bluuebunny/crossref_metadata_2025_split huggingface dataset:
Active State Durations of Rat Gastrocnemius Muscle
Authors: Wilander B. 
Published: December 2008

AbstractFor rat gastrocnemius muscle it has been found that: 1. The shortening velocity of an isotonic afterloaded contraction increases with the stimulation frequency up to a frequency of 425 imp/sec, about twice as high as that above which no substantial increase in isometric peak tension occurs. 2. The initial form of the isometric contraction curves for one and for two closely spaced impulses have been found to be consistent with the active state concept of Hill. 3. The duration of the active state plateau after a single impulse, as indicated by the capacity to shorten, is no longer than 1.5 msec. 4. The stimulation interval just necessary for fusion of an isometric tension plateau at 150 msec of stimulation is more than twice as long as the longest possible duration of the active state plateau for shortening after a single impulse. 5. From an analysis of the tension oscillations at stimulation with frequencies somewhat below that necessary for fusion it has been found that the mechanical latency is as short as after the first impulse (0.6 msec). The maximal rate of tension rise after an impulse is, however, considerably delayed, and the implications of this finding are discussed in terms of the active state concept.
Surface Properties of Lung Extracts
Authors: Adams Forrest H. , Enhörning Goran , Norman Anne 
Published: December 2008

AbstractExtracts of rabbit lungs from adult animals as well as from fetuses near term were studied with a dynamic alveolar model and with a modified Wilhelmy balance. With both methods the minimal value of surface tension was significantly higher in the fetal extracts, probably because they have a lower concentration of surface active material. With no change in surface area the extracts from adult lungs after 30 min had a mean surface tension of 41 ± 5 dyn/min. When surface area was compressed the tension decreased and when the surface area was expanded the tension increased. The difference between the mean value and the minimal or the maximal value was a function of change in surface area as well as time. The change in surface area and the rate with which it occurs in the lungs is more closely simulated with the dynamic alveolar model than with the modified Wilhelmy balance. The minimal value of surface tension was recorded at minimal surface area. It increased if surface area was maintained at minimal size. This demonstrates viscosity of the surface film. For alveolar stability the outlining film should probably have high viscosity as well as low surface tension. In the newborn these properties have to develop rapidly to prevent alveolar collapse.
Electrophysiological and Micro‐electrophoretic Studies on Sympathetic Preganglionic Neurones in the Spinal Cord
Authors: Hongo T. , Ryall R. W. 
Published: December 2008

AbstractPreganglionic sympathetic neurones in the thoracic cord of the spinal cat were located by recording antidromic extracellular potentials in response to stimulation of preganglionic fibres in the superior splanchnic nerve. Antidromic potentials were only recorded in the region of the intermedio‐lateral cell column. Few units were firing spontaneously or could be orthodromically activated. The conduction velocities in the preganglionic axons of units from which recordings were obtained ranged from 1.5 to 9 m/sec. Local micro‐electrophoretic applications of DL‐homocysteic acid fired the cells but noradrenaline had no excitatory effect and did not inhibit spontaneous, synaptic or antidromic firing or the firing to the excitant amino acid. Acetylcholine had no effect on the few cells tested.
Afferent Activity Recorded in the Kidney Nerves of Rats By
Authors: ÅStröm A. , Crafoord J. 
Published: December 2008

AbstractIn anesthetized rats no spontaneous afferent activity in the kidney nerves could be recorded. If the renal vein pressure was elevated, or if i.v. infusion of saline or Ringer solution was given, an afferent discharge of a slowly adapting type could be recorded. It is concluded that an adequate stimulus for the mechanoreceptors responsible for this activity is increased kidney tenseness (intra‐renal pressure) and perhaps also distension of the intrarenal veins. The results indicate that more than one kind of fibers are engaged in the afferent activity which can be elicited by various kinds of stimuli.
Augmentation of Tissue‐Blood Transfer of Solutes by Transcapillary Filtration and Absorption
Authors: Lundgren O. , Mellander S. 
Published: December 2008

