bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE RELATIONSHIP OF THE THYROID GLAND TO MUSCULAR WORK PERFORMED BY THE ALBINO RAT
Authors: Cox L. W. 
Published: December 2014

1. Muscular work performed by the sciatic nerve‐gastrocnemius muscle preparation in the anæthetised rat is recorded when normal, high, and low thyroid hormone levels are present.2. Hypothyroid animals performed less work than normal animals.3. Hyperthyroid animals performed less work than normal animals.4. Thyroidectomized animals, with iodine added to the diet, performed work at a rate not significantly different from normal animals.5. All animals on which thyroidectomy had been performed, showed a phase of sustained contraction, lasting ¼ to 2 hours, at the commencement of the experiment. This phase was not due to hypocalcæmia, and possibly was not due to defective neuro‐muscular transmission.6. No animal, normal or abnormal in thyroid metabolism under the conditions stated, showed muscular fatigue during the twenty hours of the experiment.
Spatial and temporal summation in impaired regions of the visual field
Authors: Wilson M. E. 
Published: December 2014

1. Spatial and temporal summation have been measured in perimetrically impaired regions of the visual field. Two classes of impairment have been studied: that resulting from lesions in the pre‐geniculate visual pathways, and that resulting from post‐geniculate lesions (optic radiation and/or striate cortex).2. Control measurements were made in the perimetrically normal visual fields of subjects without visual pathway damage.3. Spatial summation was found altered in all impaired visual fields: the greater the threshold elevation produced by the lesion, the more nearly complete was spatial summation.4. The above relation between threshold and spatial summation has also been given numerical form. This has been shown to be very nearly identical to the threshold—spatial summation relation which is seen as stimuli are increasingly peripherally presented in normal visual fields.5. It has been shown that the alterations of spatial summation brought about by a lesion are found only in those parts of the visual field which are perimetrically impaired: spatial summation is always normal in perimetrically normal regions of a visual field, even if other parts of the same field show impairment.6. Temporal summation has been found altered in visual fields impaired by post‐geniculate lesions: the greater the threshold elevation produced by the lesion, the more nearly complete was temporal summation. These changes in temporal summation were found only in perimetrically impaired regions of the field.7. Temporal summation was normal in visual fields impaired by pregeniculate lesions.
The response of single units in the caudate nucleus to peripheral stimulation
Authors: Sedgwick E. M. , Williams T. D. 
Published: December 2014

1. Extra‐ and intracellular recordings have been made of single units in the caudate nucleus of the cat, anaesthetized with alpha chloralose.2. Pentobarbitone was shown to depress the spontaneous activity and responses of units in the caudate nucleus.3. Spontaneous activity of units usually took the form of single spikes or bursts of up to four spikes occurring every 100‐300 msec.4. The response to electrical stimulation of limb nerves was a burst of 1‐4 spikes after a latency of about 30 msec. Convergence from all four limbs on to single units was observed. It is shown that muscle afferents do not cause these responses.5. Post stimulus histograms of spontaneously active units show, following stimulation of the limb nerves, recurring cycles of excitation and inhibition at a rate of 3‐4 c/s and lasting for several seconds. It is suggested that each stimulus synchronizes the normally rhythmic spontaneous activity.6. Similar responses have been obtained following stimulation by clicks and flashes of light.7. Stimulation of the ipsilateral cerebral cortex gave excitatory and inhibitory responses similar to those described above.8. Possible mechanisms for these responses and their significance are discussed.
Inhibition of gastrointestinal movement by sympathetic nerve stimulation: the site of action
Authors: Gershon M. D. 
Published: December 2014

