bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fixed charge in the cell membrane
Authors: Elul R. 
Published: December 2014

1. Focal electric field was generated by passing a current of 5 × 10−7 to 1 × 10−5 A from a micropipette into the culture medium. Movement of cells at a distance of 5‐50 μ from the electrode tip was observed. In case of cells embedded in the culture only local deformation of the membrane was observed.2. The cell species explored included neurones, glia, muscle fibres, connective cells, malignant cells and erythrocytes. All cells responded in a similar manner to the electric field, and the current required was in the same range.3. Cells were attracted to a positive micropipette and repelled from a negative one: the only exception was observed in certain malignant cells which moved in the opposite direction.4. Movement and membrane deformation could be obtained with electrodes filled with various concentrated and isotonic solutions. The composition of the culture medium also had no qualitative influence on these effects.5. Metabolic poisons or rupture of the cell membrane had no effect on the movement. Isolated membrane fragments showed movement similar to that of intact cells.6. The possibility of artifacts due to proximity of the focal electrode is considered. It is shown that electro‐osmosis cannot account for the present observations. Some other artifacts are also excluded.7. It is proposed that the most satisfactory way to account for the present observations is by a membrane carrying negative fixed charge of the order of 2·5 × 103 e.s.u./cm2. Some physiological consequences of presence of negative charge in the membrane are briefly discussed.
Action of some foreign cations and anions on the chloride permeability of frog muscle
Authors: Hutter O. F. , Warner Anne E. 
Published: December 2014

1. Evidence for the existence in skeletal muscle of a specific cation binding system capable of lowering the chloride permeability was obtained by testing the effect of several metal ion species upon the efflux of 36Cl from frog muscles equilibrated in high‐KCl solution.2. Cu2+, Zn2+ and UO22+ ions, when present in concentrations of approximately 10−4
M in inactive wash solution at pH 7·4 slowed the efflux of 36Cl to half its original value. At pH 5·0, when the chloride permeability was already low as a consequence of hydrogen ion binding, these metal ions had little further effect.3. Presence of Ni2+, Co2+, Pb2+, Ce3+ and La3+ in 10−4
M or higher concentrations had no detectable influence on the 36Cl efflux. Wide variations in Ca2+ concentration were similarly ineffective.4. The influence of more adsorbable anions on the chloride permeability was examined at different pH values. Extracellular iodide greatly slowed the rapid efflux of 36Cl into alkaline solution. In acid solutions, when the chloride permeability was already low, the effect of iodide was less pronounced, but still demonstrable. The chloride permeability was consequently increased to a lesser extent by a rise in pH in the presence of iodide.5. The efflux of iodide and bromide was measured at different pH values under conditions of self exchange. In alkaline solution the permeabilities to iodide and bromide were considerably lower than that to chloride. In acid solution the membrane differentiated less between anion species of different adsorbability.
Spike propagation in the smooth muscle of the guinea‐pig taenia coli
Authors: Tomita T. 
Published: December 2014

1. Spike activity was produced by external field stimulation of the guinea‐pig taenia coli. Spikes were evoked by depolarization of the muscle membrane. Though the activity was usually also observed during hyperpolarization, this was shown to be conducted activity from the depolarized region of the tissue. Spike conduction was blocked when hyperpolarization exceeded 10 mV.2. The shape of the conducted spike was influenced by membrane polarization. Sometimes a notch appeared on the spike and sometimes the spike was split into two by hyperpolarization. This is probably due to the fact that functional bundles form a network and that the branches between bundles are more susceptible to the membrane polarization.3. There was a critical spike amplitude for normal propagation. Therefore, different spike amplitudes were observed near the stimulating electrode, but only spikes of nearly full size amplitude were recorded far from the stimulating electrode, i.e. at a distance of more than 5 mm.4. When repetitive stimulation was applied, the spike amplitude decreased with increasing frequency of stimulation. No steady level was reached, however, but the spike amplitude fluctuated at about 0·3 c/s.
The field potential profile during activation of the avian optic tectum
Authors: Holden A. L. 
Published: December 2014

