bluuebunny/crossref_metadata_2025 huggingface dataset:
Adenosine Triphosphate Dependent Calcium Uptake by Subcellular Fractions from Bovine Neurohypophyses
Authors: Russell J. T. , Thorn N. A.
Published: December 2008

Bovine neurohypophyses were fractionated by differential and density gradient ultracentrifugation and the Ca2+uptake and ATPase activities in the microsomal, mitochondrial and secretory granule fractions were studied. The microsomal and mitochondrial fractions accumulated Ca2+in the presence of ATP. The accumulation by the latter per mg protein was at least twice as large as by the former. This Ca2+accumulation was accompanied by liberation of inorganic phosphate (Pi). In the presence of sodium azide (2 mM) Ca2+uptake and Piliberation were inhibited in the mitochondrial, but not in the microsomal fraction. Further studies of the microsomal fraction revealed that the ATP‐dependent Ca2+uptake and Piliberation activities were temperature and pH‐dependent and required Mg2+. Both activities were stimulated by very low concentrations of Ca2+(1–10 μM) and were inhibited by EGTA (2 mM). N‐ethyl‐maleimide (2 mM) inhibited both the Ca2+uptake and ATPase activities of the microsomal fraction. These results suggest the presence of a membrane ATPase that is stimulated by both Ca2+and Mg2+. It is suggested that the observed Ca2+uptake activities are involved in maintaining a low axoplasmic free Ca2+concentration, thus playing an important role in the release mechanism of vasopressin by the neuro‐secretory terminals.
No Role for Zinc in the Storage of Histamine in Rat Peritoneal Mast Cells
Authors: Uvnäs Börje , ÅBorg Carl‐Hugo , Bergqvist Ulla
Published: December 2008

The histamine in the granules of mast cells has been proposed to be stored as a heparin‐zinc‐histamine complex. Due to its chelating action zinc should increase (double) the histamine binding capacity of heparin. We have determined the zinc content of isolated rat peritoneal mast cells to 2.4–4.1 nmol/106cells and of their granules to 13.0–21.4 nmol/mg dry weight. The corresponding amounts of histamine were 150 and 680 nmol respectively. The zinc content found is far (20 times) too low to allow for an adequate binding of histamine in a heparin‐zinc‐histamine complex.In vitrothe granules take up zinc in the same manner as they take up other cations and zinc competes with histamine for granule storage sites. Consequently, Hi‐uptake is reduced and not enhanced in the presence of zinc in the suspension medium.In summaryno evidence was found for a storage function of zinc in a heparin‐zinc‐histamine complex.
Distribution of an Adenohypophysial Constituent in the Body I. Whole‐body Autoradiographical Studies in the Mouse
Authors: Kihlström Jan Erik , Hall Håkan , Lakomaa Eeva
Published: December 2008

A peptide with a molecular weight of about 5 000 has previously been shown to affect the output of semen in frogs and probably also in mammals. This sperm‐releasing substance is not part of any known gonadotropic hormone. The distribution of this substance has been investigated using whole‐body auto‐radiography. Radioactive material is incorporated into the epididymis, the adenohypophysis and probably also into the ovary.
The Diffusion Permeability to Water of the Rat Blood‐Brain Barrier
Authors: Bolwig Tom G. , Lassen Niels A.
Published: December 2008

The diffusion permeability to water of the rat blood‐brain‐barrier (BBB) was studied. Preliminary data obtained with the Oldendorf tissue uptake method (Oldendorf 1970) in seizure experiments suggested that the transfer from blood to brain of labelled water is diffusion‐limited. More definite evidence of such a limitation was obtained using the single injection technique of Crone (1963). 14C‐labelled sucrose was used as intravascular reference substance and tritium‐labelled water as test substance. The non‐exchanging (transmitted) fraction, I‐E = T, of labelled water during a single passage increased from 0.26 to 0.67 when the arterial carbon dioxide tension was changed from 15 to 85 mm Hg, a change increasing the cerebral blood flow about sixfold. This finding suggests that water does not pass the blood‐brain barrier as freely as lipophilic gases.
The Relationship between Arterial PO2 and Cerebral Blood Flow in Hypoxic Hypoxia
Authors: Borgström Lars , Jóhannsson Halldor , Siesjö Bo K.
Published: December 2008

The relationship between arterial oxygen tension (PaO2) and cerebral blood flow (CBF) in hypoxic hypoxia was studied in artificially ventilated and normocapnic rats. Changes in CBF were evaluated from arterio‐venous differences in oxygen content after 2, 5, 15 and 30 min exposure to PaO2 85, 75, 55, 45, 35 and 25 mm Hg. In separate experiments the PaO2 was decreased to 25 mm Hg for 1, 2, 5, 15 and 30 min in animals in which PaCO2 was allowed to fall by 5–10 mm Hg. There was a small, gradual increase in CBF when Pao, was lowered in steps from 130 to 55 mm Hg, and a more pronounced increase at PO2 values below 50 mm Hg. At PaO2 25 mm Hg CBF increased to values of 500% of normal. Significant increases in CBF were recorded at PaO2 values of 85 and 75 mm Hg in spite of the fact that previous studies have failed to record an elevatad tissue lactate content at these PO2 levels, and in spite of an unchanged cerebral venous PO2. When the PaO2 was reduced to 25 mm Hg CBF increased markedly already at 1 and 2 min, and this increase in CBF occurred even if PaCO2 was allowed to fall by 5–10 mm Hg. Previous results have shown that in such short periods enough lactic acid is not formed to induce a net tissue acidosis. The results thus give no support to the hypothesis that cerebral hyperemia in hypoxia is coupled to accumulation of lactic acid in the tissue.
Duration of Central Action of Angiotensin II Estimated by its Interaction with CSF Na+
Authors: Anderson B. , Leksell L. G. , Rundgren M.
Published: December 2008