1. The mechanism of sympathetic nervous inhibition of gastrointestinal movement was investigated in order to determine whether the primary action of sympathetic nerve stimulation was on ganglia or on the smooth muscle itself.2. The effect of sympathetic nerve stimulation did not resemble the effect of ganglionic blockade or that of removing all nervous tone with tetrodotoxin.3. The same frequency of sympathetic nerve stimulation to the rabbit jejunum which inhibited the myogenic spontaneous activity blocked excitatory responses to transmural post‐ganglionic cholinergic nerve stimulation and antagonized contractions in response to drugs acting directly on the smooth muscle.4. Acetylcholine output was measured as an indicator of post‐ganglionic nervous activity. In contrast to hexamethonium, stimulation of sympathetic nerves at frequencies of stimulation sufficient to relax the muscle did not reduce the output of acetylcholine.5. Vagus nerves and sympathetic nerves to the guinea‐pig stomach were stimulated individually and simultaneously in the presence of hyoscine. The relaxant responses to stimulation of the two nerves summated when they were stimulated simultaneously, indicating that the transganglionic vagal pathway was not blocked.6. It is concluded that the effect of sympathetic nerve stimulation is due to the direct action of the released noradrenaline on the smooth muscle.
Resting and spike potentials of skeletal muscle fibres of salt water elasmobranch and teleost fish
Authors: Hagiwara Susumu , Takahashi Kunitaro 
Published: December 2014

1. Membrane properties of the muscle fibre were studied in twitch motor system of sea‐water elasmobranch (Taeniura lymma, Himantura uarnak and Pastinachus sephen) and teleost fish (Periophthalmodon barbarus, Tetradon immaculata, Hemiramphus welsby, Parexocoetus brachypterus and Conger labiatus).2. The resting potential of the elasmobranch fibre is mainly determined by the Cl− concentration difference between inside and outside the membrane whereas the K+ conductance is the determining factor in teleost fibres.3. The resting membrane of the elasmobranch fibre is permeable not only to Cl− ions but also several other anions (Br−, I−, NO3−, SCN−, ClO4−, ClO3−) of large limiting conductivities in the aqueous solution.4. The spike potential of the elasmobranch fibre always shows a significant overshoot in normal saline while no significant overshoot is generally found in teleost fibres.5. In both elasmobranchs and teleosts the spike is produced by the permeability increase of the membrane to Na+ ions and is effectively suppressed by tetrodotoxin at a concentration of 0·5‐1·0 × 10−7 g/ml. of the external solution with one exception, i.e. the Na+ spike of Tetradon fibre is not suppressed by the toxin even when the concentration is above 5 × 10−4 g/ml.
Active transport of ions by the gastric mucosa of the rabbit foetus
Authors: Kendall Anne , Wright G. H. 
Published: December 2014

1. The short‐circuit current and absolute fluxes of Na+ and Cl− across the gastric mucosa of the 28‐day rabbit foetus have been measured in vitro.2. Substitution of Na+ in the solution bathing the mucosal surface by choline ion or K+ resulted in a 70% decrease in short‐circuit current which was reversed when Na+ was restored to the mucosal solution. The portion of the short‐circuit current dependent on the presence of Na+ in the mucosal solution was found to be equivalent to the net flux of Na+ from mucosa to serosa.3. The net flux of Cl− from serosa to mucosa was compared with the short‐circuit current persisting when Na+ had been replaced in the mucosal solution. Averaged results from sixteen experiments indicated that the net flux of Cl− was equivalent to 166% of the Na+ independent short‐circuit current.4. The results indicated that the component of short‐circuit current associated with acid secretion was independent of the presence of Na+ in the mucosal solution.5. The small scale of the experiments and the secretion of mucus by the preparation did not permit successful simultaneous measurement of H+ secretion and short‐circuit current.6. Replacement of Cl− by SO42- or glucuronate in the solutions on both sides did not result in a reversal or decrease in magnitude of the Na+ independent short‐circuit current, even after allowing time for the tissue to become depleted of Cl−. It is suggested that a non‐specific active anion transport was occurring.
S‐potential and dark adaptation in fish
Authors: Naka K. I. , Rushton W. A. H. 
Published: December 2014

1. The change in d.c. level of the S‐space was investigated during dark adaptation to see if there is any correlation between the d.c. level and log sensitivity.2. Except for a few minutes after strong adaptation the d.c. level of the S‐space was found unchanged throughout dark adaptation.3. The maximal excursion of the potential (the ceiling) also remained unchanged during the light and dark adaptation.4. Changes in the sensitivity in dark adaptation were found formally equivalent simply to a change in the unit of light intensity.5. Thus adaptations to bleaching or to the equivalent background are entirely different in the effect on S‐potentials.
Evidence for the vesicle hypothesis
Authors: Hubbard J. I. , Kwanbunbumpen Suthiwan 
Published: December 2014