1. The field potential profile resulting from electrical stimulation of the optic nerve‐head was recorded with micro‐electrodes inserted radially into the pigeon optic tectum.2. The first response, in the superficial tectum, was a graded negative wave, the N‐wave. Its latency was 2·3 msec,
S.D. 0·22 msec. The wave form underwent an abrupt polarity reversal in the R‐zone, to yield a graded positive wave, the P‐wave, in deeper laminae. The P‐wave had a latency of 2·0 msec,
S.D. 0·16 msec.3. Both N‐wave and P‐wave showed a graded increase in amplitude as stimulating current was increased. On any given track this increase occurred over a similar range of stimulating current.4. In many tracks the rise‐time and duration of the N‐wave were independent of amplitude.5. The rise‐time of the P‐wave was longer, and its duration was shorter, than the rise‐time and duration of the N‐wave. This effect was shown to be due to two successive sinks occurring superficially to the P‐zone.6. Depth profiles also showed these two sinks, separately located in the N‐zone and R‐zone.7. To paired stimuli the N‐wave showed refractoriness at intervals of 2‐4·5 msec, facilitation at intervals up to 25 msec, and subsequent depression. It showed low‐frequency depression at 10 and 20/sec.8. The R‐zone was localized by a lesion technique to sub‐layers d to g of the stratum griseum et fibrosum superficiale. Thus the tissue negativity was closely co‐extensive with the anatomical distribution of optic nerve terminals.9. It is suggested that the N‐wave is the sink of excitatory synaptic potentials produced in the superficial tectum, and predictions relating unitary firing to the field potential profile are made.
Types of unitary response and correlation with the field potential profile during activation of the avian optic tectum
Authors: Holden A. L. 
Published: December 2014

1. Unitary responses were recorded in the lateral tectum of the pigeon, with electrolyte‐filled micropipettes after electrical stimulation of the optic nerve‐head.2. Optic nerve fibre spikes could be recognized by their conformation, fixed latency, brief recovery times, and location in the superficial tectum. Their action potentials were either triphasic with a prominent second phase, or monophasic positive.3. The optic nerve consists of small myelinated fibres conducting at 5·3‐8·0 m/sec. These axons probably have diameters in the order of 1·6‐2·2 μ.4. The fibre spikes were localized to the N‐zone and R‐zone. None was recorded deeper. Most of the fibre spikes preceded the tectal N‐wave.5. One hundred and fifty‐six post‐synaptically fired cells were recorded. These had a diphasic positive‐negative conformation, and were fired at variable latency.6. One hundred and forty of these cells fired a single spike to each stimulus to the optic nerve‐head. Even the most stably fired cells could be proved to be trans‐synaptically activated by the evidence of non‐collision.7. Sixteen of the 156 cells fired repetitively to single stimuli to the optic nerve‐head.8. Evidence could be obtained that afferent inhibition operates upon tectal cells.9. Cells in the N‐zone were fired earliest in the 3 msec interval, corresponding to the rising phase of the tectal N‐wave. By comparison, cells in the P‐zone were not fired in the 3 msec interval, and the proportion fired in the 4 msec interval was reduced. Cell firing in the P‐zone must be produced by tectal interneurones.10. Cells were present in the N‐zone with recovery times below 5 msec. No cells in the P‐zone had recovery times below 5 msec.11. A clear correlation could be made between the distribution of fibre and cell spikes, and the field potential profile. A correlation could also be made between the timing and recovery time of cells in the N‐zone and P‐zone. The unitary records show that the tectum is activated radially by the retinotectal pathway.
The effects of depolarization of motor nerve terminals upon the release of transmitter by nerve impulses
Authors: Hubbard J. I. , Willis W. D. 
Published: December 2014

