bluuebunny/crossref_metadata_2025 huggingface dataset:
Colour‐coded ganglion cells in the goldfish retina: extension of their receptive fields by means of new stimuli
Authors: Daw Nigel W.
Published: December 2014

1. Receptive fields of colour‐coded ganglion cells of the goldfish retina were investigated.

2. Only a few cells (5%, Type P) were found to be as simple as those described by Wagner, MacNichol & Wolbarsht (1960, 1963), with an ‘on’ response to red light in the centre, and an ‘off’ response to green light over a rather wider area, or vice versa.

3. Most cells (49%, Type O) also gave a peripheral response with an ‘on’ response to green light, and an ‘off’ response to red light in the periphery, as well as an ‘on’ response to red light and an ‘off’ response to green light in the centre (or vice versa).

4. When a small spot of light was used to stimulate the periphery of a Type O cell, the peripheral response usually was not obtained. The organization of the periphery is such that a stimulus of large area and low intensity (annulus) is much more effective than a stimulus having equal energy with small area and high intensity (spot). If only small spots are used, the Type O cell is indistinguishable from the Type P cell.

5. Spectral sensitivity measurements show that one central and one peripheral process are fed primarily by red‐absorbing cones, and the other central and the other peripheral process by green‐absorbing cones or rods.

6. The diameter of the receptive field as a whole is very large, being 5 mm or more on the retina.

7. When red spots in green surrounds, or red/green boundaries are used as stimuli, the response can be predicted by summing the responses to the components of the stimulus.

8. This type of receptive field organization is appropriate to mediate simultaneous colour contrast. The ‘opponent colour’ organization previously reported is appropriate for successive colour contrast, but not for simultaneous colour contrast.

9. The component of the response coming from the green‐absorbing cones was masked or hidden by the component of the response coming from the red‐absorbing cones in 14% of the units (Type Q units). The component from the green‐absorbing cones was revealed by using a high intensity of stimulation, or by observing the response after bleaching pigment with an intense red light.
Osmotic stability of blood platelets
Authors: Fantl P.
Published: December 2014

1. Hypotonic solutions added to human platelet‐containing plasma cause a transient decrease of absorbancy of light at 610 mμ which is followed by a gradual increase of absorbancy.

2. When platelets are stored for 7 hr at 4° C the absorbancy changes with variations of osmolarity and their aggregation with adenosine diphosphate (ADP) remain the same. However, the reversal of absorbancy declines during storage of platelet‐containing plasma.

3. Platelets are not aggregated by stearate. Platelets appear to be only slightly affected by stearate concentration higher than 0·8 m
M, but oleate has no effect.

4. Hypertonic solutions of NaCl and urea cause increase in absorbancy of platelet‐containing human plasma. Hypertonic sucrose solutions produce no more change than isotonic solutions. Hypertonic NaCl produces permanent increases in absorbancy. In human platelet‐containing plasma the increased absorbancy caused by hypertonic urea is transient and declines.

5. The osmotic platelet changes occur in isolated platelets as well as in platelet‐containing plasma.

6. The absorbancy of frozen and thawed platelet‐containing plasma is not significantly altered by hypotonic solutions but the absorbancy changes caused by hypertonic solutions are similar to that of unfrozen plasma.

7. The immediate absorbancy changes caused by hypo‐ and by hypertonic solutions are the same at 5° C and 30° C and are therefore probably of a physical nature. The reversal of absorbancy and aggregation of platelets by added adenosine diphosphate have Q10 > 1 and are therefore probably of a chemical‐enzymic nature.

8. Divalent cations and contact activation are not required for the osmotic platelet changes and 10μ3
M‐Cu2+ and Zn2+ do not interfere. Inhibitors of oxidative phosphorylation, electron transfer, sodium, potassium activated adenosine triphosphatases and adenosine triphosphate do not inhibit reversal of absorbancy of platelets exposed to hypotonic solutions. Cyanide, 5 × 10μ3
M, fluoride, 1·23 × 10μ2
M, iodoacetamide, 10μ2
M, are moderately effective inhibitors. At hydrogen ion concentrations above pH 8, complete inhibition occurs.

