bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct measurements of membrane potential and membrane resistance of human red cells
Authors: Lassen U. V. , Sten-Knudsen O. 
Published: December 2014

1. In order to evaluate the membrane potentials calculated from the distribution of chloride ions in human red cells and plasma, it is desirable to have a direct measurement of the transmembrane potential of these cells.2. A method has been devised for introducing a capillary micro‐electrode into human red cells. The method allows simultaneous measurements of potential and membrane resistance with only one micro‐electrode located in the cell.3. Upon impalement of single cells in plasma, a scatter of membrane potentials and of resistance values was obtained. The potential drop never exceeded ‐14 mV and the maximum resistances were about 7 Ω. cm2. Positive potentials were obtained on impalement of red cell aggregates.4. Arguments are given to support the view that it is in these cells which suffer least damage from the impalement that maximum values of membrane potentials and resistances are observed. The errors caused by the change in the liquid junction during the impalement have been estimated.5. As judged from this study, it seems permissible under normal conditions to calculate the membrane potential of the red cell from the chloride concentrations in plasma and in intracellular water.
Activity of cells in the lateral vestibular nucleus as a function of head position
Authors: Fujita Y. , Rosenberg Jay , Segundo J. P. 
Published: December 2014

1. The spike activity of cells in the lateral vestibular nucleus was recorded in cats anaesthetized with pentobarbital sodium. Natural labyrinthine stimulation was applied by fixing the animal at different positions reached through roations about a longitudinal or transverse axis.2. The majority of cells responded to rotations only about the longitudinal axis. Two types of response were found. The first was characterized by a transient change in activity which occurred only during the movement. The second type had an initial transient component and a subsequent steady component that persisted as long as the head remained fixed.3. The interspike interval means, standard deviations, histograms and autocorrelograms of the steady response components of cells sensitive to lateral tilt were calculated. In every cell the relation between the head position with respect to gravity and the mean interspike interval of the steady discharge showed two main features. (a) ‘Directional sensitivity’: the mean interval increased following rotation in one sense, and decreased following rotation in the other. In twenty‐two out of thirty‐three cells, the mean increased when the recording side was raised. The remaining cells showed the opposite relation. (b) ‘Multivaluedness’: each particular position is associated with several different values of mean interval and these values had a relatively wide scatter. The curve that resulted from joining points in the order in which they occurred during the experiment was either closed, open, or combined closed and open portions.4. The standard deviations, histograms and autocorrelograms also showed directional sensitivity and multivaluedness with respect to position. Several types of interspike interval histograms and autocorrelograms characterized lateral vestibular activity. The forms of the histogram and the autocorrelogram of the discharge from each cell usually remained unchanged during stimulation.5. The extensive spread of the multivaluedness implies that observation of the mean interspike interval of a specified cell can lead only to a probabilistic statement about head position. Joint observations of mean, standard deviation and histogram, or joint observation of several cells or knowledge of the previous history of the movement may lead to a more accurate determination of position.6. Experiments in animals with only one labyrinth showed that each labyrinth can both accelerate and decelerate activity in both vestibular nuclei.
Frequencygrams of spindle primary endings elicited by stimulation of static and dynamic fusimotor fibres
Authors: Bessou P. , Laporte Y. , Pagès B. 
Published: December 2014

1. Frequencygrams of cat spindle primary endings, obtained by the method described by Bessou, Laporte & Pagès (1968), were elicited by the stimulation of single static and dynamic fusimotor fibres.2. Stimulation of static fibres by single stimuli may elicit: (i) no response, (ii) responses of small amplitude, (iii) responses of large amplitude with a pause after the rising phase.3. Stimulation of static fibres by repetitive stimuli gives frequencygrams resembling records of tetanic contraction of skeletal muscle. At a frequency of stimulation of 180‐200/sec periodic oscillations are perceptible on the plateau of the frequencygram.4. Stimulation of dynamic fibres by single stimuli may elicit: (i) no response, (ii) responses smaller and longer than the responses given by static fibres.5. When the muscle is stretched the amplitude of the responses elicited by dynamic fibres decreases whereas the amplitude of the responses given by static fibres increases.6. Frequencygrams obtained by repetitive stimulation of dynamic fibres show periodic oscillations only at low rates of stimulation. At rates of stimulation higher than the minimal rate giving frequencygrams with a smooth contour, the amplitude of the frequencygram increases.
Some properties of the smooth muscle of rabbit portal vein
Authors: Holman Mollie E. , Kasby C. B. , Suthers M. B. , Wilson Jane A. F. 
Published: December 2014