In pre‐hydrated goats, an urge to drink persisted for approximately half an hour after combined infusions of angiotensin II and hypertonic (0.5 M) NaCl into the lateral or third cerebral ventricle. The intraventricular infusion of angiotensin/glucose solution, having no dipsogenic action of its own, markedly accentuated the dipsogenic and antidiuretic effects of the subsequent intraventricular infusion of hypertonic NaCl. The possibility is discussed that angiotensin may be bound at periventricular receptor sites where it continues to interact with Na+in eliciting thirst and ADH release for about half an hour.
Influence of Autonomic Nerves and Drugs on Myoepithelial Cells in Parotid Glands of Cat
Authors: Thulin Anders
Published: December 2008

When a single electrical shock is applied to either the parasympathetic or to the sympathetic nerves a pressure rise is seen in the parotid duct of the cat, probably due to myoepithelial cell activation. No secretion occurred on single impulse stimulation. When repetitive stimulation was used both divisions of the autonomic nervous system could evoke secretion. The motor response to sympathetic stimulation was mediated via a‐receptors while secretion mainly was mediated via β‐receptors.
The Effect of Stimulation of the Cervical Sympathetic Chain on Regional Cerebral Blood Flow in Monkeys: A Study with Radioactively Labelled Microspheres
Authors: Alm Albert
Published: December 2008

15 μm labelled microspheres were used to determine the effect of stimulation of the cervical sympathetic chain on blood flow through different parts of the brain and through some extracerebral tissues of the head in monkeys. Unilateral stimulation at 10 Hz for one min caused mean reductions in blood flow through the masseter muscle, the parotid gland, and the tongue of 76–94 percent in 9 monkeys, while in the same animals there were no convincing effects on regional cerebral blood flow.
Blood‐Brain Transfer of D‐Glucose, L‐Leucine, and L‐Tryptophan in the Rat
Authors: Brender Jytte , Andersen P. E. , Rafaelsen O. J.
Published: December 2008

Recently Oldendorf developed a method for measurement of the early uptake of substances from the capillary bed into brain tissue after a single capillary passage of a bolus injected rapidly into the common carotid artery of the rat. The uptake of a test substance is expressed relative to the uptake of a highly diffusible reference substance, tritiated water. In this study experimental data are presented allowing to correct the uptake values for the unknown loss of tritiated water, so that the fractional unidirectional uptake (Extraction, E) can be calculated. This method is used to investigate the uptake kinetics for D‐glucose, L‐leucine, and L‐tryptophan. For the three substances investigated the uptake kinetics involved both saturation and linear kinetics. Km values of 11 mM for D‐glucose, 0.16 mM for L‐leucine, and 0.19 mM for L‐tryptophan were found. The uptake capacity, Vm, was calculated using a blood flow value of 0.85 ml/(g × min); Vm was for D‐glucose 1.6, for L‐leucine 0.027. and for L‐tryptophan 0.024 μmol/(g × min). The D‐glucose Vm in the present study is comparable with Vm values in the literature, and indicates that the method may be employed for quantitative analyses of the blood‐brain transfer of solutes.
Brain Energy Metabolism in Anesthetized Rats in Acute Anemia
Authors: Jóhannsson Halldór , Siesjö Bo. K.
Published: December 2008

In order to evaluate if pronounced anemic hypoxia gives rise to signs of cerebral oxygen lack the blood hemoglobin content was reduced to 6 and 3 g.(100 ml)‐1. Cerebral blood flow increased in spite of the fact that there was a moderate reduction in blood pressure, and in mean tissue CO2 tension, and in the absence of signs of an increased glycolytic rate in the tissue. With a reduction in a hemglobin content to 3 g.(100 ml)‐1 there was a moderate increase in tissue lactate content and associated changes in other carbohydrate metabolites and in amino acids of the type seen in hypoxic hypoxia, suggesting that tissue hypoxia was present. However, since the concentrations of phosphocreatine and adenine nucleotides remained constant this hypoxia must have been slight. It is concluded that there is cerebral vasodilation in the brain in pronounced anemic hypoxia, and that this vasodilatation, in combination with the reduced viscosity, creates favourable conditions for cerebral oxygenation.
Compensatory Increase in Choline Acetyltransferase Activity in Salivary Glands and Diaphragm Muscle of the Rat
Authors: EKSTRÖM JORGEN
Published: December 2008

When the function of salivary glands was abolished by applying ligatures to their ducts and the function of one half of the diaphragm muscle was abolished by sectioning of its phrenic nerve, the choline acetyltransferase activity was found to be increased in not duct‐ligated glands and in the intact hemidiaphragm 4 weeks later. The increase was not seen within the first week. The increase in activity appears to be particularly manifested in the nerve endings, since it was seen in the hemidiaphragm but not in the phrenic nerve. Increased stream of impulses in the efferent nerves is thought to be the cause of this increase in choline acetyltransferase activity.
Effects of Drugs and Nerve Stimulation on the Spleen and Arteries of Two Species of Dogfish, Scyliorhinus canicula and Squalus acanthias
Authors: Nilsson Stefan , Holmgren Susanne , Grove David J.
Published: December 2008

