with a fall in blood pressure. 2) The ventral anterior and lateral hypothalamus produced excitatory colonic effects, but these were usually associated with a rise in blood pressure. Similar effects were obtained from the dorsal part of the ventromedial hypothalamic nucleus. 3) Stimulation of the ventral part of the hypothalamus, mainly corresponding to the course of the medial forebrain bundle, and the ventral part of the ventromedial nucleus, resulted in inhibitory colonic effects. Stimulation of various structures of the mesencephalon produced the following: 1) The central gray substance, red nucleus and reticular substance elicited increased colonic effects, most conspicuous in the proximal part of the colon. These responses were usually associated with a blood pressure rise. 2) Points within the central tegmental tract and the medial lemniscus resulted in inhibition of colonic motility. The. functional significance of the results and their relation to behavioural patterns are discussed.
Glycogen Depletion Pattern in Human Muscle Fibres During Distance Running
Authors: Costill D. L. , Gollnick P. D. , Jansson E. D. , Saltin B. , Stein E. M.
Published: December 2008

Costill, D. L., P. D. Gollnick, E. D. Jansson, B. Saltin and E. M. STEIN. Glycogen depletion pattern in human muscle fibres during distance running. Acta physiol. scand. 1973. 89. 374–383.

Muscle biopsy and venous blood samples were taken from 9 subjects before and after a 30 km race. Additional measurements were made when 8 subjects ran 20.5 km of the course 2‐3 weeks later. Information about total metabolism and the glycogen depletion pattern in the fibres of the thigh muscle during prolonged running has been obtained from these measurements. The average oxygen uptake and respiratory exchange ratio were 4.7 1×min‐1 (83 % ot maximal oxygen uptake) and 0.90, respectively. An average intramuscular tryglyceride reduction of 2.2 mmoles×kg‐1 (30 %) accounted for only part of the lipid combusted. Muscle glycogen declined 56 % (from 98 to 42 mmoles of glucose units × kg‐1) during the race. Histochemical staining of the muscle for glycogen revealed a marked depletion in the slow twitch fibres. Only a small glycogen depletion occurred in the fast twitch fibres. This suggests a primary reliance upon slow twitch fibres during prolonged running. The results also point to the limitations of assessing substrate utilization or availability in working fibres from muscle samples with mixed fibre populations.
Rat Liver Glucokinase Activity Studied in Liver Perfusion System
Authors: Hoddevik G. , Spydevold Ø.
Published: December 2008

Attempts were made to demonstrate an adaptive increase in glucokinase in isolated perfused livers. Several physiological factors, such as insulin, hydrocortisone, high glucose and low fatty acid concentrations, which may have a regulatory effect on the adaptive process in vivo were tested. None of these were sufficient to bring about the adaptation in vitro. Glucokinase of livers from fasted rats and then perfused with either bicarbonate buffer, 100 % blood or with mixtures of these media were studied. The concentration of free fatty acids in the media was decreased by addition of insulin and elevated by anti‐insulin serum. These changes were not accompanied by change in glucokinase activity. A moderate decrease in glucokinase in livers from carbohydrate fed rats was observed when the livers were perfused for several hours with subphysiological glucose concentration in the medium. The enzyme was quite stable, however, when glucagon was added to the system. The adaptive increase in glucokinase activity could be demonstrated if the fasted rats were refed a carbohydrate diet for 3 hours before the livers were excised. However, addition of insulin to the perfusion medium was not necessary. When the protein synthesis inhibitor cyclohemixide was added to the perfusion system, the glucokinase from carbohydrate fed liver was quite stable whereas the enzyme in standard diet fed rat livers decreased significantly within 6 hours from the start of the perfusion. This indicates a different turnover rate of the enzyme under different physiological conditions.
Urinary Excretion of Noradrenaline after Treatment with α‐Methyldopa: Inhibition by a Central Nervous Mechanism
Authors: Andén Nils‐Erik , Henning Matts
Published: December 2008