1. The morphology of the smooth muscle of the rabbit portal vein and its innervation were studied with fluorescence and electron microscopy. Two layers of smooth muscle were observed in the tunica media: an inner layer of circularly arranged muscle cells and an outer layer consisting of bundles of smooth muscle cells arranged in a near longitudinal direction. The membranes of neighbouring smooth muscle cells were occasionally fused to form ‘tight junctions’.2. Bundles of non‐myelinated nerve fibres were observed in the adventitia, and between bundles and layers of smooth muscle cells in the media. Studies on longitudinal sections with fluorescence microscopy revealed a network of varicose noradrenergic axons.3. Electrical and mechanical activity was recorded from longitudinal strips of smooth muscle from the media of the vein with a sucrose‐gap apparatus.4. The preparation was spontaneously active under minimal resting tension (less than 150 mg) and at temperatures above 28° C. Slow depolarizations led to a burst of spikes (multi‐spike complexes), which corresponded to rhythmic contractions. In 10% of preparations, the interval between multi‐spike complexes showed a slower depolarization, suggesting the record was from a pace‐maker region.5. The frequency of spontaneous activity (3‐27 beats/min) was very sensitive to changes in temperature and tension.6. Noradrenaline in low doses (0·01 μg) caused an increase in frequency of the multi‐spike complexes. Higher doses (0·1‐0·3 μg) initiated continuous high‐frequency spiking, while very high doses (0·6‐2·0 μg) caused maintained depolarization.7. Responses to repetitive electrical stimulation of the vein were qualitatively similar to those in response to exogenous noradrenaline. The relation between the mechanical response and the various parameters of stimulation was consistent with the stimulation of sympathetic nerve fibres in the wall of the vein.8. The actions of isoprenaline, phentolamine and propranolol indicated the presence of α ‘excitatory’ and β ‘inhibitory’ adrenotrophic receptors on the smooth muscle.
Water and electrolyte secretion by the perfused pancreas of the cat
Authors: Case R. M. , Harper A. A. , Scratcherd T. 
Published: December 2014

1. A technique is described for perfusing the isolated cat pancreas with saline solutions.2. Single doses of secretin, although present in the perfusate for only a short time, caused a prolonged flow of pancreatic juice.3. In response to continuous secretin infusion, the preparation secreted for up to 6 hr a juice which was similar to that obtained in vivo, with the exception that the bicarbonate concentration decreased and the chloride concentration increased with time, even when the rate of secretion remained constant.4. The osmolalities of perfusate and secretion were identical over a range of 450 m‐osmoles/kg, but the electrolyte concentration of the secretion was always slightly higher than that of the perfusate. Variations from perfusate isosmolality produced inverse changes in the secretion rate, over the range from 600 m‐osmoles/kg, at which secretion ceased, to 150 m‐osmoles/kg, at which the rate was highest. At perfusate osmolalities below 150 m‐osmoles/kg secretion rapidly declined.5. Reduction in perfusate sodium chloride concentration, isosmolality being maintained with sucrose, caused a fall in secretion rate, but the sodium concentration of the juice remained constant until perfusate sodium concentration was reduced to about 70 m‐equiv/l. Below this level it declined and sucrose was detected in the juice in quantities almost sufficient to account for the equiosmolality of juice and perfusate.6. Two hypotheses about the mechanism of water and electrolyte secretion by the pancreas are presented.
The dependence on external cations of the oxygen consumption of mammalian non‐myelinated fibres at rest and during activity
Authors: Rang H. P. , Ritchie J. M. 
Published: December 2014