AbstractThe effect of net transcapillary fluid movement on the rate of transfer of131I,24Na,86Rb and133Xe from tissue to blood was studied in cat skeletal muscle. The technique used permitted control, directly or indirectly, of other factors of importance for exchange, such as blood flow, flow velocity. capillary‐ flow distribution. size of capillary surface area and capillary permeability. Net fluid filtration was produced by raising mean hydrostatic capillary pressure and net fluid absorption by increasing plasma osmotic pressure. It was shown that a net transcapillary fluid movementper se(filtration or absorption) increased the transport rate from tissue to blood considerably above the control level when no net fluid movement occurred (Fig. 3). The rate of solute transfer seemed to increase progressively with the rate of net fluid movement, at least in the lower range. The extent to which transfer increased was roughly the same for all water‐soluble substances studied. While for133Xe net transcapillary filtration appeared to produce a less marked increase in transport rate. Reduction in nutritional blood flow was followed by a decrease in rate of isotope transfer. This decrease proved much smaller when the flow reduction was associated with net transcapillary fluid filtration. The possible physiological significance of transcapillary fluid movements for control of tissue‐blood exchange is tentatively discussed.
Mast Cells and 5‐HT: Uptake of labelled 5‐hydroxytryptamine (5‐HT) and 5‐hydroxytryptophan in relation to storage of 5‐HT in individual rat mast cells
Authors: Ritzén Martin 
Published: December 2008

AbstractThe capacity of individual rat peritoneal mast cells to take up and concentrate radioactively labelled 5‐hydroxytryptamine (5‐HT) and 5‐hydroxytryptophan (5‐HTP) was studied by quantitative cyto‐chemical methods. By means of consecutive application of microfluorometric, autoradiographic and microinterferometric methods, the following parameters could be determined for each cell: 1. Relative amount of endogenous 5‐HT. 2. Concentration of accumulated isotopes. 3. Dry mass. 4. Concentration of endogenous 5‐HT. 5. Total amount of accumulated isotopes. The calculated correlations of these variables to each other showed general heterogeneity of the population, variations between the different cells being very large. However, on the whole, increasing dry mass of the mast cells was accompanied by an increase in 5‐HT content, but with a decrease in concentrations of endogenous 5‐HT and accumulated radioactive 5‐HTP. Similarly, cells having large stores of endogenous 5‐HT showed a higher total uptake, but a lower cellular concentration of exogenous 5‐HT and 5‐HTP, than cells that were poor in endogenous 5‐HT. The results indicated that the uptake of 3H‐5‐HTP was proportional to the total area of the cell membrane, while the degree of 3‐HT uptake was determined by other factors. When the concentrations of radioactivity in the incubation medium was compared to that of the living mast cell, it was found that the averagr cell was able to concentrate exogenous 5‐HTP and 5‐HT around 4 and 30 times, respectively.
Electrical and Mechanical Activity of Human Respiratory Muscles during Voluntary Inspiration
Authors: Viljanen A. A. 
Published: December 2008

AbstractIt has been shown, that in a certain range of inspiration there exists a linear relationship between the total number of electromyogram impulses during inspiration and the first time integral of the muscular inspiratory work of breathing. During one inspiration the number of electrumyogram impulses is increasing in a linear relationship to the pressure impulse.
Insulin Binding Proteins in Normal Serum. Qualitative and Quantitative Studies in vivo in Cats
Authors: Gjedde F. 
Published: December 2008

AbstractAfter iv. infusion of homlogous 125I labelled insulin to cats, the serum radioactivity decreased exponentially and in a logarithmic plot three different slopes were observed. The portion with the steepest slope had a half‐life of from 4 to 8 min and corresponded to the elimination of free insulin.The intermediate portion of the curve was caused by the association of about 18 per cent of the injected radioactivity with an alpha‐one globulin. The half‐life of this complex was 150 min being caused by equilibration of the labelled substance between intra‐and extravascular space. Of this radioactivity associated with the alpha globulin 30 per cent could be precipitated using a double immunoprecipitation for insulin. By electrophoresis on starch block and starch gel the radioactive globulin was characterized as a fast alpha‐one globulin. By gel filtration on Sephadex G 200 it was eluted with the albumin peak. Only 15 per cent of the radioactivity associated with the alpha‐one globulin could be precipitated by 80 per cent saturation with ammoniun sulphate, whereas 100 per cent could be precipitated with trichloroacetic acid.When the radioactive alpha‐globulin was infused into four other cats, it was diluted with a volume corresponding to 4.7 per cent of the body weight; after 24 hrs the space had expanded to a value corresponding to 19 per cent of the body weight. After equilibration, a fall of the protein‐bound radioactivity of serum and an excretion of radioactivity in the urine corresponding to a half life of 50 and 52 hrs was observed.No association of radioactivity with the macroglobulins could be demonstrated in vivo.
The Effect of Thyroidectomy on the Hypothalamus of the Rat with Special Reference to the Hypothalamic‐Hypophyseal Neurosecretory System
Authors: Talanti S. 
Published: December 2008

