bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diamine Oxidase in Blood Plasma in Some Vertebrates and Anodonta cygnea before and after Injection of Heparin
Authors: Hansson Roy , Thysell Hans 
Published: December 2008

AbstractAfter intravenous injection of heparin (in aniounts related to the body‐weight) thc blood plasma diamine oxidase(DAO‐) activity increased transiently in all vertebrates studied (cod, frog, fowl, mouse, white rat, golden hamster, guinea‐pig, rabbit, cat, dog, goat, sheep and cow). The DAO‐response to heparin varied strongly between the species. Often with a bi‐phasic ascent, it showed a maximum (within a few minutes to about one hour) and then decreased, often in a “monoexponential” fashion, in the course of the next few hours. In anodons no significant DAO‐activity was found.—The biological significance of the heparin effect upon DAO is discussed with special reference to the coexistence of heparin and histamine in the mast cells.
The Effect of Nerve Stimulation on the Uptake of Noradrenaline into the Adrenergic Nerve Terminals
Authors: Häggendal Jan , Malmfors Torbjörn 
Published: December 2008

AbstractIn rats pretreated with reserpine and nialamide the effect of sympathetic stimulation, 20 and 6 imp/sec, on the uptake of exogenous noradrenaline was studied in the adrenergic nerves of the iris and salivary glands using fluorescence and biochemical methods, respectively. The uptake of noradrenaline was smaller on the stimulated than on the unstimulated side. The results are discussed with respect to factors such as changes in the circulation, transmitter release during the stimulation, and the presence of an intermittent blockade of the membrane pump during the impulses. It is suggested that the latter mechanisms might be of some physiological importance.
Inhibitory Processes in Gustation
Authors: Hellekant Göran 
Published: December 2008

AbstractDifferent salt and acid solutions were applied in pairs with a short intervening water rinse to the tongue of the cat while the summated chorda tympani nerve response was recorded. It was observed that the first exposure usually depressed the response to the following one. The magnitude of the depression varied and depended on the solutions used. In general K2SO4 and Li2SO4 caused the strongest depression, while MgCl2 and NaCl were most depressed. However, no substance was entirely inert in affecting the response to the second stimulus or was always unaffected by being the second. The results were discussed and subjected to comparison with earlier results. They were interpreted as being influenced by at least three different mechanisms.
Oxygen Toxicity in Nitrogen Mixtures
Authors: Almqvist H. , Jr. M. Arborelus , Barr P. O. , Jansson B. , Kaijser L. 
Published: December 2008

Abstract3 groups of 20 mice were exposed to 4 atmospheres oxygen partial pressure with pure oxygen or nitrogen mixtures, containing 63 or 45% oxygen. The time was measured for the first 10 oxygen fits and for 50% of the animals to become unconscious. With both parameters, if anything, nitrogen seemed to decrease the sensivity of the mice for oxygen poisoning. Provided interspecies differences do not exist, this would imply that decompression‐free diving down to 23 m would be possible. The reasons are discussed for failures in earlier trials to decrease nitrogen partial pressure by adding oxygen to the breathing medium during diving.
Some Studies on the Mechanism by which d‐Amphetamine Antagonizes Guanethidine Induced Adrenergic Neurone Blockade
Authors: Obianwu Hopé O. 
Published: December 2008

AbstractElectrical stimulation of the sympathetic trunk elicited contraction of rat lower eyelid. This response was greatly reduced or abolished by guanethidine (15–25 mg/kg, s.c.) within 30–40 min. Infusion of d‐amphetamine, 0.5 mg/kg, greatly antagonized the blockade within 30–60 min. Amphetamine similarly administered to control animals potentiated the response of the eyelid to nerve stimulation and tyramine. After inhibition of MAO, amphetamine still enhanced the response to tyramine and nerve stimulation. Potentiation of the response to nerve stimulation did not appear to be due to inhibition of reuptake process since this effect was still observed after protriptyline treatment, a substance which is about twenty times as active as amphetamine in this respect. It is suggested that the ability of amphetamine to potentiate the response to nerve stimulation may be an important factor in its antagonism of guanethidine‐induced nerve blockade.
Formation of Extracellular Adenosine Triphosphate by Tumour Cells
Authors: ÅGren Gunnar , Ronquist Gunnar 
Published: December 2008