Normal rats treated with L‐α‐methyldopa (400 mg/kg i.p.) after inhibition of the peripheral L‐DOPA decarboxylase by α‐methyldopa hydrazine excreted significantly less noradrenaline in the urine. The adrenaline excretion was only insignificantly reduced. The results indicate that treatment with a‐methyldopa can inhibit the release of noradrenaline from the sympathetic nerves by decreasing the impulse flow from the central nervous system. The adrenal medulla is influenced to a smaller degree.
An Autoradiographic Study of the Intestinal Absorption of 22Na
Authors: Jodal Mats
Published: December 2008

The distribution of 22Na within the villous tissue was studied by means if an autoradiographic technique during absorption of different saline solutions containing the tracer, the resolving power being about 10 μm. After the first minute of absorption most of the grains were localized in the epithelial cells, the grain density in the lamina propria being low. The same distribution of 22Na was seen after 5 min incubatlon during maximal vasodilatation and during absorption of a hypotonic saline solution. On the other hand, a constant intraluminal perfusion of isotonic saline for 30 min changed the autoradiographic picture, the highest radioactivity concentration now being found in the lamina propria. The gradient of grain density along the villous length was, however, not as marked as that reported by Haljamae et al. (1973), who proposed that this gradient was created by a countercurrent multiplication of sodium in the hairpin vascular loops in the villi. The results in this paper support the hypothesis that both sodium and water are crossdiffusing in such a system between the vessels constituting the countercurrent exchanger.
Carbonic Anhydrase in the Cornea
Authors: Lönnerholm Gudmar
Published: December 2008

Carbonic anhydrase activity in the corneas of adult man, human fetus, monkey, rabbit, rat, cow, pig and American bullfrog was examined by the histochemical method of Hansson. In all species the endothelial cells were intensely and distinctly stained for carbonic anhydrase activity. The enzyme inhibitor acetazolamide at 10‐‐5M in the incubation medium completely, and at 10‐‐6M almost completely, inhibited the staining. There was no staining in other parts of the cornea with the possible exception of a few cells in the frog epithelium. Endothelium, epithelium and stroma of cow and rabbit corneas were dissected and homogenized. The carbonic anhydrase activity was determined by a changing pH, indicator method. Only the endothelium showed activity and this was sensitive to inhibition by acetazolamide.
Role of the α‐Receptor in the Control of Noradrenaline Release from Sympathetic Nerves
Authors: Hedqvist Per
Published: December 2008

Phenoxybenzamine, hydergin and phentolamine, all markedly increased the overflow of 3H‐nor‐adrenaline in response to transmural stimulation of the guinea pig vas deferens. After phannacological blockade of neuronal and extraneuronal uptake of noradrenaline, and after inhibition of local prostaglandin formation, the three compounds were still effective and caused increased overflow of 3H‐noradrenaline. This effect was abolished by prostaglandin E2. Using the same pharmacological blockade, noradrenaline and methoxamine inhibited stimulated overflow of “H‐noradrenaline in a dose‐dependent manner. It is concluded that the activity of α‐receptors Per se can feed back regulate the release of noradrenaline from sympathetic nerves. The possibility that the receptors are presynaptically located and that they act on Ca++ influx into the neuron is discussed.
Stimulation of Lymphocyte Release from the Spleen by Theophylline and Isoproterenol
Authors: Ernström U. , Sandberg G.
Published: December 2008

The effect of theophylline and isoproterenol on the splenic release of lymphocytes into the blood was studied in guinea pigs by the comparison between the content of cells in splenic afferent and efferent blood, combined with determination of the blood flow through the spleen.

An intracardial injection of theophylline, like that of isoproterenol, resulted in a greatly increased release of lymphocytes from the spleen as compared to that in control animals. The effect of theophylline, in contrast to that of isoproterenol, could not be abolished by pretreatment with propranolol. The similar effects of theophyliine (known to inhibit the degradation of cAMP) and isoproterenol (known to stimulate the synthesis of cAMP) on the splenic release of lymphocytes to the blood suggest that these effects may be mediated by an increase of intra‐cellular cAMP. This suggestion is supported by our finding of an additive effect when theophylline and isoproterenol were administered in combination.