The effects of drugs and nerve stimulation on the spleen of 2 species of dogfish have been examined by experiments with perfused spleens and isolated spleen and artery strips. Adrenaline, noradrenaline and phenylephrine, acting via alpha adrenoceptors, constrict the perfused spleen of both species, thereby releasing erythrocytes, and contract the isolated spleen and artery strips. Phentolamine competitively antagonizes the excitatory effects of adrenergic agonists. The responses of the spleen to acetylcholine are very irregular, and a rapid desensitization makes evaluation of the mode of action of this drug difficult. In the artery strips acetylcholine produces a dose‐dependent contraction. Fluorescent histochemistry reveals well developed adrenergic innervation of the arteries, and a few adrenergic terminals in the spleen. Stimulation of splenic nerves produces normally splenoconstriction in Squalus, which can be blocked by phentolamine but not by atropine. The nervous control of the Scyliorhinus spleen seems to be poor or lacking. It is concluded that the dogfish spleen, and maybe also the arteries, are to a large extent controlled by circulating catecholamines and (in Squalus) also by sympathetic adrenergic fibres.
The Postnatal Development of Some Twitch and Fatigue Properties of Single Motor Units in the Ankle Muscles of the Kitten
Authors: Hammarberg C. , Kellerth J‐O.
Published: December 2008

Contractions of single motor units in the gastrocnemius, soleus and pretibial flexor muscles were elicited by intracellular stimulation of the innervating motoneurones. Kittens being 1, 2, 6 and 10 weeks of age were used. The aim was to establish the pattern of postnatal differentiation of the adult motor unit types (Burke et al. 1973, 1974, Hammarberg and Kellerth 1975 b). In the developing type S units of the soleus muscle the mean value for contraction time showed a transient decrease during the early postnatal period, but the twitch half‐relaxation time (HRT), the duration of motoneurone post‐spike afterhyperpolarization (AHP) and the susceptibility to fatigue remained virtually unchanged during the age period studied. In the units of the developing fast twitch muscles the contraction time, HRT and susceptibility to fatigue were significantly different from those of the soleus units already at 1 week of age. At 6–10 weeks of age the contractile characteristics typical of the adult type FF and FR units were attained. The AHP duration gradually decreased up to 10 weeks of age, and it was then considerably shorter than both at 1 week of age and in the adult stage.
Relative Contribution of Superficially Bound and Extracellular Calcium to Activation of Contraction in Isolated Rat Portal Vein
Authors: Sigurdsson Stefan B. , Uvelius Bengt , Johansson Börje
Published: December 2008

The spontaneous electrical and mechanical activity of the isolated rat portal vein is abolished after only 2–3 min in nominally Ca‐free medium, and after 5–6 min there is no contractile response to depolarizing (122 mM K+), Ca‐free solution. In the present study we have examined the electrical and mechanical responses of the portal vein to depolarization with simultaneous readministration of Ca2+ (2.5 mM) after periods of variable length in Ca‐free standard solution. After 30 to 60 min of Ca depletion a slow contracture occurred in response to the high‐K+ solution with 2.5 mM Ca2+. When the period in Ca‐free medium was reduced below 30 min an early, faster phase appeared in the contracture response, and this phase was more rapid the shorter the time of Ca depletion. It is suggested that the slow contracture obtained after 30 min or more uses mainly extracellular Ca for activation and that the faster phase seen after shorter periods of Ca depletion is due to release of superficially bound Ca. This latter pool of tissue bound Ca does not alone produce contraction in response to depolarization, suggesting that extracellular Ca is required to trigger the release perhaps through a regenerative process.
Inhibition of Induced Pinocytosis in Amoeba proteus by Membrane Stabilizing Drugs
Authors: Josefsson J.‐O. , Johansson G. , Hansson S. Elisabeth
Published: December 2008

The effect of membrane stabilizing drugs on cation induced pinocytosis was studied inAmoeba proteus.Initially the presence of local anesthetic drugs during a pinocytosis cycle had a stimulating effect on channel formation, however, the capacity to develop pinocytotic channels was reversibly inhibited after a period of treatment with these drugs. Imipramine, vinblastine and the phenothiazines had effects similar to local anaesthetics. The local anesthetics inhibited pinocytosis in the following order: dibucaine>tetracaine> bupivacaine >lidocaine>procaine, and the phenothiazines: thioridazine>prochlorperazine>chlorpromazine > prometazine. Pinocytosis, when induced by Na+or tris, was more affected by the drugs and by calcium binding agents than pinocytosis induced by K+. After pretreatment with inhibitory concentration of dibucaine (3 × 10‐4M) the depolarization of the membrane and the conductance increase during pinocytosis were normal, while the increase of oxygen uptake during the pincoytosis cycle was abolished. Addition of Ca++before, during or after dibucaine treatment decreased the effect of the drug. Conversely, in dibucaine‐treated cells, cation induced pinocytosis was less inhibited by Ca++than pinocytosis in normal cells. Addition of EGTA to the inducing solutions potentiated the inhibitory effect of the drug. It is suggested that these drugs release Ca++from the cell surface and at higher concentration or after prolonged incubation time interfere with a Ca++mechanism which couples the membrane and contractile systems in the cytoplasm.
Depression of Taste Responses by Local or Intravascular Administration of Salicylates in the Rat
Authors: Hellekant G. , Gopal V.
Published: December 2008

The effects of aspirin and sodium salicylate on the taste response in the chorda tympani proper nerve have been studied during stimulation of the taste receptors in rats with salty, sweet, sour and bitter‐tasting solutions. Three methods of administering the drugs were used: locally on the tongue, intravenously into one femoral vein and intraarterially close to the branching of the lingual artery. It was observed that salicylates, given in any of these three ways, depressed the response to taste stimuli. This is discussed in relation to present views on the action of salicylates.
Kinetics of the Glomerular Ultrafiltration in the Rat Kidney. An Experimental Study
Authors: Källskog Ö. , Lindbom L. O. , Ulfendahl H. R. , Wolgast M.
Published: December 2008