AbstractThe formation of extracellular ATP by Ehrlich ascites tumour cells and HeLa cells was studied. The tumour cells were incubated with the substrates, including 32P‐labelled inorganic phosphate, and cofactors of the glyceraldehyd‐3‐phosphate dehydrogenase and phosphoglycerate kinase reactions (complete system), as well as with an incomplete system lacking ADP, NAD+ and glyceraldehyde‐3‐phosphoric acid. All incubations were performed under isotonic conditions. After 1 min incubation of tumour cells, an 8‐fold increase in the 32P‐labelled ATP took place with the complete system, compared with the incomplete system. All the (32P)ATP formed as a consequence of the presence of the phosphorylated substrates and cofactors in the complete system could be recovered in the extracellular medium. No measurable leakage of intracellular (32P)ATP into the extracellular medium occurred. The extracellular medium did not contain significant amounts of solubilized enzymes responsible for the extracellular formation of (32P)ATP. The presence of intact tumour cells during incubation was necessary for the main part of (32P)ATP to be formed. It is therefore concluded that most of the (32P)ATP present in the extracellular medium was formed by enzymes located on the surface of the tumour cells.
The Effects of Extracellularly Applied ATP and Related Compounds on Electrical and Mechanical Activity of the Smooth Muscle Taenia Coli from the Guinea‐Pig
Authors: Axelsson Johann , Holmberg Bo 
Published: December 2008

AbstractThe effect of external ATP and related compounds on the electrical and mechanical activity of isolated pieces of taenia coli has been studied. ATP, AMP and adenosine caused a decrease in the spontaneous tone, a decrease in the frequency of spike discharge, and hyperpolarization. ATP was up to 100 times as potent an inhibitor of spontaneous activity as AMP or adenosine. GMP, guanosine and inosine had no effect. High K+ contractures were relaxed by the same compounds and adenine, which was the most potent. Here again GMP, guanosine and inosine had no effect. ATP, AMP and adenosine prevented or shortened the initial depolarization produced by acetylcholine and carbachol. Inorganic phosphate was liberated from ATP and AMP applied to the bathing solution. The hydrolysis was not significantly decreased by g‐strophanthin. p‐Hydroxy‐mercuribenzoate caused an initial excitation as well as g‐strophanthin but neither inhibited the relaxing effect of ATP. The effects of extracellularly applied ATP are consistent with the view that they are exerted through changes in membrane permeabilities and that some of these effects are brought about by the adenosine part of the molecule.
Blockade of the PhosphorylaseaActivating Effects of Catecholamines and Adenosine 3‘,5’‐Monophosphate (Cyclic AMP) in High K+ or Choline Buffer Media
Authors: Lundholm Lennart , Mohme‐Lundholm Ella , Vamos Nandor 
Published: December 2008

AbstractIn isolated rat diaphragm suspended in a buffer solution where Na+ had been exchanged for K+ or choline the basal phosphorylaseaactivity was reduced and the phosphorylaseaactivating effect of adrenaline and isoprenaline was blocked or reduced. The total phosphorylase activity and the level of high energy phosphate compounds were unchanged in high‐K+ buffer but the former reduced in choline buffer. The basal phosphorylaseaactivity was reduced in a Ca++‐free solution but the effect of adrenaline was unchanged. The phosphorylaseaactivating effect of the catecholamines is mediated by adenosine 3′,5′‐monophosphate (cyclic AMP). Addition of cyclic AMP to the buffer solution had a stimulating effect on the phosphorylaseaactivity of the rat diaphragm. This effect was blocked or reduced when Na+ in the buffer solution was exchanged for K+ or choline. It has been demonstrated that the stimulating effect of adrenaline on the cyclic AMP content in the diaphragm is unchanged in high‐K+ media. We suggest that the blockade of the phosphorylaseaactivating effect of the catecholamines in high‐K+ media was due to an inhibition of the action of cyclic AMP.
The Effects of Hypercapnia and Hypocapnia upon the Cerebrospinal Fluid Lactate and Pyruvate Concentrations and upon the Lactate, Pyruvate, ATP, ADP, Phosphocreatine and Creatine Concentrations of Cat Brain Tissue
Authors: Granholm Lars , Siesjö Bo K. 
Published: December 2008