9. N‐ethyl‐maleimide, 10μ3
M, and mercloran inhibit completely reversal of absorbancy, indicating the necessity for sulphydryl compounds.

10. Intact platelets are essential for the reversal of absorbancy after hypotonic swelling. Osmotic changes by hypotonic solutions are independent of ADP aggregation of platelets.
The angular selectivity of visual cortical cells to moving gratings
Authors: Campbell F. W. , Cleland B. G. , Cooper G. F. , Enroth-Cugell Christina
Published: December 2014

1. Grating patterns were used to obtain a quantitative description of cells in the visual cortex of the cat whose response amplitude depended critically upon the orientation of the moving grating.

2. In all such cells the impulse frequency was found to decrease linearly with angle on either side of an optimum angle (the preferred angle) until the response fell to zero or to a base frequency. The angular rate of change of response varied between cells and was expressed as the half‐width at half amplitude (the angular selectivity).

3. The angular selectivity of thirty‐five cells was determined and more than half (nineteen) of these fell within the range 14‐26°.

4. Fourteen cells responded optimally only when the grating was moved in one direction. Twenty‐one cells responded optimally to two directions of movement 180° apart, but the response in the two directions was not always equal.

5. No significant correlation was found between the response amplitude at the optimum angle and the angular selectivity.

6. The distribution of preferred angles did not show any difference between the oblique orientations and the vertical and horizontal orientations.

7. These results are compared with a previous psychophysical estimate of angular selectivity.
Diuretic responses to water‐load in four strains of mice
Authors: Stewart J.
Published: December 2014

1. The kinetics of excretion of water, sodium and potassium following a stomach load of water, with and without an initial injection of vasopressin, are described in each of four strains of mice: RAP, CBA/FaCam, Peru and A/Cam.

2. In general there was a diuretic lag followed by an increase in the rate of excretion of water to a maximum, after which the rate of excretion fell again to near resting levels. The rate of excretion of sodium rose to an initial maximum which significantly preceded the maximum rate of water excretion. The rate of excretion of sodium then fell to a minimum at a time not significantly different from the time of maximum rate of water excretion.

3. The effect of an initial injection of vasopressin was to increase and to prolong the initial rise in rate of sodium excretion. The maximum rate of water excretion and the minimum sodium concentration were delayed, but the levels eventually reached were not significantly altered, by the vasopressin injection.

4. The strains of mice differed significantly in diuretic lag, maximum rate of diuresis, and 3 hr excretion of water and electrolytes.

5. The strains also differed significantly in the effects of vasopressin, both in increasing diuretic lag and in increasing sodium excretion. There was no correlation between the antidiuretic and natriuretic effects of vasopressin.
The influence of hypothalamic temperature and ambient temperature on thermoregulatory mechanisms in the pig
Authors: Baldwin B. A. , Ingram D. L.
Published: December 2014

1. Two types of temperature fluctuation have been recorded from the preoptic region of the conscious pig. One, which is associated with arousal or movement, and another, which is related to rhythms in respiration and blood pressure.

2. When the pigs were subjected to infra‐red irradiation at various ambient temperatures it was found that there was no precise temperature of the preoptic region at which the respiratory frequency increased.

3. Local heating of the preoptic region was effective in increasing the respiratory frequency only when the ambient temperature was above 30° C.

4. Even when both the peripheral temperature and central temperatures were increased there was a delay of several minutes before the onset of panting.

5. Cooling the preoptic region of the hypothalamus prevented the onset of panting in a hot environment, and reduced respiratory frequency in an animal which was already panting.