1. Depolarizing currents were applied to motor nerve terminals in the rat phrenic nerve—diaphragm muscle preparation in vitro.2. During the passage of depolarizing currents the amplitude of the presynaptic nerve action potentials and of end‐plate potentials (e.p.p.s) was reduced in proportion to the current strength.3. The reduction in e.p.p. amplitudes was shown to be due to a reduction in the number of quanta released.4. An excess of Mg ions or the previous application of a hyperpolarizing current could prevent the reduction of e.p.p. amplitudes and quantal contents by depolarizing current.5. Depolarizing current application prevented later hyperpolarizing currents affecting e.p.p. amplitudes.
The release of 5‐hydroxytryptamine from rabbit small intestine in vitro
Authors: Gwee M. C. E. , Yeoh T. S. 
Published: December 2014

1. A method is described by which the lumen of intestinal segments may be perfused separately and simultaneously under identical conditions of perfusion pressure and temperature, and the rate of appearance of 5‐hydroxytryptamine (5‐HT) into the serosal fluid measured.2. 5‐HT appeared in the serosal fluid from quiescent segments of rabbit intestine at a rate of about 4·0 ng/cm intestine/hr and about 14·0 ng/cm intestine/hr from segments performing active peristaltic movements.3. For both quiescent and active segments, when the perfusion fluid contained a monoamine oxidase inhibitor, nialamide (Niamid), the rate of appearance of 5‐HT was increased and if, in addition, 5‐HT was present in the perfusion fluid the rate of appearance of 5‐HT in the serosal fluid was even greater.4. The rate of appearance of 5‐HT from the intestine of rabbits pretreated with reserpine was about 0·8 ng/cm intestine/hr and Niamid only slightly increased this rate. However, if 5‐HT as well as Niamid were present the rate of appearance of 5‐HT was about 6·0 ng/cm intestine/hr.5. Possible explanations for these findings are discussed.
The effect of small hydrostatic pressure gradients on the rate of active sodium transport across isolated living frog‐skin membranes
Authors: Nutbourne D. M. 
Published: December 2014

1. The rate of active sodium transport across living isolated skins from Rana temporaria was measured when the skins were bulged inwards and outwards by small constant hydrostatic pressure gradients and by pushing them mechanically in the absence of such gradients. The effect of pressure gradients in the absence of bulging was also studied.2. An apparatus was designed to circulate Ringer solution to each side of the skin at constant temperature, flow and pressure. The pressures were controlled to within 0·5 mm H2O.3. It was found that bulging the skins in the absence of hydrostatic pressure gradients had no effect on sodium transport but that pressure gradients of less than 5 mm H2O had a marked effect, increasing transport when the pressure was higher on the outside of the skin, and decreasing it when the pressure was higher on the inside.4. It is concluded that increasing surface area does not influence sodium transport, whereas small hydrostatic pressure gradients have a marked effect.5. Possible causes for this phenomenon are discussed and its significance is considered with special reference to sodium reabsorption from the proximal tubule of the kidney.
The effect of hypo‐ and hypertonic solutions on volume and ion distribution of smooth muscle of guinea‐pig taenia coli
Authors: Brading Alison F. , Setekleiv J. 
Published: December 2014

1. The intra‐ and extracellular spaces and ionic content of the taenia coli of the guinea‐pig have been measured in a series of bathing solutions in which the tonicity varied from 0·5 to 3 times the tonicity of the normal Krebs solution.2. Equilibrium of the tissue in the experimental solution is reached within about 30 min.3. The absolute values of the parameters measured have been shown to depend on the blotting technique used. These differences were eliminated by expressing the results as a percentage of the values found in the normal Krebs solution.4. In hypertonic solutions the cell behaves as a perfect osmometer, the cell volume changing in proportion to the tonicity of the bathing medium. Only a small amount of cations is lost from the cells. A considerable amount of chloride is lost, making the postulation of its replacement by some other anions necessary in order to maintain electroneutrality of the intracellular solution.5. In hypotonic solutions the cells do not behave as predicted for a perfect osmometer. In 0·5 hypotonic solution an actual decrease in cell volume was observed associated with an increase of the extracellular space probably due to penetration of [14C]sorbitol into the cell. The intracellular ionic concentration was decreased. These findings suggest damage of the cell membrane.6. The observed hyperpolarization of the membrane in hypertonic solution can be explained by the increased intracellular potassium concentration.
Response of the cat's pad eccrine sweat glands to intravascular injections of catecholamines
Authors: Foster K. G. 
Published: December 2014