The quantitative relation between the driving forces over the glomerular membrane and the glomerular plasma flow, on the one hand, and the single glomerular filtration rate (SNGFR), on the other, is still uncertain. Micropuncture measurements on Sprague‐Dawley rats made it possible to calculate the net driving force over the glomerular membrane. The single glomerular plasma flow was determined from SNGFR and the single nephron filtration fraction (SNFF). The effective plasma flow was measured with PAH for total kidney and for superficial nephrons. The mean glomerular capillary pressure was found to be 62.6 mm Hg. The results indicate a net driving force of about 13 mm Hg at the distal end of the glomerular capillary. SNGFR was found to be 14.1 nl/min.100 g. SNFF amounted to about 0.27. The filtration fractions determined with the PAH method were in the same range. The results indicate a filtration disequilibrium, in contrast to those of Brenner et al. from measurements on a mutant Wistar rat strain. The filtration fractions seemed to be the same in all glomerular populations. It is clear that the SNGFR is pressure dependent. Our earlier findings of a nonautoregulation of the blood flow through the outer glomeruli were also confirmed.
Effects of Histamine, Vasopressin, and Angiotensin II on Hepatosplanchnic Hemodynamics, Liver Function, and Hepatic Metabolism in Cats
Authors: Krarup N.
Published: December 2008

Continuous i. v. infusions of histamine (5μg/kg·min), vasopressin (10 μ/kg·min), or angiotensin 11 (0.5,μg/kg·min) were given to fasting cats. Hepatic arterial flow was decreased 30% by histamine, increased 30% by vasopressin, and not significantly affected by angiotensin, whereas portal venous flow was increased 25% by histamine, decreased 40% by vasopressin, and not significantly affected by angiotensin. The hepatic arterial conductance was decreased about 25 % by histamine and angiotensin, and not significantly affected by vasopressin. The gastrointestinal conductance was decreased about 40 % by vasopressin and angiotensin, and increased 25 % by histamine. The conductance in the intrahepatic low pressure vessels was not affected by histamine and vasopressin, but decreased 25% during the infusion of angiotensin. These hemodynamic effects, however, were not accompanied by changes in the liver function or hepatic metabolism as judged from the splanchnic elimination of ethanol, the hepatic uptake and excretion of ICG, the hepatic oxygen consumption, and lactate and ketone production. This indicates that the functional capacity of the liver and thereby the number of sinusoids perfused is not markedly influenced by these drugs. Vasopressin caused a decrease in the oxygen consumption and an increase in the lactate production in the prehepatic splanchnic area, which may be due to a redistribution of the gastrointestinal blood flow.
Effect of Vasoactive Agents on the Distribution of Renal Cortical Blood Flow in Dogs
Authors: Tyssebotn I. , Kirkebø A.
Published: December 2008

The distribution of renal cortical blood flow was studied in 6 Nembutal anesthetized dogs during control periods and during infusions of adrenaline, noradrenaline, angiotensin and vasopressin. Local cortical blood flow was measured as H2 gas desaturation rate recorded polarographically by platinum electrodes in outer and inner cortex. The total renal blood flow (RBF) was measured by an electromagnetic flow meter. In the control period the outer cortical blood flow (OCF) and inner cortical blood flow (ICF) averaged 3.59 (±S.D. 0.85) ml/min·g and 3.23 (±S.D. 0.64) ml/min·g, respectively. Infusions of the various vasoactive agents caused essentially equal vascular responses. All agents caused increased local renal resistance and reduction of RBF whether given intravenously or intraarterially. The RBF could be lowered to 20–50 % of initial control flow by increasing doses of vasoactive agents. OCF and ICF fell proportionately and almost to the same extent as RBF, or OCF fell slightly more than ICF. There was no evidence for patchy or zonal hypoperfusion in cortex caused by infusion of adrenaline, noradrenaline, angiotensin and vasopressin.
Time Courses of Pulmonary Gas Exchange and Heart Rate Changes in Supine Exercise
Authors: Karlsson Hans , Lindborg Bertil , Linnarsson Dag
Published: December 2008

The time courses of ventilation (VE), 02 uptake (V̇O2), CO2 elimination (V̇co2), respiratory exchange ratio (R), end‐tidal Po2 and Pco2 and heart rate (HR) were studied in seven subjects performing light dynamic leg exercise in the supine position. Individual and group mean time courses in response to step changes in work load were computed and displayed graphically. A computer‐based method was also used to fit mono or bi‐exponential mathematical functions to the recorded responses. The over‐all rate of HR change in response to the transition from 0‐load pedalling to exercise (on‐response) was faster (mean response time, MRT = 31 s) than the corresponding V̇o2 response (MRT = 45 s) while V̇E responded considerably slower (MRT = 86 s). During the reverse transition (off‐response), V̇o2 and V̇E changed with the same rate as in the on‐response, while the HR‐change was slower than during the on‐response (MRT = 50 s). During the initial 15‐sec period, V̇O2, changed only slightly, which contrasts to previous results in the sitting position, where 50% of the final change in V̇o2, has been reported to occur within the first 15‐sec period, and where changes in blood distribution and stroke volume are known to be more pronounced than in the supine position. Our results emphasize the importance of central circulatory changes for the time course of V̇o2, at the start and end of exercise.
On the Possible Involvement of Sulphomucopolysaccharides in the Storage of Catecholamines within the Central Nervous System
Authors: Pycock Chris , Blaschke Eleonora , Bergqvist Ulla , Uvnäs Börje
Published: December 2008