6. Oxygen consumption was reduced in a cold environment when the preoptic region was warmed, and increased when it was cooled. No increase in oxygen consumption occurred when the hypothalamus was cooled in a hot environment.
Finger blood flow in Antarctica
Authors: Elkington E. J.
Published: December 2014

1. Finger blood flow was estimated, by strain‐gauge plethysmography, before and during a 1 hr immersion in ice water, on twenty‐five men throughout a year at Wilkes, Antarctica. A total of 121 satisfactory immersions were made.

2. Blood flow before and during immersion decreased significantly in the colder months of the year, and the increase caused by cold‐induced vasodilatation (CIVD) became less as the year progressed. The time of onset, blood flow at onset, and frequency of the cycles of CIVD showed no significant relation to the coldness of the weather (as measured by mean monthly wind chill) or the time in months. Comparisons of blood flow before and after five field trips (average duration 42 days), on which cold exposure was more severe than at Wilkes station, gave similar results.

3. The results suggest that vasoconstrictor tone increased. This interpretation agrees with previous work on general acclimatization in Antarctica, but contrasts with work elsewhere on local acclimatization of the hands.
Intracellular recording from mammalian superior cervical ganglion in situ
Authors: Erulkar S. D. , Woodward J. K.
Published: December 2014

1. Recordings have been obtained by intracellularly placed microelectrodes from cells of the superior cervical ganglion of the rabbit. The ganglion was left in situ.

2. In response to stimulation of the external carotid nerve, some cells responded with a single spike of short latency followed by a long‐lasting hyperpolarization. These cells, presumably, were activated antidromically. The majority of cells, however, responded with an early spike followed by a long‐lasting depolarization; superimposed on this depolarization were one or two spikes with latencies from 35 to 70 msec. Anatomical pathways responsible for this activation have been suggested.

3. A variety of responses were recorded from different neurones when the preganglionic sympathetic trunk was stimulated. Many of the cells responded to maximal stimulation of the nerve with repetitive spikes. Stimuli of constant strength could elicit variable responses from a single neurone. This variability and the multiple spike response may be due to multiple pathways leading to the same cell and the possibility of the presence of internuncial neurones in the ganglion is suggested.

4. Strong stimulation of the preganglionic sympathetic nerve trunk caused inhibitory effects at the ganglion cells.

5. Direct stimulation of the ganglion cells through the recording microelectrode elicited only one spike even at high intensity. Thus the multiple spike response to orthodromic stimulation must have been due to a temporally dispersed afferent input.

6. It is concluded that the organization of the rabbit superior cervical ganglion is more complex than has been suspected previously, and that integration as well as transmission takes place at the level of these neurones.
Tension due to interaction between the sliding filaments in resting striated muscle. the effect of stimulation
Authors: Hill D. K.
Published: December 2014

1. A resting sartorius muscle of the frog or toad possesses a special kind of elasticity which is shown to be due to a component lying between the two sets of filaments. The elastic effect is seen only for very small length changes, up to about 0·2% of the muscle length, and the ‘elastic limit’ is then reached. If the length change then continues at a constant velocity the tension developed is maintained at a fixed level, producing a sort of frictional resistance. The component responsible is called the ‘short‐range elastic component’, or SREC.

2. It is also shown that a small part of the permanent tension of a resting muscle is probably due to ‘active’ interaction between the filaments. This is called the ‘filamentary resting tension’, or FRT. For a sarcomere length of 2·0 μ the FRT amounts to about 150 mg in a muscle weighing 100 mg.

3. The stiffness of the SREC and the magnitude of the FRT are shown to be related to one another. They are both increased, and may rise to high values, by making the external solution hypertonic.