1. The relationship of synaptic vesicles to the synaptic cleft was examined with the electron microscope at neuromuscular junctions in the rat diaphragm before and after bathing the preparation in a physiological salt solution for 2 hr.2. A population of vesicles was defined which appeared to ‘touch’ the axoplasmic membrane. These vesicles were found to be aggregated adjacent to axoplasmic densities which lay opposite the mouths of post‐synaptic junctional folds.3. Soaking in the salt solution and modifications of this solution increased the proportion of folds opposed by presynaptic densities with associated vesicles.4. Soaking in solutions with 20 m
M‐KCl depleted both the specific vesicle population and the whole population of terminal vesicles. The effect was shown in paired experiments to be a specific effect of the 20 m
M‐KCl, and it was prevented by a concomitant increase of the bathing MgCl2 concentration.5. Soaking in solutions with a raised osmotic pressure reduced the specific but not the general vesicle population.6. It is suggested that these observations support the vesicle hypothesis and that the specific vesicle population forms part of a feed‐back mechanism adjusting transmitter synthesis and mobilization to the rate of release of transmitter.
Release by tubocurarine of dopamine and homovanillic acid from the superfused caudate nucleus
Authors: Portig P. J. , Sharman D. F. , Vogt Marthe 
Published: December 2014

1. The release of dopamine and its metabolite homovanillic acid from the ‘superfused’ caudate nucleus was studied in the cat. Fluorimetric assay of the two compounds was carried out on 30 min samples of artificial cerebrospinal fluid perfused through the anterior horn of one lateral ventricle.2. When tubocurarine 0·5 or 1 × 10−4 g/ml. was added to the perfusion fluid, amounts of dopamine of the order of 0·1 ng/min, and very much larger quantities of homovanillic acid (up to 8 ng/min) appeared in the perfusing fluid.3. No release of dopamine was obtained under conditions when tubocurarine failed to produce any clinical signs or when gallamine was substituted for tubocurarine.
Factors modifying renal tubular bicarbonate reabsorption in the dog
Authors: Ullmann Elisabeth 
Published: December 2014

1. Acute experiments were carried out on anaesthetized dogs during metabolic alkalosis produced by
I.V. administration of NaHCO3. Partial constriction of one ureter led to a significant rise in the HCO3− threshold, beyond the simultaneous value for the other kidney. The magnitude of the increase was not correlated with the reduction of glomerular filtration.2. Stop‐flow analysis, following complete unilateral obstruction of urine flow, demonstrated proximal as well as distal tubular reabsorption of bicarbonate. At any given plasma PCO2 the detailed configuration of the concentration changes which developed depended on (a) the presence and concentration of mannitol, (b) the duration of urinary stasis, and (c) the plasma concentration of HCO3−.3. If a solution containing 15% (w/v) mannitol was infused
I.V., the HCO3− concentration in free flow urine was lower than in plasma, and it fell further during arrest of flow in the entire column of trapped fluid. If less mannitol was infused, or none at all, interruption of urine flow led to a striking increase of HCO3− concentration in the distal portion of the occluded column, and to a fall in the fluid arrested in the proximal segments.4. It was demonstrated that the HCO3− concentration attained after 2½, 6, or 15 min of urinary stasis at any point in the trapped fluid column was due to the combined effects of water reabsorption and HCO3− reabsorption which proceeded independently, and with a different time course.5. If mannitol was administered the lowest urinary HCO3− concentration in the series moved progressively to a more distal location with increasing duration of urinary stasis. When HCO3− concentration peaks were present in distal fluid they were conspicuous only after short interruptions of urine flow; during extended stop‐flow periods they became attenuated, or disappeared. If no mannitol was administered this did not occur.6. Provided the plasma level of HCO3− was sufficiently elevated, mannitol (15%, w/v) was administered, and the time available for reabsorption was lengthened by ureter obstruction, much larger concentration differences between plasma and trapped fluid developed than the largest that are ever found between the plasma and freely draining urine. The magnitude of the largest plasma—urine (P—U) concentration difference for HCO3− increased with intratubular ‘contact time’, and no limiting value was found.7. Potassium concentration in distal occluded fluid fell with prolonged duration of stasis. This was related to the slow and progressive diminution of distal HCO3− concentration. But if instead of bicarbonate a nonreabsorbable anion, such as phosphate, was the dominant distal anion, K+ concentration in distal fractions remained high and rose further with time.
Vasomotor responses in the hind limbs of foetal and new‐born lambs to asphyxia and aortic chemoreceptor stimulation
Authors: Dawes G. S. , Lewis B. V. , Milligan J. E. , Roach Margot R. , Talner N. S. 
Published: December 2014