AbstractThe lactate and pyruvate concentrations in cisternal cerebrospinal fluid (CSF), and the lactate, pyruvate, ATP, ADP, phosphocreatine, and creatine concentrations in brain tissue were measured in cats during hyper‐ and hypocapnia. (PaCO2 10–100 mm Hg). Both the CSF and the tissue concentrations of lactate and pyruvate varied inversely with the arterial CO2 tension. In hypercapnia the tissue lactate/pyruvate ratio increased in accordance with a theoretical curve, calculated for a pH dependent equilibrium between the lactate/pyruvate and the NADH/NAD+ systems. In hypocapnia, however, there was no corresponding decrease in the CSF and tissue lactate/pyruvate ratios but a progressive increase at arterial CO2 tensions below 25–20 mm Hg. The inter‐pretation of these results, which indicate the presence of tissue hypoxia at such low CO2 tensions, were complicated by the presence of unchanged tissue levels of ATP and phosphocreatine. The results also showed that in hypocapnia, pyruvate, but not lactate, was distributed between the extra‐ and intracellular spaces according to the pH gradient, while in hypercapnia, lactate, but not pyruvate, had this distribution. The similarity of the changes in CSF and tissue lactate and pyruvate concentrations lend further support to the assumption that the CSF lactate/pyruvate system reflects cellular redox states.
Tubular Sodium Reabsorption and the Regulation of Renal Hemodynamics. The Effect of Chlorothiazide on Renal Vascular Resistance
Authors: Aperia Anita C. 
Published: December 2008

AbstractIn hydropenic dogs under Nembutal anesthesia chlorotiazide, in parallell with its inhibition of distal tubular Na reabsorption, caused a marked increase in renal vascular resistance and a decrease in total renal blood flow and glomerular filtration rate. The renal vasoconstriction appeared to be both pre‐ and post‐glomerular, since the glomerular filtration rate was reduced in proportion to the total renal blood flow. The vasoconstriction could not be abolished by sympathetic blockade (Dibenzylene). During ureteral obstruction, when formation of glomerular filtrate could be regarded as minimal despite of unimpaired renal blood flow, the vasoconstrictive response to chlorothiazide was much reduced. This excludes a direct constrictive effect of chlorothiazide on the renal vascular bed. The constrictive response of the renal vascular bed was found to be correlated with the inhibition of Na reabsorption rather than with increase in urine flow. The data are interpreted as supporting the hypothesis that Na transfer in the distal tubule is one important mechanism for controlling renal vascular tone. a control that may be mediated by the renin angiotensin system. It is further suggested that the important factor is the intracellular Na concentration in the first part of the distal tubule. lather than intratubular concentration as such at this site. Contrary to previous interpretation the present observations suggest that it is a decrease in Na transfer, rather than an increase, that is directly or indirectly involved.
Effects of Hyperosmolarity on the Volume of Vascular Smooth Muscle Cells and the Relation between Cell Volume and Muscle Activity
Authors: Arvill Anders , Johansson Börje , Jonsson Olof 
Published: December 2008

AbstractElectrical and mechanical responses of vascular smooth muscle to variations in extracellular osmolarity were analysed in a previous study using isolated preparations of rat portal vein (Johansson and Jonsson 1968). The purpose of the present investigation has been to measure the changes in the volume of the cells of this smooth muscle when exposed to hyperosmolarity and to elucidate further the previously postulated relation between cell volume and muscle activity. Distribution of water, urea‐14C and sucrose‐14C in the isolated portal vein has been determined. Urea‐14C rapidly equilibrates in a volume of 77.9 ml/100 g wet tissue weight which agrees satisfactorily with the total water content of the muscle (79.0 ml/100 g). The smooth muscle cells thus show a high membrane permeability for urea. When the muscle is incubated in isoosmotic Krebs solution the distribution volume of sucrose‐14C reaches 45.4 ml/100 g within 15 min and then increases very slowly to 49.4 ml/100 g within 120 min. The former value has been taken to represent the extracellular space. After 20 min in a hyperosmotic medium (normal Krebs solution +150 mmoles sucrose/l) there is a decrease of total wet tissue weight to approximately 86 per cent of the control value and, simultaneously, a relative increase of extracellular space from 45.4 to 48.5 ml/100 g. Calculations show that the intracellular fluid volume has then decreased by about 34 per cent indicating an almost perfect osmotic behaviour of the smooth muscle cells in response to hyperosmolarity of this degree. The changes in muscle activity observed during and after exposure to hyperosmotic urea‐ and sucrose‐Krebs solutions are discussed in the light of the changes in cell volume and the time course of the uptake of urea‐14C and sucrose‐14C. The present results support the existence of a relation between cell volume and activity in vascular smooth muscle.
Catechol‐O‐Methyltransferase in Autonomic and Sensory Ganglia of the Cat
Authors: Giacobini Ezio , Kerpel‐Fronius Sandor 
Published: December 2008