4. The working hypothesis is as follows. In a resting muscle the cross‐bridges on the myosin filaments are not entirely inactive, but a very small proportion of them are cross‐linked with the actin filaments. The links are very stable and have a long ‘life’. The elastic behaviour is due to the flexural rigidity, or spring‐like properties of these bridges. The elasticity is ‘short‐range’ because the bridges can be bent, or stretched, only a small way from the steady‐state position before the contacts ‘slip’. The ‘filamentary resting tension’ (which is present in the absence of any external length change) is attributed to an ‘active process’, which operates by imparting ‘organized’ potential energy to the participating cross‐bridges, by potentiating their attachment, against their elastic resistance, to sites on the actin filaments which are displaced towards the Z line.

5. It is shown that the ability of the muscle to maintain a ‘frictional’ resistance to a continuing, slow, length change is suppressed during a maintained tetanic contraction. The process of suppression starts during the period of the latency relaxation.

6. It is suggested that the latency relaxation may be due to a reduction of the filamentary resting tension.

7. The experiments with the latency relaxation were facilitated by the use of strongly hypertonic solutions. The positive twitch tension is then greatly reduced, or may be practically abolished, while the latency relaxation remains at about its normal size and is extended in duration.
Termination and functional organization of the dorsal spino‐olivocerebellar path
Authors: Oscarsson Olov
Published: December 2014

1. The spino‐olivocerebellar path ascending through the dorsal funiculus (DF‐SOCP) was investigated in decerebrate cats with the cord transected in the third cervical segment except for the dorsal funiculi. The climbing fibre responses evoked in Purkinje cells were studied by recording the mass activity at the cerebellar surface and by recording from single cells.

2. The DF‐SOCP forms a disynaptic path from the spinal cord to the cerebellar cortex as shown by latency measurements. Anatomical studies have recently demonstrated that the relays are in the rostral part of the dorsal funiculus nuclei and in the dorsal accessory olive.

3. The DF‐SOCP projects to sagittal zones in the pars intermedia and vermis of the anterior lobe. The somatotopical organization is predominantly transverse in the pars intermedia and predominantly longitudinal in the vermis.

4. The olivary neurones in the DF‐SOCP are activated by the flexor reflex afferents from wide receptive fields. The fields are restricted to one ipsilateral limb and the majority of the olivary neurones could be activated from all the nerves tested in this limb.

5. Natural stimulation of receptors evoked excitation in about half of the olivary neurones investigated. This excitation was elicited by pressure against deep structures. Inhibitory effects were rarely observed.

6. The dorsal and ventral spino‐olivocerebellar paths are compared.
Evaporative water loss in the new‐born baby
Authors: Hey E. N. , Katz G.
Published: December 2014

1. Measurements of total evaporative water loss (EWL) were made on sixty‐three premature and full‐term babies 0‐65 days after birth within a closed Perspex chamber under varied environmental conditions by measuring the flow and absolute humidity of air entering and leaving the chamber. Control experiments suggested that the method underestimated loss by about 5%. Measurements of O2 consumption were made concurrently by recording the volume change of the closed gas circuit.

2. The total basal EWL averaged 10·8 g H2O/m2.hr in infants 2‐10 days old when ambient water vapour pressure (PH2O) was 18 mm Hg; basal EWL was correlated with basal metabolic rate at all ages studied and evaporative heat loss accounted for ∼ 23% of basal heat production.

3. Respiratory water loss was measured by detecting the water added to air at 33° C passed across the face of eight infants in a trunk plethysmograph. Respiratory water loss was inversely related to the water vapour content of the inspired air; gas appeared to leave the nose ∼ 95% sat. at 35·6° C.

4. Measurements of total EWL were obtained when humidity was varied and skin loss was calculated by subtracting estimated respiratory loss from total loss; changing PH2O from 7 to 25 mm Hg appeared to decrease basal skin water loss by only 1·5 g/m2.hr.

5. No consistent changes in EWL were obtained when environmental temperature (TE) was varied between 28 and 34° C. Active sweating occurred in infants 0‐10 days old born within 3 weeks of term when TE exceeded 34‐35° C and rectal temperature (TR) rose above 37·2° C. The threshold rectal temperature at which sweating was detected fell significantly in the first 10 days of life; EWL increased two to fourfold when TR rose to between 37·5 and 37·8° C.