1. Using a sensitive method for detecting and monitoring sweat secretion, a study has been made of the effects of adrenaline and noradrenaline on the cat's pad sweat gland activity in the anaesthetized cat.2. Intravenous or intra‐arterial injections of adrenaline or noradrenaline only very occasionally caused these glands to secrete.3. The predominant effect of these drugs on glands which are already secreting in response to plantar nerve stimulation is inhibitory.4. The catecholamine inhibition could be reduced or blocked by phentolamine, but not by propranolol, dibenamine or phenoxybenzamine.5. It is concluded that these glands can be directly activated by intravascular injections of adrenaline or noradrenaline, but that the inhibitory effect of concomitant vasoconstriction usually prevents a response being detected at the skin surface.
Degeneration secretion from parotid glands after section of the auriculotemporal nerves at different levels
Authors: Emmelin N. 
Published: December 2014

1. In cats under ether or hexobarbitone anaesthesia the auriculotemporal nerve was cut near the parotid gland on one side and 12‐20 mm more proximally on the other. After 22‐64½ hr the cats were anaesthetized with chloralose and the parotid ducts cannulated. Degeneration secretion of saliva which appears after post‐ganglionic parasympathetic denervation was found to start 2‐5½ hr later in the gland denervated proximally than in that denervated distally. It ceased, on the other hand, later in the former than in the latter gland.2. Before degeneration secretion had started spontaneously it could be provoked by intravenous injection of acetylcholine, methacholine, carbachol or eserine and the effect was more pronounced on the gland denervated distally. When it had ceased spontaneously it could also be provoked, and the effect on the other gland was now more marked.3. Earlier it has been assumed that while a nerve is degenerating there is a period when the nerve endings are unable to retain in a normal way acetylcholine still being synthesized. It is now suggested that this period starts later after proximal than after distal denervation because more of the material required for the normal function of the endings is available in a long piece than in a short piece of nerve.
Spectral properties of dark‐adapted retinal ganglion cells in the plaice (Pleuronectes platessa, L.)
Authors: Hammond P. 
Published: December 2014

1. Spectral, spatial and temporal properties of receptive fields of dark‐adapted, on—off retinal ganglion cells in the intact eye of the plaice, were analysed by recording from their axon terminals in the superficial layers of the optic tectum with indium micro‐electrodes.2. Two cell‐types were identified. The first gave fast‐adapting, spectrally opponent on—off responses without centre‐surround subdivisions of the receptive field. On and off response‐components were mutually antagonistic. The second type gave slow‐adapting on—off or off responses for different stimulus positions within the receptive field, with centre‐surround or adjacent field configurations. Only on—off centre cells, showing mutual antagonism between field centre and surround, or off centre cells with inhibitory centres, were found. These cells had weak opponent or non‐opponent properties.3. Most cells of each type received inputs both from cones and rods. At stimulus intensities suprathreshold for cones, response‐components gave spectral peaks which have been classified into one of four wave‐length ranges; blue, 440‐460 nm; blue‐green, 470‐490 nm; green, 510‐540 nm; and orange, 560‐590 nm. No cells analysed gave sensitivity maxima in the red. At low stimulus intensities all cells with rod input gave a single spectral peak between 510 and 530 nm.
Effect of sodium content on sodium efflux from human red cells suspended in sodium‐free media containing potassium, rubidium, caesium or lithium chloride
Authors: Maizels M. 
Published: December 2014