AbstractWith male adult albino rats for experimental animals, the effects of operative thyroparathyroidec‐tomy and of thyroidectomy accomplished with radioactive iodine on the nuclear volume of the ganglion cells in the nuclei of the hypothalamus were studied. In addition, the amount and distribution of aldehyde‐fuchsin‐positive neurosecretory material under these experimental conditions were studied. The changes were similar in rats ectomized by either procedure. In comparison to untreated control animals, the nuclear volume of the ganglion cells decreased in all nuclei investigated. The change was statistically highly significant in most instances. The amount of neurosecretory material seemed to decrease, on the strength of visual assessment, both in the neurohypophysis and in the median eminence. The depletion of the material in the neurohypophysis could also he demonstrated by photometric measurement. From the results the inference was drawn that a decrease in the activity of the hypothalamus occurs after thyroidectomy. At the same time also the activity of the neurosecretory system goes down, which is reflected by depletion of the neurosecretion. No sharply localized regulatory centre could be shown for the pituitary‐thyroid interplay because the entire hypothalamus reacted in identical manner.
Local Myocardial Blood Flow Measured by Hydrogen Polarography; Distribution and Effect of Hypoxia
Authors: Aukland Knut , Kiil Fredrik , Kjekshus John , Semlb Gudmund 
Published: December 2008

AbstractLocal myocardial blood flow was measured in open chest dogs by polarographic recording of hydrogen desaturation with needlrshaped platinum electrodes. A potential of + 0.3 V relative to a KCl saturated calomel elrctrode was applied to the platinum electrode to minimize oxygen sensitivity. The influence of convection in the medium on electrode current was investigated in vitro. Myocardial hydrogen desaturation recorded with tissue electrodes gave acceptable monoexponen‐tial curves in about 80 per cent of all electrode sites. Possible mechanisms of multi‐exponential curves which were discarded are discussed. Good agreement was obtained between two electrodes in one ventricle and between left ventricular and coronary sinus recordings, and arguments are given that hydrogen clearance equals blood flow in the range of 50 to 450 ml/min 100 g. Myocardial blood flow was on the average 11 per cent lower in the right than in the left ventricle (anterior walls), and this relationship was unchanged during dextran infusion and spontaneous variations of myocardial flow. Right/left flow ratio also remained unchanged when myocardial flow was increased up to four times by hypoxia. The flow rise was such as to maintain or even increase the amount of oxygen delivered to the myocardium of both ventricles.
Muscle Glycogen and Muscle Electrolytes during Prolonged Physical Exercise1
Authors: Ahlborg Björn , Bergström Jonas , Ekelund Lars‐Göran , Hultman Eric 
Published: December 2008

AbstractNine volunteers have been examined during prolonged physical exercise to exhaustion at a load of about 60 per cent of W170. Ordinary circulatory parameters were measured as well as the quantities of glycogen, water and electrolytes in muscle tissue obtained by needle biopsy. In a separate study 6 subjects were examined for respiratory quotient under similar exercising conditions. The muscle glycogen fell considerably from a mean of 6.9 per 100g glycogen and fat‐free solids to a mean of 1.7 g at the end of exercise. The quantity of muscle glycogen used was correlated both to total energy developed during exercise and also to duration of exercise.The electrolyte and water content in muscle tissue showed only small changes. Some increase was found in muscle sodium and chloride, and also in the chloride space. The potassium content fell significantly by about 4 per cent of the basal value. None of the circulatory parameters measured showed changes of such magnitude as to have a limiting effect on performance. Two subjects were examined also with glucose infusion during the exercise. The reduction of glycogen, as also the performance of these two subjects, was of the same order of magnitude with and without infusion of glucose. The results suggest that the capacity for prolonged work is directly correlated to the glycogen store in the working muscles.
Excretion of Sodium and Potassium in Cat Submandibular Saliva
Authors: Petersen Ole Holger , Poulsen Jørges Hedemark 
Published: December 2008