Rats treated at birth with 6–OH DA were sacrificed in adult age 24 h after an injection of3H‐NA. Synap‐tosomes were isolated from the cerebral cortex, the hypothalamus, the pons‐medulla region and the cerebellum. The similar distribution pattern of3H‐NA and36S on gradient centrifugation of the synapto‐some preparations, the similar effect of 6–OH DA on the uptake of3H‐NA into slices of brain tissuein citroand on their35S content as well as the identification of chondroitin and heparan sulphate in the synapto‐some fractions are observations which indicate a possible function of SMPSs in the storage of NA in adrenergic terminals.
The Interstitial Space of Adipose Tissue as Determined by Single Injection and Equilibration Techniques
Authors: Linde Birgitta , Chisolm Guy
Published: December 2008

The interstitial 14C‐sucrose space was determined in the subcutaneous adipose tissue of the dog using both a single injection‐indicator dilution technique and an equilibration‐tissue sampling method. 131I‐albumin and 51Cr‐labelled erythrocytes served as intravascular indicators. The conventional extrapolation method for single injection curves yielded space values several times lower than those measured by the equilibration technique, although sampling was continued until the venous outflow samples contained less than 1 % of the peak 14C‐sucrose activity. This discrepancy may be due to long transit times, for which the conventional extrapolation procedure does not account. An extrapolation procedure is proposed based on the assumption that the area under the normalized extra‐ and intravascular curves should be equal. By this procedure as well as by the equilibration technique the interstitial 14C‐sucrose space in adipose tissue measures approximately 10 ml × 100 g‐1. The single injection technique does not appear applicable for space determinations in adipose tissue during sympathetic nerve stimulation (3–7 Hz), possibly due to “trapping” of the tracers within the tissue.
Secretion of Anterior Pituitary Hormones in Man: Effects of Ethyl Alcohol
Authors: Leppäluoto J. , Rapeli M. , Varis R. , Ranta T.
Published: December 2008

The possibility that previously described effects of ethyl alcohol on peripheral endocrine glands might be mediated via pituitary prompted this investigation on the effects of ethanol on anterior pituitary secretion. Nine healthy male subjects were given beverage containing ethanol (1.5g/kg) or beverage alone per os in a randomized cross‐over study and plasma ACTH, FSH, GH, LH and TSH were measured by specific radio‐immunoassays up to 15 h and the urinary levels of adrenaline and noradrenaline by fluorometry. A combined LRF and TRF test was also carried out in similar series of experiments. During the whole experiment there were no significant differences in the plasma levels of ACTH, FSH and TSH or in the urinary levels of adrenaline and noradrenaline between ethanol treated and control subjects. Plasma FSH, LH and TSH responses to LRF and TRF stimulation were also similar in alcohol treated and control subjects. Plasma ACTH values were high (113–270 pg/ml) both in control and ethanol experiment suggesting that the subjects experienced apprehension toward the experiment. Plasma GH level exhibited a non‐sleep related burst in the late evening (from 0.4 ng/ml at 6 p.m. to 3.1 ng/ml at 10 pm., p < 0.01). This increase was not seen after alcohol ingestion (p < 0.01). Plasma LH levels were significantly lower after 6 and 13 h in alcohol treated subjects than in controls (65 us, 106 ng/5ml, p < 0.01 and 74 us, 121 ng/ml, p < 0.05 respectively). Because ethanol had no effect on the resting level of plasma GH or on the LH response to LRF, we suggest that ethanol exerts these effects on a suprapituitary site.
Studies on the Renal Uptake of Vitamin D3 in the Mouse and the Quail
Authors: Dencker Lennart , Tjälve Hans
Published: December 2008

The renal uptake of labelled vitamin D3 was studied in the mouse and the quail. Upon the administration of labelled vitamin D3 autoradiographic experiments showed a specific accumulation of radioactivity in the proximal tubuli of the mouse kidney. This was still obvious 18 days after the administration. In the quail, on the other hand, the uptake in the kidney did not exceed the level of the blood. In the mouse there was a slow increase in the amount of steroid in the kidney after the injection of vitamin D3, a maximum being reached 24 hours after the administration. The amount of steroid which accumulated in the kidney was largely proportional to the injected dose of the vitamin—from doses at 4.8 ng to 4.8 μg. Column chromatography showed that most of the renal vitamin D3 was present in a non‐metabolized form. Cellular fractionation showed that most radioactivity in the kidney was present in the mitochondrial and microsomal fractions. Upon sonication of the fractions most radioactivity was still bound to these particles.
A Method for the Continuous Study of Net Water Transport in the Feline Small Bowel
Authors: Jodal Mats , Hallbäck Dan‐Axel , Svanvik Joar , Lundgren Ove
Published: December 2008

A new perfusion technique has been developed for the study of net water transport across the intestinal epithelium in vivo. The lumen of an isolated intestinal segment is steadily perfused with a solution of known composition in a closed perfusion system with a reservoir large enough to prevent recirculation. The intestinal segment may be enclosed in a plethysmograph. Changes in the perfused volume is recorded by a volume transducer coupled to the recirculating system via a T‐tube. If no motility occurs, the changes of the perfusion volume reflects net water transport across the intestinal epithelium. A quantitative comparison of this technique with the convention polyethylene glycol method revealed no significant difference. The plethysmographic method also makes it possible to quantify the net water absorption via lymph and blood.
Acylation of Carnitine and Glycerophosphate in Suspensions of Rat Liver Mitochondria at Varying Levels of Palmitate and Coenzyme A
Authors: Borrebæk B.
Published: December 2008