1. Human red cells treated with lactose solution and loaded with NaCl and BCl subsequently exchange cation with a nutrient BCl medium. B is the same in cells and medium, and is either K, Rb, Cs or Li. In these circumstances Na always moves outwards with the concentration gradient, but the efflux is largely active.2. With suspensions in media containing Ca2+, the total Na efflux depends on the amount of Na in the cells and on the nature of cation B. Thus for any given value of mean cell Na (Nam) in excess of 30 m‐equiv/l. cells, the effect of B on the amount of Na efflux is K > Cs > Rb > Li, while with Nam between 0·7 and 5 m‐equiv/l. cells, the sequence is Cs > Li > K, Rb. With Nam between 5 and 30 m‐equiv/l. cells, intermediate sequences may be demonstrated for the effects of B on Na efflux. This applies both to the efflux itself and to the flux: concentration ratio, FCR.3. FCR for passive Na efflux in these circumstances is determined by adding strophanthin G to the medium. It varies inversely with the duration of exposure to Ca2+ in the exchange and nutrient media, but not with the nature of cation B. FCR for passive efflux is probably little affected by the value of Nam.4. By deducting passive from total Na efflux, active Na efflux is obtained, and variations in the latter with cell Na content, and with B, result in FCR curves similar to those obtained with total Na efflux.5. Total and passive Na efflux have also been measured in Ca‐free media. Here the passive efflux is considerable, and with Na + K cells in KCl media FCR increases with Nam, but in other systems this change is not significant. However, the rate of passive efflux into LiCl media is less than that for KCl or CsCl media. Owing to the magnitude of passive flux in Ca‐free systems, the total Na efflux is also increased, but FCR for active Na efflux is quantitatively and qualitatively similar to that occurring in systems containing Ca2+.6. The effects of B and Nam on Na efflux give a series of sequences for B which recall some of those obtainable when chemically modified glass membranes separate solutions of salts, and which are attributable to the charge on the membrane and the hydration of the cations involved. However, certain sequences obtained with red cells do not occur with glass membranes. This difficulty is resolved if it be assumed that throughout the range of Nam (0‐80 m‐equiv/l. cells) active B influx at the external cell face modifies linked Na efflux according to the series K > Rb, Cs > Li, while with Nam between 0 and 30 m‐equiv/l. cells (and high complementary B), cations escaping passively compete with active efflux of Na inhibiting the latter according to the series K, Rb > Li > Cs. Both these series could theoretically be explained in terms of surface charges and hydration of cations.7. Li‐loaded cells in nutrient KCl or other media failed to show active Li efflux.
A note on transmembrane potential in dermal melanophores of the frog and movement of melanin granules
Authors: Martin A. R. , Snell R. S. 
Published: December 2014

1. Transmembrane potentials were measured and distribution of melanin granules observed in dermal melanophores of the isolated frog's web.2. In normal Ringer solution, melanin granules were aggregated in the cell bodies and the transmembrane potentials were usually in the range 70‐90 mV.3. Addition of alpha‐melanocyte stimulating hormone (α‐MSH) to the bathing solution resulted in dispersion of the melanin granules into the processes of the cells, without any accompanying change in membrane potentials. Altering the membrane potentials by changing the external K+ concentration had no effect on melanin migration.4. It is concluded that migration of melanin granules in these cells is unrelated to cell membrane polarization.
Cable properties of smooth muscle
Authors: Abe Y. , Tomita T. 
Published: December 2014

1. The cable properties of smooth muscle of guinea‐pig taenia coli were studied by intracellular recording of electrotonic potentials produced by square current pulses and alternating current applied with external electrodes.2. An electrical model of the smooth muscle was constructed to test how the junctional resistance between cells affected the cable properties. The model consisted of a series of short cables (representing cells) which were connected by junctional resistances.3. It was concluded, from the experiments on the living tissue and on the model, that the electrotonic potential in smooth muscle can be expressed by the ordinary cable equation used for nerve and skeletal muscle fibres, even though the junctional resistance is of the same order of magnitude as that of the myoplasmic resistance.4. The cable equation was used to analyse the membrane parameters from the electrotonic potential, from the time course of the foot of the spike and from the conduction velocity. The analysis indicates that the smooth muscle has a membrane capacity of 2‐3 μF/cm2 and a membrane resistance of 30‐50 kΩ cm2.