AbstractThe concentrations of ions in the saliva vary with the secretory rate. Different results concerning sodium concentration in relation to flow rate have been found by different investigators. In the present work secretion was elicited by chorda stimulation and the concentrations of sodium and potassiuni in the saliva were determined by flame photometry. The sodium concentrations in the first samples of cat submandibular saliva taken from a previously resting gland were higher than the sodium concentrations in samples taken later at the same secretory rate. The maximal difference in concentration between transient and steady state sample was about 50 meq/l. Steady state concentrations of sodium increased proportionally to the flow rate except at low flow rates where sodium concentrations were greater than expected on the basis of this relation. Steady start concentrations of potassium were independent of the secretory rate when this was higher than 100 μ1/min/g gland, with a value of about 10 meq/l. Below this flow rate the potassium Concentration rose, first slightly and then steeply, when flow rate decreased, and reached values of more than 100 nieq/1 at secretory rates of about 2 μl/min/g gland.
Permeability of Brain Capillaries to Hexoses and Pentoses in the Rabbit
Authors: Agnew W. F. , Crone Christian 
Published: December 2008

AbstractThe initial loss in the rabbit brain of non‐electrolytes injected into the carotid artery was measured with ‘Indicator Diffusion’ technique, 3–0–methyl‐D‐glucose shared with D‐glucose the ability to pass into the brain by a mediated transport mechanism. The rate of transport of the following substances could not be distinguished: D‐mannose, D‐galactose, D‐arabinose and 1)‐ribose. They all penetrated more slowly than D‐glucose.D‐mannitol was also lost from the blood during the passage through the brain. This observation, together with the known inability of D‐mannitol to pass the blood‐brain barrier, suggests that the loss takes place into the endothelial cytoplasma. Thus the basal plasma membrane of the endothrlial cells together with the basal membrane proper may define blood‐brain barrier chararteristirs.
Effect of Prolonged Heavy Exercise on Renal Function and Urinary Protein Excretion
Authors: Castenfors Jan , Mossfeldt Folke , Piscator Magnus 
Published: December 2008

AbstractThe urinary proteins in normal men participating in an 85–kilometre ski race held in 1964 and 1965 were examined by electrophoresis, immunoelectrophoresis and gel filtration. The urinary escretion of protein, glucose, ribonuclease and α‐amino acid‐N was also studied. In conjunction With the 1965 race additional studies were made of urine flow, free water clearance, creatinine clearance sodium, phosphorus and potassium exeretion and examination of urinary sediment. There was a significant increase in total protein and albumin excretion during the race. The protein excretion varied considerably from one individual to another. In 9 subjects who participated in both years the protein excretion, and also the peremtage albumin found by electrophorcsis, showed a significant correlation between the two years. The excretion of glucose and α‐amino acids, which are freely filtrable in the glomerule, was not significantly changed. Sor was the exeretion of the low molecular wright protein, ribonuclease. which may be expected to be almost completely filtrable. This suggests that tubular reabsorption is mainly unchanged during exercise, but that glomerular prmirability for relatively large molecules is increased. Creatinine clearance decreased during the race. Urine flow and sodium exeretion decreased slightly during exercise. Potassium exeretion increased both during and after the ski race. Urinary sediment showed increased amounts of red and white cells, and hyalinc casts.
Recurrent Discharges Studied in Single Units of Laryngeal Muscles
Authors: Mårtensson A. 
Published: December 2008

AbstractIt has previously been shown that electrical stimulation applied to the intact laryngeal inuscle nerves of anesthetized dogs elicits. besides the direct response. also a secondary. centrally relayed response (Mårtensson 1963). The first section of the present paper describes studies of these responses in single units and provides conclusive evidence that the centrally relayed response is not a proprio‐ceptive reflex discharge but represents a recurrent discharge transmitted through antidromically invaded inotoneurons; it is shown that when the direct response consists of a discharge in a single motor unit the secondary response invariably represents a discharge in the same unit. and that the centrally relayed response is transmitted by nerve impulses travelling at the same velocity in the centripetal and centrifugal direction. In the second section of the paper, experimental evidence is presented that the recurrent discharges thus recorded in the laryngeal muscles obey the laws postulated for the generation of such discharges in spinal motoneurons (Eccles 1955).
Myogenic Response of Resistance Vessels and Precapillary Sphincters in Skeletal Muscle during Exercise
Authors: Lundvall Jan , Mellander Stefan , Sparks Harvey 
Published: December 2008