1. A study has been made of the effect of potassium and other cations on the oxygen consumption of rabbit desheathed vagus nerves at rest and during activity.2. In normal Locke solution (containing 5·6 m
M‐K) the resting oxygen consumption, Qr, was 0·0903 μmole/g wet wt. min. The extra oxygen consumed as a result of stimulation, Qs, at 3 stimuli/sec was about 600 p‐mole/g.impulse; at 30 stimuli/sec it was less, being 240 p‐mole/g.impulse.3. Only a fraction of Qr (18% at 5·6 m
M‐K) was sensitive to ouabain (1 m
M). The ouabain‐sensitive component, however, increased as the external potassium concentration was increased, in the range 0‐100 m
M. Qs was virtually abolished by ouabain.4. Reduction of the external potassium concentration from 5·6 m
M to zero reduced Qr (by 10%) and increased Qs, but the changes were scarcely significant statistically.5. The conclusions were drawn: that Qs reflected the pumping of cations to restore the ionic imbalance following activity, particularly reflecting the extrusion of sodium ions from the fibre; that this pumping was normally absolutely dependent on the presence of potassium externally and that no pumping could occur in its absence; and that Qs was not reduced to zero in ostensibly potassium‐free solutions because enough potassium was released into the periaxonal space during activity to maintain pumping.6. Thallium, rubidium, caesium and lithium could replace potassium and allowed pumping to occur.
Onset of and recovery from diving bradycardia in ducks
Authors: Butler P. J. , Jones D. R. 
Published: December 2014

1. No evidence was found of a ‘postural reflex’ in ducks. Neither the position of the head nor the water temperature affected the cardiac response to diving.2. In ducks with access to air through a tracheal cannula, submersion did not invariably cause apnoea until the water level reached the glottis. Heart rate was closely related to respiratory frequency, and bradycardia did not occur during submersion unless there was a reduction in respiratory frequency or a cessation of ventilation altogether.3. When apnoea and bradycardia did occur during submersion, the first inspiration upon surfacing was 2‐3 times larger than normal and was accompanied by an instantaneous rise in heart rate.4. Atropinization or cold block of the vagus abolished diving bradycardia. Only one vagal trunk was involved in cardiac chronotropic control at any one time. This vagal trunk also appeared to be more important in control of respiratory frequency.5. β‐adrenergic receptor blockade did not affect either diving bradycardia or post‐dive tachycardia.6. The results show that the cardiac chronotropic response both during and after submergence is controlled solely by changes in parasympathetic vagal activity.
Rhythmical and non‐rhythmical spontaneous activity recorded from the central cut end of the sinus nerve
Authors: Biscoe T. J. , Sampson S. R. 
Published: December 2014

1. Two types of spontaneous nervous activities have been recorded from the central cut end of the carotid sinus nerve of the cat.2. One type was composed of nerve potentials that exhibited a respiratory or cardiac rhythm, whose rate of firing was depressed by the pressor response to adrenaline, and that were found to arise from post‐ganglionic fibres of the superior cervical ganglion.3. The other type of activity consisted of non‐rhythmical nerve potentials whose rate of discharge increased 10‐30 sec after the injection of adrenaline. The activity of these fibres also increased when the arterial oxygen tension was lowered or when the arterial carbon dioxide tension was raised.4. It is conceivable that either of these two groups of fibres, rather than the chemoreceptor afferent fibres, could provide the source of the microvesicle‐containing nerve endings on the type 1 cells of the carotid body.5. A nerve was also described coursing from the sinus nerve to the hypoglossal nerve; the activity in it was sympathetic in origin.
The sensations produced by electrical stimulation of the visual cortex
Authors: Brindley G. S. , Lewin W. S. 
Published: December 2014