AbstractCatechol‐o‐methyltransferase (COMT) activity was determined in normal and preganglionically denervated sympathetic ganglia as well as in parasympathetic and sensory ganglia of the cat by means of the micro‐radiochemical method of McCaman (1965). Low levels of COMT activity were found to be present in all three types of investigated ganglia. In the sympathetic ganglia the COMT activity was almost evenly distributed. No correlation could be demonstrated between COMT activity, monoamine oxidase (MAO) activity and the reported catecholamine content in the various sympathetic ganglia. Preganglionic denervation of sympathetic ganglia did not significantly change the enzyme activity. The results indicate that in the autonomic ganglia COMT is confined neither to presynaptic structures nor to “adrenergic” neurons.
Unit Responses in the Rat Cochlear Nucleus to Repetitive, Transient Sounds
Authors: Møsller Aage R. 
Published: December 2008

AbstractThe response patterns are described of cochlear nucleus units (termed rat transient units) which only responded to a tone burst with a single discharge evoked immediately after the onset. When these cells were stimulated with bursts of repetitive clicks such units showed a marked selectivity to the click repetition rate. At a low click repetition rate one discharge was evoked for each click but this one to one relationship failed rapidly when the click rate was increased slightly above a given click repetition rate. Any additional increase in click rate resulted in only a single discharge fired immediately after the onset of a click burst and thus resembling these units' response to tone bursts. By replacing the click sounds by short bursts of pure tones presented repetitively it was shown that rat transient units were not selective to repetition rate per se, but rather, to the duration of silent interval between successive sounds. The activity of these units to click stimulation could be inhibited by broad band noise or by pure tones within certain frequency limits. Furthermore, these units showed a spectral selectivity which appeared when the stimulation was pure tones or band‐pass filtered clicks. The spectral region of highest sensitivity varied among the individual units in the range from 5 to 20 kHz and was thus widely different from the critical repetition rate for click stimulation. The latter rate was found to vary from 200 to 800 clicks per second in different units.These findings may thus explain why, in psychoacoustic experiments, repetitive presentation of short sounds results in a pitch perception which is dependent on the length of the silent period between successive sounds.
An Electromyographic Analysis of Muscular Activity in the Hindlimb of the Cat during Unrestrained Locomotion
Authors: Engberg I. , Lundberg A. 
Published: December 2008

AbstractDuring walking in unrestrained cats the electromyographic activity in many hindlimb muscles has been correlated with the angular movement in the hip, knee and ankle joints. The activity is rather uniform in the extensors but individual in different functional groups of flexor muscles. Observations on the precise timing of the onset of the main extensor activity suggest that it is not a reflex effect produced by stimulation of receptors (from muscle or skin) in the limb. It is assumed that the basic activity is a centrally programmed alternating activation of extensors and flexors. A possible reflex regulation mainly from la afferents of this basic activity is discussed with special attention given to factors that may elucidate the difference in movement at the hip on one side and the knee and ankle on the other.
Histochemical Studies on the Metabolism of L‐DOPA and Some Related Substances in the Exocrine Pancreas
Authors: Alm P. , Ehinger B. , Falck B. 
Published: December 2008

AbstractThe turnover of L‐DOPA and some related substances was studied with the fluorescence method of Falck and Hillarp. All the amino acids injected were easily taken up by the pancreas. This, however, was not the case with the corresponding amines. Only after L‐DOPA and DA administration, fluorescent granules could be seen in the apical zones of the exocrine cells. These granules were found to be identical with the zymogen granules. Decarboxylase inhibition prevented and MAO and COMT inhibition prolonged the appearance of the fluorescent granules. This indicates, that the fluorescent products stored in the zymogen granules is dopamine rather than DOPA.
Response of Isolated Muscle Spindles of the Frog to Sinusoidal Changes in Length
Authors: Jahn Samia Al Azharia 
Published: December 2008