The abovementioned release of lymphocytes was found shortly after administration of the drugs. After isoproterenol it was followed by an inhibited release of lymphocytes from the spleen. This was in contrast to the much longer duration of the releasing effect of theophylline.
Trapping of Radioactive Microspheres in the Pregnant and Non‐Pregnant Rabbit
Authors: Greasy Robert K. , Kahanpää Kari V. , Swiet Michael de
Published: December 2008

We injected radioactive microspheres, 15, 25 and 50 μn in diameter in the left ventricle or the lower aorta of rabhits and counted the radioactivity in the lungs to estimate the fraction of microspheres shunted through the systemic circulation. The degree of microsphere shunting was inversely proportional to microsphere diameter. The maximum fraction of 15 μm micro‐spheres shunted after an aortic injection was 8.8 % as compared with 6.2 % with 25 μm spheres and 1.2 % with 50 μm spheres. There was no statistically significant change in the fraction of microspheres shunted in pregnancy or with anesthesia. Shunted microspheres may continue to arrive in the lungs for up to 15 min following aortic injection. Microspheres at least 25 μm in diameter should he employed to measure the fractional distribution of cardiac output in rahbits although it may he preferable to use smaller microspheres to measure blood flow within certain organs.
Observations on Closed Tissue Cultures of Sympathetic Ganglia of Chick Embryos in Media Buffered with N‐Tris‐(Hydroxymethyl) Methyl‐Glycine or N‐2‐Hydroxy‐Ethyl‐piperazine‐N‐2‐Ethanesulfonic Acid
Authors: Hervonen Heikki , Rechardt Leena
Published: December 2008

A simple and practical closed tissue culture system for sympathetic ganglia is described. It has proved suitable in metabolic and pharmacological studies of sympathetic neurons, where it is necessary to maintain the neurons in good condition for longer periods. The effects of coverslip, Nerve Growth Factor (NGF) and various concentrations of glucose and serum on nerve fibre growth were estimated in N‐tris(hydroxymethyl)methyl‐glycine (TRICINE) or N‐2‐hydroxy‐ethylpiperazine‐N‐2‐ethanesulfonic acid (HEPES) buffered culture mediums. TRICINE and HEPES buffers were found non‐toxic to the nervous tissue and by these buffers it was possible to avoid CO2‐gassing and to use a closed environment, which facilitated daily checking of explants.

Although the sympathicoblasts were not dissociated before culturing, a monolayer of the neurons with dense network of nerve fibres formed in this culture system. This pattern of growth made it possible to perform histochemical reactions (fluorescence microscopy and electron microscopical histochemical reactions) directly in the culture dishes.
Time Course for Refilling of Glycogen Stores in Human Muscle Fibres Following Exercise‐Induced Glycogen Depletion
Authors: Piehl Karin
Published: December 2008

Muscle biopsy samples were obtained from the thigh muscle of 4 subjects before and after 2 h of work and at selected intervals during the following 46 h when a carbohydrate enriched diet was consumed. Mean glycogen content declined 103 (from 125 to 22) mmol glucose units × kg‐l following exercise. 5 and 10 h after consuming the carbohydrate enriched diet muscle glycogen increased to 64 and 86 mmol glucose units × kg‐l, respectively. During the first 5 h there was a marked storage of glycogen in the muscle which was related to the carbohydrate intake, but pre‐exercise concentrations of muscle glycogen were observed first after 46 h. The increase in glycogen occurred in both fibre types, but the fast twitch fibres replinished their glycogen somewhat faster than did the slow twitch fibres suggesting a higher glycogen synthetase activity. At glycogen concentrations above 80–90 mmol no differences in the glycogen content of the two fibre types could be discerned with histochemical methods.
Denervation Changes in Frog Skeletal Muscle
Authors: Nasledov G. A. , Thesleff S.
Published: December 2008