1. An array of radio receivers, connected to electrodes in contact with the occipital pole of the right cerebral hemisphere, has been implanted into a 52‐year‐old blind patient. By giving appropriate radio signals, the patient can be caused to experience sensations of light (‘phosphenes’) in the left half of the visual field.2. The sensation caused by stimulation through a single electrode is commonly a single very small spot of white light at a constant position in the visual field; but for some electrodes it is two or several such spots, or a small cloud.3. For weak stimuli the map of the visual field on the cortex agrees roughly with the classical maps of Holmes and others derived from war wounds. With stronger stimuli, additional phosphenes appear; these follow a map that is roughly the classical map inverted about the horizontal meridian.4. The phosphenes produced by stimulation through electrodes 2·4 mm apart can be easily distinguished. By stimulation through several electrodes simultaneously, the patient can be caused to see predictable simple patterns.5. The effects of the duration and frequency of stimulating pulses on the threshold have been explored.6. For cortical phosphenes there is no sharp flicker fusion frequency, and probably no flicker fusion frequency at all.7. During voluntary eye movements, the phosphenes move with the eyes. During vestibular reflex eye movements they remain fixed in space.8. Phosphenes ordinarily cease immediately when stimulation ceases, but after strong stimulation they sometimes persist for up to 2 min.9. Our findings strongly suggest that it will be possible, by improving our prototype, to make a useful prosthesis.
Firing patterns of gastrocnemius motor units in the decerebrate cat
Authors: Burke R. E. 
Published: December 2014

1. The patterns of medial gastrocnemius (MG) motor unit firing in response to MG muscle stretch have been studied in decerebrate cats, using intracellular recording techniques. In most of the units, the motoneurone axonal conduction velocity and cell input resistance were measured, and the maximum amplitude and wave form of the group Ia composite EPSP evoked by MG nerve stimulation were determined. The mechanical properties of the muscle unit portion of each motor unit were also studied.2. Motor unit firing patterns were classified into two groups, ‘tonic’ and ‘phasic’. With few exceptions, tonic motor units showed sustained firing throughout MG stretches of varying duration, while most phasic units did not fire at all to the same stimulus. Tetanization of the afferents did not convert any of the previously phasic units to tonic firing.3. MG motor units in this study were divided into three groups on the basis of the muscle unit twitch properties. Units with short twitch time to peak values (< 35 msec) were subdivided into two groups according to twitch tension output: (a) type F, with twitch tension > 1·5 g, and (b) type F*, with twitch tension < 1·5 g. Units with slow twitch time to peak (> 35 msec) were classified as type S.4. The presence or absence of tonic firing during sustained MG stretch was found to be significantly related to the following factors: (a) the motor unit twitch type, in that tonic firing was observed in 100% of type S, 70% of type F*, and only 10% of type F units; (b) the apparent motoneurone size, in that tonic units tended to have higher cell input resistance values and slower axonal conduction velocities than phasic units; and (c) the density and spatial organization of the group Ia synaptic input, in that the MG monosynaptic EPSPs found in tonic motor units tended to be both larger in amplitude and longer in duration than those found in phasic units.5. The intrinsic properties of MG motor units, the characteristics of the group Ia synaptic input to the motoneurones and the unit firing patterns elicited by MG muscle stretch appear to be mutually interrelated, forming a pattern of motor units within the MG pool which is analogous to the pattern thought to characterize the motor units belonging to ‘slow’ and ‘fast’ muscles. In most respects this pattern of MG motor units appears to be a continuum without clearly separable subgroups.
The contribution of the arterial chemoreceptors to the stimulation of respiration by adrenaline and noradrenaline in the cat
Authors: Joels N. , White H. 
Published: December 2014