AbstractThe response of isolated muscle spindles of the frog to sinusoidal vibrations was studied by subjecting the preparation to deformations of 0.15–1 mm at frequencies of 40–200 Hz. The minimum stretch required to evoke an afferent action potential in each cycle of deformation increased with frequency and reached level at 150–180 Hz. This increase was shown to be due to the visco‐elastic properties of the muscle spindle, the stiffness of the equatorial region increasing with the frequency of vibration. With an initial stretch of the “resting” spindle of 10–15 per cent and a frequency of vibrations of 120–160 Hz, one response in each cycle was evoked by displacements of the equatorial region which were the same as the threshold (T) for single stretches. Vibration at lower or higher frequencies required displacements of 1.5– 2 × T. When the initial stretch was 20–25 per cent the displacement of the equatorial region required to elicit an afferent response in each cycle was 1.5 × T at 120–160 Hz, 3 × T at 60– 80 Hz and 2–3 × T at 200 Hz. The change in threshold with frequency was similar in isolated muscle spindles to what has been described by others in Pacinian corpuscles.
The Role of Adenine Nucleotides in the Peripheral Vasodilating Effect of Thrombin
Authors: Olsson Per , Swedenborg Jesper , Teger‐Nilsson Ann‐Catrine 
Published: December 2008

AbstractThe experiments were designed to study the mediating mechanism for the previously demonstrated vasodilating effect of thrombin when small amounts are infused into the femoral artery of the dog. Washed blood cells, suspended in physiological saline, were incubated for a short time with small amounts of thrombin. The supernatant from such a cell suspension exerted a highly vasodilating effect when infused into the femoral artery. This vasodilating effect was compared to that of serotonin, histamine, adenosine and adenine nucleotides. Histamine, adenosine and adenine nucleotides caused the same type of reactions as that of vasoactive supernatants. By inactivation experiments, where these substances, as well as vasoactive super‐natants, were heated or incubated with plasma or ADP‐ase–ATP‐ase (Apyrase), it was concluded that the vasodilating agents in the latter are mainly ADP and to some extent ATP.
Dissociation of Histamine Release and22Na+Uptake in Rat Mast Cells Exposed to Compound 48/80 in vitro
Authors: Slorach Stuart A. , Uvnäs Börje 
Published: December 2008

AbstractThe relationship between22Na+uptake by, and histamine release from, rat mast cells exposed to compound 48/80in vitrohas been investigated in order to elucidate the mode of action of this releaser. The time course studies show that22Na+uptake and histamine release both begin after a latent period of about 5 sec but, whereas histamine release is complete after approximately 30 sec,22Na+uptake is not maximal until after 10 min. Assuming that22Na+and23Na+are taken up similarly, we have calculated that the quantity of23Na+taken up was insufficient to replace the amount of histamine released if an intracellular exchange of these two ions was involved. We conclude from these observations that intracellular exchange of sodium for histamine does not play a significant role in histamine release induced by compound 48/80. The large increase in22Na+uptake by mast cells exposed to compound 48/80 can be prevented by pretreating the cells with N‐ethylmaleimide or ninhydrin, which also inhibit the histamine release. We found evidence for the existence of a “sodium pump” mechanism which could be inhibited by ouabain. The histamine liberator d‐tubocurarine also produced an increase in the net22Na+uptake by mast cells but another releaser, n‐decylamine, which produces histamine release by lysis of the cell membrane, did not.
The Dynamics of the Inotropic Change Produced by Altered Pacing of Rabbit Papillary Muscle
Authors: Edman K. A. P. , Nilsson E. 
Published: December 2008

AbstractThe time course of the active state, the force‐velocity relationship and the series compliance of rabbit papillary muscles were studied at different inotropic states produced by altered pacing of the muscles within the range 18 to 72 stimulations per minute. The inotropic intervention produced a shift of the force‐velocity curve, without markedly changing the shape of the curve, suggesting that Vmax, the capacity to produce motion, and Pmaxthe capacity to produce tension, were affected to the same degree. Intensification of the active state in response to an increase in stimulation frequency was associated with a steeper rise of the active state and an earlier attainment of maximum. The series compliance was unaffected by the inotropic intervention. The results are taken as evidence (1) that the two parameters of the active state, Vmaxand Pmax, are governed by a common control mechanism in the excitation‐contraction coupling and (2) that the inotropic effect is due to altered kinetics of this control function. The nature of the mechanism governing the active state is discussed in relation to the slicling‐filament theory of muscular contraction.