The effects of denervation on acetylcholine sensitivity and on the electrical properties of frog tonic and phasic muscle fibres were examined by the use of iontophoretic micro‐application of acetylcholine and conventional intracellular techniques for recording and stimulation. In tonic fibres extrajunctional cholinergic sensitivity appeared 4 days after sectioning of the nerve and by 2 weeks the entire membrane had attained a high level of acetylcholine sensitivity. The sensitivity of former end‐plate regions also increased with time. In phasic fibres cholinergic sensitivity appeared about one week later but otherwise followed the same pattern as in tonic fibres. Innervated tonic fibres are incapable of generating action potentials but this property is induced upon denervation. After one week of denervation small spikes were observed in response to depolarizing current pulses and by 2 weeks large action potentials, sometimes followed by repetitive discharges were recorded. Denervation failed to affect the action potential in phasic fibres. Tetrodotoxin completely blocked action potentials in tonic and in phasic fibres. Denervation reduced the effective resistance and the time constant of tonic fibres but had no effect on these properties in phasic fibres. Actinornycin D injected i.p. in a single dose (7.5 or 9.0 μg) failed to prevent the appearance of extrajunctional cholinergic receptors but almost completely blocked the induction of action potentials in denervated tonic fibres.
The Effects of Repetitive Stimulation on the Action Potential and the Twitch of Rat Muscle
Authors: Hanson Jerker
Published: December 2008

Membrane potentials and contraction curves of different types of rat muscle fibre have been studied at body and room temperatures with special regard to the effects of repetitive stimulation. Fast fibres (from the surface of the extensor muscles of the antebrachium) have a higher resting membrane potential, a higher amplitude and shorter duration of the spike of the action potential and a larger early negative after‐potential than soleus fibres. In the fast fibres stimulation at 10 Hz for 30 s produced a decicase of the resting membrane potential, a decrease in the amplitude of the spike of the action potential and an increase in its duration, as well as an increase in the early negative after‐potential. In soleus fibres such changes were rare. These findings indicate that there are differences in the membrane properties between the two types of muscle fibres in addition to previously known differences in mechanical properties. Repetitive stimulation of fast fibres at body temperature caused a rapid increase in the twitch amplitude (staircase phenomenon). This increase occurred before any appreciable change in the action potential. Stimulation at room temperature caused only small changes in the twitch amplitude but marked increase in the twitch duration. This suggests that repetitive stimulation may alter both the amplitude and the duration of the active state curve.
Influence of Aldosterone on Active Sodium Transport by the Toad Bladder: a Kinetic Approach
Authors: Crabbé Jean
Published: December 2008

Sodium transport by the urinary bladder of the toad, Bufo marinus, was analysed by measuring the rate of transfer of radiosodium from the tissue towards the serosal compartment at steady state with respect to labelling from the rnucosal surface. Two sodium pools were identified of which only the fast‐disposal pool (with a half‐time of 1.7 min) reflected the sodium‐transporting activity of the preparation. When transepithelial sodium transport was stimulated by aldosterone, the half‐time of the fast‐disposal sodium pool was not modified. This is taken as additional evidence for the assumption that aldosterone does not influence the handling of sodium by the “pump”.
Sympathetic Vasodilatation, Kallikrein Release and Adrenergic Receptors in the Cat Submandibular Salivary Gland
Authors: Gautvik K. , Kriz M. , Lund‐Larsen K. , Waaler B. A.
Published: December 2008

The adrenergic receptors involved in secretion of kallikrein and the vasodilatation occurring subsequent to sympathetic nerve stimulation have been studied in the cat submandibular salivary gland. Measurements were made of kallikrein content in glandular homogenate and of venous outflow and glandular perfusion pressure. Isoprenaline failed to cause secretion of kallikrein in contrast to sympathetic nerve stimulation and close arterial injections of noradrenaline. Nerve stimulation and noradrenaline reduced the amount of kallikrein in the glands by 60 and 50 per cent, respectively. The α‐blocking agent Regitin® inhibited completely the secretion of kallikrein induced by nerve stimulation, while adrenergic β‐blockade had no inhibitory effect on enzyme secretion. In this gland, therefore, the secretion of kallikrein is mediated entirely through activation of adrenergic α‐receptors.