1. Hind limb blood flow was measured in lambs of from 91 days gestation (delivered by Caesarean section) to 1 month after birth (term is about 147 days), under chloralose anaesthesia. Vascular resistance/100 g wet wt. increased progressively with age. There was reflex femoral vascular tone from the earliest age studied, as shown by vasodilatation on cutting the sciatic nerve.2. On asphyxia by cord occlusion reflex femoral vasoconstriction began earlier and was somewhat greater in older foetal lambs. At all ages, and after denervation of the hind limb, there was vasodilatation after local ischaemia, and a vasoconstriction of delayed onset during asphyxia attributed to release of noradrenaline into the circulation. The vasoconstrictor effect of noradrenaline in immature lambs was at least as great as at term or in the new‐born.3. Injections of minimal effective doses of cyanide were used to localize possible chemoreceptor sites in foetal lambs. Injection into the left atrium caused a rise of arterial pressure, femoral vasoconstriction and a complex change in heart rate (usually bradycardia) but rarely any respiratory movement. After atropine, cyanide caused a large tachycardia. All responses were much reduced or abolished by cervical vagotomy.4. Injection of the same doses of cyanide into a jugular vein, the right ventricle, pulmonary or common carotid arteries of foetal lambs caused negligible cardiovascular or respiratory effects, whereas injection into the carotids of new‐born lambs caused a profound hyperpnoea.5. It is concluded that the aortic chemoreceptors are active in the foetus, are supplied from the left heart, and that they probably represent the primary defence in blood gas homeostasis by their effects on the circulation.
Water and sodium absorption in the human intestine
Authors: Love A. H. G. , Mitchell T. G. , Phillips R. A. 
Published: December 2014

1. Studies are reported of total intestinal perfusion in man in which data relating to the absorptive capacity for water and sodium, flow rate transit time and intestinal volume have been obtained.2. A 'bolus' of radiosodium added to the steady‐state perfusion has allowed measurement of bidirectional fluxes of sodium ion across the mucosa to be determined.3. The values obtained agree closely with those that can be predicted from small segmental studies reported in the literature.4. Increasing absorption capacity with increasing flow rate does not seem to reflect a true increase in absorption per unit of intestine but rather a progression to more nearly continuous flow conditions.
Effect on temperature of 5‐hydroxytryptamine injected into the cerebral ventricles of cats
Authors: Banerjee U. , Burks T. F. , Feldberg W. 
Published: December 2014

1. In unanaesthetized cats the effect on rectal temperature was examined of 5‐HT injected through a Collison cannula chronically implanted into the left lateral ventricle. The response depended on the amount of 5‐HT injected and on the solvent employed.2. An intraventricular injection of 200 μg 5‐HT creatinine sulphate dissolved in 0·9% NaCl solution resulted in a long‐lasting rise often interrupted initially by a transient fall in temperature.3. This fall became more prominent with larger doses of 5‐HT; even more when the 5‐HT was dissolved in distilled water, and then the hyperthermic effect was attenuated.4. It is concluded that intraventricular 5‐HT raises rectal temperature in cats when the amount is not too large, and that a hypothermic effect when it occurs results from paralysis of cells in the anterior hypothalamus which are excited by small doses. This would be similar to the actions of acetylcholine in the perfused superior cervical ganglion of the cat, where small doses excite but large doses paralyse the ganglion cells.5. An intraventricular injection of distilled water produced a steady rise in temperature which is attributed to release of 5‐HT.
Adaptation in the goldfish retina
Authors: Easter S. S. 
Published: December 2014