6. In infants of less than 215 days post‐conceptual age (term ∼ 268 days) EWL increased less than 50% at TR 37·7‐37·8° C; it is concluded that the sweating mechanism is defective in these infants.
Biophysical and mechanical properties of red and white muscle fibres in fish
Authors: Hidaka T. , Toida N.
Published: December 2014

1. The electrical properties of red muscle fibres of the silver carp (Carassius auratus (Linné)) were investigated and compared with those of white fibres. The resting membrane potential of red muscle was −73·1 mV, and of white muscle −82·4 mV. The effective resistance of fibre, time constant and space constant were 1·43 MΩ, 26·6 msec and 2·1 mm for red muscle and 1·0 MΩ, 48·4 msec and 1·9 mm for white muscle.

2. The membrane capacitance in red muscle was 2·55 μF/cm2 and in white muscle was 7·23 μF/cm2, though the sarcoplasmic reticulum and the transverse tubular system were developed equally in both tissues.

3. No rectification could be observed in the current—voltage relation in both the muscles. However, in excess potassium solutions, both types of muscle showed anomalous rectification.

4. In red muscle it was rare to trigger a spike by nerve stimulation or by field stimulation of the tissue. However, in white muscle, there appeared graded responses and occasionally spikes were generated with overshoot potentials.

5. Excess potassium concentration produced contracture in the red muscle, but even forty times of normal potassium never produced contracture in the white muscle.
Changes in contractile properties of disused soleus muscles
Authors: Fischbach Gerald D. , Robbins Norman
Published: December 2014

1. The hypothesis that the pattern of activity of muscle can determine its contractile properties was tested in the case of the rat soleus subjected to chronic disuse.

2. In order to characterize the pattern of motor activity over long periods of time, a method of chronic EMG recording with indwelling electrodes was developed. Some characteristics of the EMG recorded from unrestrained animals are described.

3. Immobilization of the knee and ankle joints reduced aggregate EMG activity in the soleus to 5‐15% of control and resulted in a shift from tonic to a more phasic pattern of firing.

4. After 4 weeks of immobilization, speeding of the soleus mechanical properties was indicated by: shortened contraction time; decreased tetanus/twitch ratio; increased maximum rate of development of tetanic tension; and decreased fusion during a 5/sec tetanus.

5. Because the contractile properties of the soleus can be altered by a period of disuse with no change in innervation, neuronal control of the contractile mechanism depends in part on impulse activity.
Sodium influxes in internally perfused squid giant axon during voltage clamp
Authors: Atwater I. , Bezanilla F. , Rojas E.
Published: December 2014

1. An experimental method for measuring ionic influxes during voltage clamp in the giant axon of Dosidicus is described; the technique combines intracellular perfusion with a method for controlling membrane potential.

2. Sodium influx determinations were carried out while applying rectangular pulses of membrane depolarization. The ratio ‘measured sodium influx/computed ionic flux during the early current’ is 0·92 ± 0·12.

3. Plots of measured sodium influx and computed ionic flux during the early current against membrane potential are very similar. There was evidence that the membrane potential at which the sodium influx vanishes is the potential at which the early current reverses.
The regularity of primary and secondary muscle spindle afferent discharges
Authors: Matthews P. B. C. , Stein R. B.
Published: December 2014

1. The patterns of nerve impulses in the afferent fibres from muscle spindles have been studied using the soleus muscle of the decerebrate cat. Impulses from up to five single units were recorded simultaneously on magnetic tape, while the muscle was stretched to a series of different lengths. Various statistics were later determined by computer analysis.

2. After the ventral roots were cut to eliminate any motor outflow to the muscle spindles, both primary and secondary spindle endings discharged very regularly. At frequencies around 30 impulses/sec the coefficient of variation of the interspike interval distributions had a mean value of only 0·02 for the secondary endings and 0·058 for the primary endings. The values obtained for the two kinds of ending did not overlap.