The β‐blocking agent propranolol reduced the nerve induced vasodilatation by about 40 per cent. This sympathetic vasodilator response was present, but markedly reduced, after pretreatment with Regitin,® which abolished kallikrein secretion and the vasoconstrictor phase of the nerve‐induced vascular response. This study and an earlier report (Gautvik, Kriz and Lund‐Larsen 1972 a) suggest that β‐adrenergic receptors in the glandular vessels, as well as ®aL‐adrenergic receptors involved in the secretion of kallikrein, play a role in the vasodilatation observed in this gland subsequent to sympathetic nerve stimulation.
Glycogen Depletion Pattern in Muscle Fibres of Trotting Horses
Authors: Lindholm Arne , Bjerneld Håkan , Saltin Bengt
Published: December 2008

Five trained standardbred horses were studied trotting at two speeds (300 and 500 m × min‐1) for 4 h and 1 h, respectively, and one horse at maximal speed. Their mean muscle glycogen content was reduced from 103 to 43 mmol × kg‐1 in the 1‐h experiment and from 119 to 48 mmol × kg‐1 in the 4‐h experiment. At maximal trotting speed, muscle glycogen declined from 88 to 46 mmol × kg‐1 in 3 aggregate min of exercise. Glycogen depletion patterns in slow twitch (ST), fast twitch, high oxidative (FTH) and fast twitch (FT) fibres were estimated on the basis of the periodic acid‐Schiff reaction. The ST and FTH fibres were depleted at all exercise intensities. These fibres then probably sustained almost all the exercise at slow trotting speeds as long as their glycogen stores were not depleted. After prolonged trotting and at high speeds, there appeared to be a progressive increase in FT fibre recruitment. Liver glycogen was reduced from 151 to 95 mmol × kg‐1 in the 1‐h run and from 116 to 19 mmol × kg‐1 in the 4‐h run, respectively. The fatigue found in horses trotting for long periods of time or at high speeds could be related to a selective depletion of glycogen in the ST and FTH fibres.
Des Mécanismes Biochimiques de 1'Automatisme Cardiaque. Examen de la Myxine
Authors: Rybak B. , Simon M.
Published: December 2008

Kinetic titrations of cAMP in the branchial heart of Myxitae glutitrosa seem to show that CAMP is involved in automatic processes and that there are quantitative differences in cAMP and specific phosphodiesterase inside the auricle and inside the ventricle in such a way that, compiling the present results with other data, one explains how the auricle is the dominant pacemaker in this heart.
Lowered Sensitivity to Acetylcholine in Hearts from Cold‐Acclimated Rats and Frogs
Authors: Harri M. N. E. , Tirri R.
Published: December 2008

The sensitivity of the heart to the negative chronotropic effect of acetylcholine (ACh) was measuredin vivofrom denervated hearts of the rat and frog before and after they were acclimated to cold. In the frog the possible seasonal changes in sensitivity were also observed. In the rat, cold acclimation lowered the sensitivity to ACh. This change was significant already at 3 days after cold exposure. Cold acclimation lowered the sensitivity to ACh also in the frog, but only during the winter. On the other hand, summer frogs were much niore sensitive to ACh than winter frogs. It was concluded that it is the increased parasympathetic activity in the cold‐acclimated rat and in the winter frog which results in the lowering of sensitivity to ACh.
On the Mechanism of the Enhancement by Smooth Muscle Stimulants of the Motor Responses of the Guinea‐pig Vas Deferens to Nerve Stimulation
Authors: Sjöstrand Nils O. , Swedin Göran
Published: December 2008

Low concentration of various agonists: acetylcholine, adrcnaline, noradrenaline, histamine, serotonin, barium chloride, bradykinin, eledoisin, substance P and angiotensin enhance the motor responses of the nerve stimulated guinea‐pig vas deferens considerably. A similar effect can also be obtained by prostaglandins E1 and E2 although these drugs generally depress the responses of the nerve stimulated vas deferens. By a comparison with the actions of the agonists on the contractions of nerve stimulated vasa deferentia and on contractions of electrically stimulated denervated or tetrodotoxin paralyzed vasa deferentia it is concluded that with the exception of angiotensin and the prostaglandins, the agonists have their main action post‐junctionally on the smooth muscle cells. Angiotensin has mainly a prejunctional action but acts also in part postjunctionally. The prostaglandins have a depressant prejunctional action but a stimulant postjunctional action.