1. Intravenous infusions of adrenaline and noradrenaline in doses averaging 0·8 μg/kg.min increased the respiratory minute volume of anaesthetized cats breathing room air. The mean increase in respiratory minute volume was 14% during adrenaline infusion and 8% during noradrenaline infusion.2. In a small group of decerebrate cats infusions of adrenaline and noradrenaline increased ventilation by 19 and 27% respectively.3. Intravenous catecholamine infusions also increased the respiratory responses of anaesthetized animals to the inhalation of 5% or 10% O2 in N2 and to the inhalation of 5% CO2 in air.4. Adrenaline and noradrenaline infusions had no significant effect on the ventilation of animals breathing 100% O2, nor did they significantly alter the respiratory response to the inhalation of 5% CO2 in O2.5. After section of the carotid sinus and aortic nerves, a blood‐pressure compensator being used to minimize changes in arterial pressure, catecholamines had no effect on the respiration of cats breathing air.6. An increase in carotid body chemoreceptor discharge accompanied the increase in ventilation during catecholamine infusion.7. Intravenous catecholamine infusions still produced an increase in ventilation and carotid body chemoreceptor discharge after both aortic nerves and both cervical sympathetic nerves had been cut.8. Intra‐arterial infusions into one carotid artery of 0·2 μg/kg.min of adrenaline or 0·1 μg/kg.min of noradrenaline led to mean increases in respiratory minute volume of 9·9 and 11·5% respectively. No increase occurred after section of the corresponding carotid sinus nerve. Such infusions also evoked an increase in carotid body chemoreceptor discharge.9. It is concluded that the hyperpnoea produced by adrenaline and noradrenaline infusions in the cat is predominantly reflex in origin and is mediated by the arterial chemoreceptors.10. The increase in ventilation produced by adrenaline appears to have a component additional to its effect upon the chemoreceptors though the nature of this action has not been identified.
The response to stretch of muscle spindle afferents of baboon's tibialis anticus and the effect of fusimotor stimulation
Authors: Koeze T. H. 
Published: December 2014

1. Systematic studies of the response of baboon's tibialis anticus muscle spindles to stretch were undertaken. Most of the spindle afferents studied had conduction velocities between 72 and 78 m/sec with a range from 39 to 93 m/sec. There was no clear bimodality in the histogram of the conduction velocity. Measurements were made of the axon diameters of the nerve to tibialis anticus. The largest number of the larger axons had diameters from 11 to 13 μ. The largest axon diameter measured 17 μ and there were very few of these.2. The dynamic index for any given afferent tended to be greater for the more rapidly conducting afferents and lower for the more slowly conducting afferents. However, a statistically significant regression line of this relationship could only be drawn for a stretch velocity of 64 mm/sec.3. The spindle afferent response to stretch was studied from different muscle lengths. It was found that the velocity sensitive portion of the response to phasic stretch decreased when the stretch extended up to or beyond the maximum physiological length of the muscle.4. Dynamic and static fusimotor fibres were isolated. The response of the spindle afferent to stretch, while the dynamic fusimotor fibre was being stimulated, was the same as that reported for the cat by P. B. C. Matthews (1962). During static fusimotor stimulation the response of the spindle afferent to stretch was usually like that reported for the cat. In a single case, however, static fusimotor stimulation resulted in a lowering of the peak frequency of the response of the spindle afferent to the phasic portion of stretch.
Slow inactivation of currents in cardiac Purkinje fibres
Authors: Reuter H. 
Published: December 2014

1. When membrane currents, associated with repolarization to the holding potential, were measured in cardiac Purkinje fibres after depolarizing voltage clamp steps to the plateau level of the action potential (‐20 to ‐10 mV), tails of inward current were observed which turned into outward current. Amplitude and duration of the tails of inward current increased when the preceding depolarization was progressively shortened. This current could only be recorded in Na‐containing solution which strongly supports the view that the inactivation of sodium conductance (gNa) has a slow and incomplete component.2. Initial outward current (most probably chloride current (ICl)) during strong depolarization (beyond ‐20 mV) could be inactivated either by increasing the frequency of depolarizations or by applying a conditioning depolarizing prepulse.3. In Na‐free solution a small, slowly decreasing inward current was recorded. This is most probably carried by calcium ions and is at least partly responsible for the negative conductance of the current—voltage relation in the voltage range ‐60 to ‐30 mV.4. If a strong conditioning depolarization (V1) to the inside positive potential range preceded repolarizing clamp steps to different membrane potentials (V2) inward current (probably calcium current (ICa) could be activated in Na‐free and Na‐containing solutions. This current depended on the duration of V1 as well as on the potential level of V2. After the maximum inward current, increasing outward current occurred when the duration of V1 was increased. This current could be explained either by an inactivation of calcium conductance (gCa) with time or by a very slow activation of an additional outward current.5. The main conclusions from these experiments are that (i) slow and incomplete inactivation of gNa are important features for the plateau of the action potential and (ii) calcium ions carry additional charge during this phase of the action potential. Chloride conductance (gCl) should be largely inactivated at a heart rate of 90/min.