3. When the ventral roots were intact, the ‘spontaneous’ fusimotor activity considerably increased the variability of both kinds of endings. Secondary endings still discharged much more regularly than primary endings, even when the fusimotor activity increased the frequency of firing equally for the two kinds of endings. At frequencies around 30/sec the average coefficient of variation of the interval distributions was then 0·064 for the secondary endings and 0·25 for the primary endings.

4. When the ventral roots were intact there was usually an inverse relation between the values of successive interspike intervals. The first serial correlation coefficient often had values down to — 0·6 for both kinds of ending. Higher order serial correlation coefficients were also computed.

5. Approximate calculations, based on the variability observed when the ventral roots were intact, suggested that when the length of the muscle was constant an observer analysing a 1 sec period of discharge from a single primary ending would only be able to distinguish about six different lengths of the muscle. The corresponding figure for a secondary ending was twenty‐five lengths.

6. The increase in variability with fusimotor activity, and the pattern of serial correlations, were probably caused by static fusimotor fibres firing at rates below the fusion frequency of the intrafusal muscle fibres that they supply.
Osmotic concentration of the gastric juice of dogs
Authors: Altamirano M. , Izaguirre Elizabeth , Milgram E.
Published: December 2014

1. The freezing point of the gastric juice, produced by histamine stimulation in anaesthetized dogs, of the arterial plasma and of the plasma obtained from a gastric vein were measured.

2. The osmolality of the blood that passes through the gastric mucosa increases during secretion of acid juice.

3. The amount of water that should be removed from the arterial plasma to obtain a solution isosmolal to the gastric venous plasma is equivalent to the amount of water required to dilute the secreted H+. From this result it is concluded that the increase of osmolality of the venous plasma is a consequence of the clearance of water free of solute by the gastric mucosa.

4. The gastric juice was hyposmotic to the venous plasma in twenty out of thirty dogs, being isosmotic to that plasma in seven dogs. Even in the last group of animals, the gastric secretion might be considered as slightly hypotonic to the venous blood that passes through the secretory part of the mucosa.

5. Considerations based on available data suggest that the ‘primary’ acid juice is usually hyposmotic to the extracellular fluid in the vicinity of the oxyntic cells.
Rod increment thresholds on steady and flashed backgrounds
Authors: Hallett P. E.
Published: December 2014

1. This paper presents increment threshold data for a fairly wide range of parameters but certain of the relationships are slightly complicated by what may amount to large differences in the observers’ criterion. The following paper deals with a very limited range of parameters but the measurements are more precise and the analysis more simple.

2. Increment thresholds have been measured for a small, brief duration test viewed against large steady and pulsed backgrounds, using the technique of Aguilar & Stiles (1954) which is intended to isolate rod vision. Under these circumstances it is shown that the test is seen by the rods and that the cones do not disturb the sensitivity of the rods.

3. The relative positions of increment threshold curves for steady and pulsed backgrounds are usually consistent with an integration time of τ = ca. 0·1 sec.

4. Backgrounds of less than 0·1 sec duration are effectively impulse inputs in the sense that the magnitude and time course of the test threshold disturbance (‘impulse function’) is dependent only on background energy.

5. Functions of the impulse function may be substituted for the classical integration time τ. The exact form of the impulse function and its theoretical treatment is pursued in the next paper.

6. The threshold disturbance caused by switching on a background light settles to a steady value within 2 to 3 times τ.
Maternal placental and myometrial blood flow in the pregnant rabbit
Authors: Duncan Sheila L. B. , Lewis B. V.
Published: December 2014

1. In anaesthetized rabbits 27–29 days pregnant (term is 31 days) uterine blood flow was measured in an extracorporeal loop between a carotid and the central end of an external iliac artery, the descending aorta and its other branches being tied. Mean flow was 45 ± 2 ml. min−1, or 105 ± 4 ml. min−1 per kg uterus and contents in thirty‐four litters.