Rates of acylation of carnitine and glycerophosphate in suspensions of isolated rat liver mitochondria were measured at varying levels of palmitate and coenzyme A in the presence of ATP. Addition of glycerophosphate caused considerable reduction in carnitine acylation at low, but not at high palmitate levels. Glycerophosphate acylation was less reduced by added carnitine. These results can be explained by a lower Km(acyl‐CoA) in glycerophosphate acylation than in carnitine acylation. High levels of free coenzyme A caused inhibition of carnitine acylation, while the inhibitory effect of glycerophosphate acylation was small. Competition between palmitate and acyl‐CoA for binding sites on protein (e.g., albumine added to the mitochondrial suspensions) was indicated by stimulation of carnitine acylation by palmitate with palmityl‐CoA added as substrate in the absence of ATP. Refeeding a carbohydrate‐rich diet to previously fasted rats resulted in increased glycerophosphate acylation and decreased carnitine acylation in isolated liver mitochondria.
Vascular Resistance in Peripheral Blood Vessels at Normotension and at Local Orthostatic Hypertension in Healthy Humans
Authors: Paaske William P. , Henriksen Ole
Published: December 2008

The effect of changes in orthostatic pressure on vascular resistance in subcutaneous adipose tissue was examined in the forearm at normal tension and in the leg at local orthostatic hypertension in three normal subjects. Blood flow in subcutaneous tissue was measured by the local xenon‐133 washout technique. Changes in orthostatic pressure were achieved by postural changes of the extremity. At levels above the heart where venous pressure is constant, there was autoregulation of blood flow over a wider arterial blood pressure range in leg than in forearm. When transmural pressure increased 25 mm Hg or more vascular resistance increased about 50 per cent in the dependent forearm and 300 per cent in the dependent leg. The effect of ischemia on vascular resistance was investigated in cutaneous tissue of hand and foot by means of the131I‐Antipyrine initial slope technique. Vascular resistance after maximum dilatation achieved after20, 30, and 35 min of ischemia was less in vessels of the hand than in vessels of the foot. Thus, adaptive structural changes of vessels subjected to increased blood pressure are present in cutaneous and subcutaneous adipose tissues in normal subjects.
Effect of Bulbar Acidification on Basal Secretion of Acid and Gastrin in Dog
Authors: Nilsson Goran
Published: December 2008

Dogs were provided with mucosal septal pouches of the stomach and of the duodenal bulb. In some dogs a drainage gastric cannula was inserted into the most dependent portion of the stomach. In dogs which were found to secrete acid spontaneously during a control period at the start of each experiment, the bulbar pouches were perfused with 0.1 M HCl for 5–120 min. Bulbar acidification rapidly and profoundly reduced the basal acid output. In dogs which did not secrete acid spontaneously during the control period bulbar pouches were perfused with 0.1 M HCl for 1 h. Bulbar acidification did not significantly influence the plasma gastrin concentration and no acid was secreted from the Pavlov pouches following such acidification. The present results support the hypothesis that reduction of the intrabulbar pH may contribute to the reduction of acid secretion during interdigestive periods. The physiological significance of mechanisms in the upper intestine which induce acid secretion following a reduction of the intraluminal pH is questioned.
Evidence for a Glucocorticoid Receptor in Human Leukocytes
Authors: Simonesson B.
Published: December 2008

The glucocorticoid uptake in vitro by human periferal leukocytes was studied. The uptake showed 2 main components, one saturable and one non‐saturable. The saturable component was compared with the uptake by the specific glucocorticoid receptor in rabbit granulocytes. The similarities with the rabbit receptor in structural specificity, time course of uptake at 37° C, sensitivity to metabolic inhibition by PCMS and the physiological concentration for half saturation indicate that the saturable component corresponds to a specific glucocorticoid receptor. Cells from chronic lymphatic leukemia and chronic myeloic leukemia were also studied. Only the former had a saturable glucocorticoid uptake.
In VitroUptake of 5‐Hydroxytryptamine and Dopamine by Rat Mast Cells after Exocytosis Induced by Antigen or Compound 48/80
Authors: Guschin Igor S. , Uvnas Börje
Published: December 2008

Mast cells from the peritoneal and pleural cavities of actively sensitized rats were isolated and incubated with biogenic amines (5‐hydroxytryptamine and dopamine) with or without pretreatment with specific antigen. An anaphylactic reaction resulting in the release of 20–25% of the histamine in the cells led to a slightly reduced amine uptake. At concentrations which induced histamine release comparable to that during the anaphylactic reaction compound 48/80 had a similar effect on the uptake of the two amines. Histamine release induced by higher concentrations of compound 48/80 led to a more pronounced reduction in the uptake of the amines, the reduction being roughly proportional to the extent of the histamine release. It is concluded that the reduction in thein vitroamine uptake after anaphylactic and compound 48/80‐induced histamine release is due to the fact that there are a fewer intact granules capable of storing histamine and not primarily due to a damage to the mechanisms by which mast cells take up biogenic aminesin vitro. The observations further strengthen the view that anaphylactic and compound 48/80‐induced histamine release are non‐cytolytic processes.
Effect of Strength Training on EMG of Human Skeletal Muscle
Authors: Thorstensson A. , Karlsson J. , Viitasalo J. H. T. , Luhtanen P. , Komi P. V.
Published: December 2008