AbstractCapillary filtration coefficient (CFC), reflecting precapillary sphincter tone, and venous outflow of cat lower leg muscle were observed at various transmural pressures before and during muscle work. Increasing transmural pressure in resting muscle 30 mm Hg caused a 35 per cent decrease in CFC, indicating increased tone of precapillary sphincters and, on the average, no change in blood flow, indicating that the increased active tone of resistance vessels closely balanced passive distention. During exercise at 1 twitch/sec, elevating transmural pressure decreased CFC by 50 per cent and increased flow 38 per cent indicating that while precapillary sphincters were still responsive, metabolic demand caused the resistance vessels to behave passively. At 4 twitches/sec the active response of the precapillary sphincters was present, although less marked, whereas the passive behaviour of the resistance vessels was even more pronounced than at 1 twitch/sec. Myogenic autoregulation of filtration exchange via alteration of precapillary sphincter tone may be an important factor preventing gross edema in the legs of upright man during exercise.
Effect of Dihydralazine on Plasma Renin Activity and Renal Function during Supine Exercise in Normal Subjects
Authors: Božović Ljubomir , Castenfors Jan 
Published: December 2008

AbstractPlasma renin activity, clearance of inulin (Cin) and para‐aminohippuric acid (Cpah), urinary sodium and potassium excretion during supine exercise were studied in normal healthy men. 8 subjects were treated during exercise with dihydralazine (Nepresolin® i.v.) and 8 subjects were untreated (control group). In the untreated subjects there was a statistically significant decrease in Cpahand increase in filtration fraction. The decrease in Cparduring exercise was less in the dihydralazine‐treated group and the increase in filtration fraction almost inhibited. Urinary sodium excretion decreased significantly in both groups during exercise but returned slowly to pre‐exercise level in the dihydralazine group. Plasma renin activity increased during exercise in both groups, most markedly in the dihydralazine group. After exercise plasma renin activity decreased to pre‐exercise level in the control group but continued to increase in the dihydralazine group in spite of the increased renal blood flow. The findings indicate more marked sympathetic activity in the dihydralazine group and it is suggested that the sympathetic nervous system may have a direct influence on renin release irrespective of its renal hemodynamic action.
Effect of Ganglionic Blocking on Plasma Renin Activity in Exercising and Pain‐Stressed Rats
Authors: Božović Ljubomir , Castenfors Jan 
Published: December 2008

AbstractThe effect of ganglionic blocking on piasma renin activity and plasma sodium concentration during exercise and pain stress were studied in rats. 20 female albino rats were exercised by swimming and 16 received intramuscular injections of 1 ml 10% NaCl. Half of the animals in each group were pretreated with a ganglionic blocking drug (Ansolysen®). In both groups there was a significantly lower plasma renin activity in the ganglion‐blocked animals compared with their untreated controls, which indicates the importance of the sympathetic system for renin release. The findings suggest that changes in plasma sodium concentration are of minor importance compared with sympathetic activity.
The Effects of Varying the Extracellular Potassium Concentration on the Secretory Rate and on Resting and Secretory Potentials in the Perfused Cat Submandibular Gland
Authors: Petersen Ole Holger , Poulsen Jørgen Hedemark 
Published: December 2008

AbstractLundberg presented the hypothesis that the secretory potentials in salivary glands were due to an active transport of chloride ions. This transport should be responsible for the formation of the saliva. Recently a different hypothesis has been proposed by Imai, who postulated that the secretory potentials were caused by an increased permeability of the cell membranes to potassium ions. The present investigation was undertaken to test Imai's hypothesis. It was found that the secretory potentials and the secretory rate depended in very much the same way on the extracellular potassium concentration. This gives further support to Lundberg's hypothesis.