2. The partition of uterine blood flow to placentas (∼ 60%), myometrium (∼ 27%) and vagina (∼ 13%) as estimated by injection of isotopelabelled microspheres of 35 or 50 μ diameter, was similar in intact rabbits and in those with an extracorporeal loop.

3. Maternal blood flow was greater to the placentas of larger foetuses both absolutely and per unit placental weight. Flow to the placentas of dead foetuses was much less than to those of live foetuses, but flow to the adjacent myometrium was not decreased.

4. Maternal hypoxaemia (Pa, O2 ∼ 40 mm Hg) caused vasoconstriction in the uterine vascular bed after 3‐4 min. The distribution of blood flow within the uterus was altered, the placental fraction falling to 32%. This was unaffected by carotid denervation.

5. These observations suggest that there are large differences in the physiological control of maternal blood flow to the placenta, myometrium and vagina.
Control of body temperature in the unanaesthetized monkey by cholinergic and aminergic systems in the hypothalamus
Authors: Myers R. D. , Yaksh T. L.
Published: December 2014

1. In the unanaesthetized rhesus monkey, 5‐hydroxytryptamine (5‐HT), catecholamines, acetylcholine or carbachol were micro‐injected in a volume of 1·0 μl. or less through chronically implanted cannulae at eighty‐six sites in the hypothalamus.

2. 5‐HT in doses of 2‐10 μg caused a long‐lasting elevation in temperature which was dose‐dependent. An anatomical ‘mapping’ of the hypothalamus revealed that the hyperthermic action of 5‐HT was localized to the anterior, pre‐optic area directly ventral to the anterior commissure.

3. Noradrenaline in doses of 1‐12 μg produced a dose‐dependent fall in temperature of short duration. An anatomical ‘mapping’ showed that the hypothermic action of this and other catecholamines was again localized to the anterior, pre‐optic region.

4. Acetylcholine, alone or in a mixture with eserine, or carbachol caused a dose‐dependent hyperthermia which was characterized by an intense rise of short duration and vigorous shivering. A ‘mapping’ of this response revealed a diffuse patterning of sites throughout the hypothalamus which were sensitive to the application of acetylcholine and carbachol. However, in one circumscribed region at the junction between the posterior hypothalamus and mesencephalon, the two cholinomimetic substances caused a marked fall in temperature.

5. We conclude that 5‐HT activates a cholinergic heat production pathway which projects from the anterior to posterior hypothalamus. Noradrenaline, on the other hand, blocks the hyperthermic action of 5‐HT rather than activates the heat loss system. A chemically mediated heat loss pathway apparently does not exist in the hypothalamus.
The role of glandular activity in the electrical response of amphibian skin to noradrenaline
Authors: House C. R.
Published: December 2014

1. The electrical response of isolated amphibian skins to the presence of 4 × 10−5
M noradrenaline in the inner medium has been studied.

2. The response to noradrenaline consists of a transient secretion from the skin glands, a transient increase in the short‐circuit current, a transient decrease in the skin resistance and a partial depolarization of the skin potential (inside surface becoming less positive) followed by a hyperpolarization.

3. The origin of the initial depolarizing phase of the response to noradrenaline has been studied.

4. It is considered that the initial depolarization results partially from an increase in the chloride permeability of the outer membranes of the epithelial cells and predominantly from the emergence of an additional transient shunt pathway in the skin.