The effects of an 8 weeks period of systematic progressive strength training on the EMG activity of the leg extensor muscles (vastus lateralis and rectus fernoris) were investigated in 8 healthy male subjects (22–31 yrs). After training there were indications (n.s.) of a decline in integrated EMG (IEMG) during maximal isometric knee extension as well as in the IEMG vs isometric force relationship. The averaged motor unit potential (AMUP) did not demonstrate any significant changes due to the strength training regimen. In conformity with earlier findings no or only minor alterations were observed in anthropometrics, muscle enzyme activities and fibre composition. The fibre area ratio indicated a specific effect of the training stimuli on the fast twitch muscle fibres. Thus, EMG‐analyses, as employed in the present study, did not provide any conclusive additional explanation as to the mechanisms behind the well established gains in niuscle strength performance induced by the applied strength training program.
Cerebral Utilization of Glucose, Ketone Bodies and Oxygen in Starving Infant Rats and the Effect of Intrauterine Growth Retardation
Authors: Dahlquist Gisela
Published: December 2008

Cerebral arteriovenous differences of acetoacetate, D‐β‐hydroxybutyrate, glucose, lactate and oxygen and brain DNA content was measured at 20 days of age in intrauterine growth retarded (IUGR) rats and normal littermates after 48 and 72 h of starvation. Cerebral blood flow (CBF) was measured with labeled micro‐spheres in other comparable groups of IUGR and control rats. CBF was similar in IUGR and normal littermates (0.57±0.09 and 0.58±0.10 ml/min respectively). After 48 h of starvation, arterial glucose was significantly lower in IUGR than control animals but the arterial concentrations of ketone bodies were similar. After 48 h of starvation, cerebral arteriovenous difference of β‐hydroxybutyrate was significantly higher in control than IUGR rats also when expressed per mg brain DNA as was the fractional uptake of D‐p‐hydroxybutyrate. After 72 h of starvation, arterial concentrations of ketone bodies were significantly lower in IUGR rats than controls but the fractional uptake of D‐β‐hydroxybutyrate was increased compared to IUGR rats starved for 48 h. The average percentage of calculated total substrate uptake (μmol/min) accounted for by ketone bodies increased in control animals from 31.1 % after 48 h of starvation to 41.0% after 72 h of starvation. In IUGR rats these percentage values were 26.5 and 25.7 respectively. After 72 h of starvation the fraction of total cerebral uptake of substrates accounted for by ketone bodies was significantly higher in control than IUGR rats. As total cerebral uptake of substrates was similar between IUGR and control animals it is concluded that IUGR rats are more dependent on glucose as a substrate for the brain during starvation.
Cerebral Metabolic State after Discontinuation of Nitrous Oxide Supply in Artificially Ventilated Rats
Authors: Berntman Leif , Carlsson Christer , Hägerdal Macnus , Siesjö Bo K.
Published: December 2008

Previous results from this laboratory have shown that when administration of 70% nitrous oxide is discontinued in artificially ventilated rats, cerebral oxygen uptake increases by about 40 % at 5 min and by about 80–905; at 30 min, and that this increase is blocked by previous adrenalectomy. In the present experiments, nitrous oxide was withdrawn for 45 s, 2 min 45 s, or 15 min, in non‐adrenalectomized animals. and for 5 min in adrenalectomized animals, and the tissue was frozen in situ for subsequent measurements of labile phosphates, glycolytic metabolites, citric acid cycle intermediates and associated amino acids, and ammonia. The results allow the conclusion that upon withdrawal of nitrous oxide in non‐adrenalectomized animals, there is an increase in metabolic rate at an essentially unchanged metabolic state. In adrenalectornized animals, discontinuation of nitrous oxide supply did not induce changes in any of the tissue metabolites measured. We conclude that 70% N2O neither influences the metabolic rate of the tissue, nor its metabolic state.
A Method for Preparing Isolated Glands from the Rabbit Gastric Mucosa
Authors: Berglindh Thomas , ÖBrink Karl Johan
Published: December 2008

A method for isolating gastric glands from the corpus of the rabbit gastric mucosa is presented. The stomach of an anesthetized rabbit was perfused with saline under high pressure through the aorta, taken out and emptied. The mucosa was stripped off, minced into small pieces and transferred to a 1 mg/ml collagenase solution. After 90 min at 37°C, a large number of isolated gastric glands and cells were separated free. By a simple washing procedure the glands were freed from cell contamination and collagenase. The gastric glands were viable, as demonstrated by dye exclusion technique, oxygen consumption and electrolyte content. For identification of the glandular cells both common staining techniques and electron microscopy were used. Four types of cells were identified, viz. parietal cells, zymogen cells, mucous neck cells and some endocrine cells. The intracellular morphology of the glandular cells did not differ significantly from that seen in intact gastric mucosa. The glands could be stimulated with histamine, in a dose‐response manner, as revealed by the increase in oxygen consumption (ED‐50 equal 3 × 10‐6 M). This isolated gastric gland preparation may serve as a useful tool for new approaches in gastric physiology.
Beta Adrenergic Dilator Component of the Sympathetic Vascular Response in Skeletal Muscle Influence on the micro‐circulation and on transcapillary exchange
Authors: Lundvall Jan , Järhult Johannes
Published: December 2008