1. Isolated photopic goldfish retinas were stimulated and adapted by red light, and the spike activity of single ganglion cells was monitored by micro‐electrodes.2. A unit's threshold to illumination of one part of its receptive field was often raised by adapting spots which fell elsewhere. An adapting spot of fixed area and intensity always desensitized the unit most when focused at the test position.3. When adapting and testing spots were given concentrically, the large adapting spots raised the test threshold more than the smaller adapting spots, even though all completely covered the test spot. Quantitative considerations rule out scattered light as an explanation; there must be a neural mechanism, an adaptation pool, which sets the sensitivity on the basis of quanta received over a field hundreds of microns in diameter.4. The desensitization is a non‐linear function of area and intensity.5. The adaptation pool's field is not coincident with the ganglion cell's receptive field.
Factors affecting the conductivity of pathways in the cerebral cortex
Authors: Bliss T. V. P. , Burns B. Delisle , Uttley A. M. 
Published: December 2014

1. We have investigated the conductivity of neural pathways in slabs of unanaesthetized, isolated, cerebral cortex, cut from the isolated forebrains of twenty‐five cats.2. Neurones within the isolated area were indirectly excited, either by a small electrode thrust into the subcortical white matter, or by remote stimulation of the pial surface. Sometimes a small electrode was employed for intracortical stimulation.3. The response of single neurones to these stimuli was recorded with extracellular micropipettes. Submaximal stimuli produced a stochastic response which was measured from the post‐stimulus histogram (PSH) and provided an estimate of the probability of discharge at various times after the stimulus.4. The PSH often displayed several discrete humps of different latencies, indicating several pathways between stimulated and recording point. Conductivity measurements were usually restricted to the pathway of shortest latency.5. The conductivity of a pathway was defined as C = xy/x, averaged over 1 or 2 min, wherex = frequency of afferent test volleys,xy = frequency of response: i.e. of those action potentials contained within a well‐defined hump of the PSH,(y = frequency of all discharges of the recorded neurone).6. The progress of conductivity was tested with some constant form of cortical stimulation, repeated at regular intervals of 1‐5 sec. Reliable results were obtained for twenty‐six pathways subjected to thirty‐eight experiments.7. Temporary alteration of x, y or xy (conditioning with Δx, Δy or Δxy), for a period of 6‐25 min, often caused a subsequent change in the conductivity (ΔC) of a pathway which sometimes attenuated with a time constant of about 10 min, but which could persist without detectable attenuation for 20‐30 min.8. Conditioning periods less than 6 min rarely produced changes in conductivity; alterations of conductivity were more likely to be caused by conditioning periods longer than 17 min, than by periods of 6‐16 min.9. Changes in conductivity were usually correlatednegatively with temporary changes in xy,negatively with temporary changes in x,positively with temporary changes in y.10. Nineteen of twenty‐six pathways tested showed properties consistent with the formula [Formula: see text], whereG1 lies between ‐1·0 and ‐0·16, with mean value ‐0·50,G2 lies between 0 and 0·42, with mean value +0·12,G3 lies between ‐0·61 and 0 with mean value ‐0·38,K is a coefficient which is usually different for each experiment.Four out of twenty‐six pathways so tested provided results which did not fit this formula; three out of twenty‐six pathways did not give adequate information.
Influence of intragastric pH on electrolyte secretion by the guinea‐pig stomach
Authors: James R. M. V. 
Published: December 2014

1. A technique is described for the continuous assessment of acid secretion by the guinea‐pig gastric mucosa at selected levels of intragastric pH.2. The rate of hydrogen ion secretion increases linearly with pH over the intragastric range of pH 4·4 to 9·4. Sodium and potassium secretions are not clearly related to pH. Outputs of both chloride and bicarbonate rise as pH is increased.3. The carbonic anhydrase inhibitor acetazolamide reversibly reduces rapid rates of acid secretion as occur when gastric contents are maintained at pH 10.4. Alkali stimulated acid output is not inhibited by atropine (2 mg/kg) and probably results directly from increased carbonic anhydrase activity as the in vitro activity of the enzyme may be correlated with the rate of acid secretion over a wide range of pH.