A neurogenic β‐adrenergic vasodilatation in skeletal muscle has been indicated by some recent investigations. The present study describes the extent to which this neurogenic β‐dilator mechanism contributes to the integrated vascular response in consecutive sections of the muscle vascular bed during sympathetic nerve activation. This was done by studying the vascular reactions to graded sympathetic stimulation (1–16 Hz) before and after β‐adrenoceptor blockade, β‐blockade did not influence significantly the sympathetically induced changes of total muscle vascular resistance or capacitance. Vascular tone in the “micro‐vessels” during stimulation was, however, clearly more pronounced in the β‐blocked than in the non‐blocked region, as revealed by segmental resistance analysis and by determination of precapillary sphincter tone (CFC). In addition, β‐blockade markedly reduced the net transcapillary absorption of extravascular fluid evoked by nerve activation. This effect could be ascribed to the mentioned influence on the precapillary sphincters, leading to a decrease of the number of capillaries available for transcapillary exchange, and to a limitation of the nerve induced fall of capillary hydrostatic pressure. The described effects of β‐blockade were observed at all rates of sympathetic stimulation. — The conclusion was reached that the β‐adrenergic dilator component of the sympathetic vascular response in skeletal muscle significantly modifies the α‐adrenergic constriction in the micro‐vessels. It is suggested that, in the intact organism, this neurogenic β‐dilator mechanism is primarily aimed at improving the transcapillary exchange.
Disturbances in Voluntary Recruitment Order of Low and High Frequency Motor Units on Blockades of Proprioceptive Afferent Activity
Authors: Grimby Lennart , Hannerz Jan
Published: December 2008

The voluntary recruitment order of anterior tibial motor units was studied in electromyographic recordings using both low and high impedance electrodes. It was shown in previous papers, that the recruitment order in sustained voluntary contraction is normally stable and that motor units with low thresholds discharge at low, regular frequencies and that motor units with high thresholds discharge at higher and more irregular frequencies. In this paper the consequences for the discharge properties of reduced afferent inflow in sustained voluntary contraction were studied, using partial ischemic or lidocain blockades of the muscle nerve and local cooling of the muscle belly. 1. The recruitment order of certain low and certain high frequency units was reversed. 2. The muscle tension and sense of effort necessary for tonic firing were increased for certain low frequency units but decreased for certain high frequency units. 3. On severe reduction of the afferent inflow, the differences in discharge pattern between low and high frequency units were decreased. It is concluded that the recruitment of low frequency units before high frequency units in sustained voluntary contraction is partly due to proprioceptive afferent activity favouring low frequency units and disfavouring high frequency units. It is also concluded that the afferent inflow is involved in restricting certain units to low frequency discharge and others to high frequency discharge.
Regional Distribution of Blood Flow in Calf Muscles of Rat during Passive Stretch and Sustained Contraction
Authors: Wisnes A. , Kirkebø A.
Published: December 2008

The regional distribution and number of microspheres in the calf muscles of rat has been studied during isometric sustained contraction and in stretched uncontracted muscles in situ. Carbonized microspheres, 15 ± 5 μm, were injected into the aortic arch and muscle blood flow arrested 6 sec later. The calf muscles were freeze sectioned (12 slices of 40μm) and the microspheres counted microscopically. The microsphere concentration in the gastrocnemius and plantaris muscles during rest was 4.6 ± 1.6 spheres/mm3 (mean ± S.E.). One min after a standardized exercise programme the sphere concentration was increased to 20.5 ± 3.9 spheres/mm3. At increasing force of contraction following the standard exercise programme, the microsphere concentration fell from 11.6 ± 2.5 at 25% of maximal force of contraction (MFC) to 2.2 ± 0.6 spheres/mm3 at 100% MFC (5.6 kg/cm2). Corresponding measurements in stretched, uncontracted muscles showed a similar fall in microsphere concentration when stretch was increased from 50 to 175% MFC. The ratio between microsphere concentration in the central inner zone and in the peripheral outer zone was slightly higher than unity (1.08‐1.16) in muscles at rest and at light postexercise hyperemia. At 75 and 100% MFC the ratio was 0.76 ± 0.07 and 0.57 ± 0.13, significantly lower than unity. Stretching of the uncontracted muscle group to 175% MFC reduced the ratio towards zero. The greater reduction in blood flow to the inner central zone of contracted calf muscles shown by microsphere distribution was confirmed by measurement of 125I‐antipyrine distribution. These results show an increased resistance against blood flow during active contraction or stretching of the calf muscles, most pronounced in the central inner zone at high tensions.
Effects of Lesions in the Parabrachial Nucleus on the Mechanisms for Central and Reflex Termination of Inspiration in the Cat
Authors: Euler C. von , Marttila Irja , Remmers J. E. , Trippenbach Teresa
Published: December 2008

The effects of PCO2 and body temperature on the time course and peak amplitude of the central inspiratory activity (CIA) and the inspiratory ‘off‐switch’ threshold was studied in apneustic and non‐apneustic cats. Apneusis resulted from lesions of the inspiratory inhibiting structures of the medial parabrachial nucleus (NPBM) and by interrupting vagal volume feedback. The cats were paralyzed and ventilated either proportionally to their phrenic output or at predetermined rate and volume. The dependence of the rate of rise and maximal amplitude of phrenic activity on PCO2, and body temperature were comparable in apneustic and non‐lesioned animals. The Hering‐Breuer volume threshold for inspiratory termination was increased following the rostral pontine lesions. Both hyperthermia and hypercapnia caused augmentation of the absolute rate of rise of inspiratory activity but hypercapnia, in contrast to hyperthermia, caused virtually no change in the fractional increment per unit time. With hypercapnia the inspiratory ‘off‐switch’ threshold was raised in the apneustic animals as in intact ones, whereas hyperthermia did not seem to influence this threshold. In apneustic conditions expiratory duration remained constant, independent of the large variations in the inspiratory durations. Our results suggest that the NPBM merely provides an excitatory, threshold‐lowering input to the inspiratory ‘off‐switch’ mechanism.