5. It is proposed that during secretory activity the skin glands constitute the transient shunt pathway responsible for the initial depolarizing phase of the response to noradrenaline.
Intracellular recordings from ganglia of the thoracic sympathetic chain of the guinea‐pig
Authors: Blackman J. G. , Purves R. D.
Published: December 2014

1. Intracellular recordings have been obtained from cells of thoracic paravertebral sympathetic ganglia of guinea‐pigs.

2. Resting potentials were 50–70 mV. The steady‐state current—voltage curve was linear for all hyperpolarizations and usually for depolarizations up to 10 mV. The slope of this curve was 19–186 MΩ (mean 55 MΩ). Time constants of cells were 6–14 msec (mean 9·1 msec).

3. Most cells maintained a high rate of firing of action potentials during strong current pulses.

4. Indirect stimulation via the rami communicantes or the interganglionic nerves of the sympathetic chain evoked a graded synaptic response which could lead to the discharge of one or more action potentials. Hexamethonium blocked the responses to such stimulation. Occasionally an all‐or‐none response remained, apparently conducted antidromically along the cell's axon.

5. Spontaneous synaptic potentials were observed. Their occurrence frequency was increased during indirect stimulation. If they are assumed to represent single quanta of release of transmitter, the quantal content of a threshold synaptic potential was 8–20 quanta.

6. Preganglionic fibres could ascend at least three segments or descend two after entering the sympathetic chain. They had conduction velocities of 0·1–1·1 m/sec.

7. Inexcitable cells were frequently impaled. Repetitive indirect stimulation gave rise in these cells to a large (20 mV) slow depolarizing response.
The spatial selectivity of the visual cells of the cat
Authors: Campbell F. W. , Cooper G. F. , Enroth-Cugell Christina
Published: December 2014

1. Micro‐electrode recordings have been made from single units in the visual cortex of the cat, during stimulation by moving grating patterns generated on a cathode ray tube.

2. The responses of the units have been measured in terms of either the frequency of impulses, or the contrast sensitivity, and expressed as a function of the spatial frequency of the grating pattern.

3. The amplitude of the responses recorded from cortical cell bodies was dependent upon the orientation of the moving grating, and for these units the stimulus was always presented at the preferred orientation. The response amplitude of other units did not depend upon the orientation of the grating stimulus, and these are believed to be the terminations of geniculate fibres.

4. The high spatial frequency end of the response function measured in terms of the contrast sensitivity could be well fitted by an exponential function. Subtraction of the blank count from the impulse frequency data gave a curve fitted by the same exponential function. The low frequency end was less consistent.

5. The spatial frequency at which this exponential function had fallen by one log. unit was taken to specify the position of the unit's response in the spatial frequency spectrum. For all units these values cover a range of four octaves of spatial frequency (from 0·18 to 3·8 cycles per degree).

6. It is suggested that these neurophysiological results support psychophysical evidence for the existence in the visual system of channels, each selectively sensitive to a narrow band of spatial frequencies.
Activity of lung irritant receptors in pulmonary micro‐embolism, anaphylaxis and drug‐induced bronchoconstrictions
Authors: Mills Janet E. , Sellick Hilary , Widdicombe J. G.
Published: December 2014

1. Lung irritant receptors have been studied in rabbits by recording action potentials from single vagal nerve fibres. Some of the rabbits were bilaterally vagotomized, and some paralysed and artificially ventilated.

2. The receptors gave rapidly adapting irregular discharges on inflation and deflation of the lungs. Many were stimulated by insufflation of ammonia vapour into the lungs, and some by passage of a fine catheter into the right bronchial tree. The fibres had conduction velocities in the range 3·6–25·8 m/sec.

3. The receptors were strongly stimulated by intravenous injections of histamine acid phosphate, 25–100 μg/kg. The response was considerably reduced by previous injection of isoprenaline which also reduced the bronchoconstriction due to histamine.

4. The receptors were stimulated by intravenous injections of isoprenaline, phenyl diguanide and micro‐emboli, and by anaphylaxis induced in rabbits previously sensitized to egg albumin.

5. The receptor responses could not be closely correlated in size with simultaneous changes in total lung resistance, lung compliance, tidal volume or breathing frequency.

6. It is concluded that, in rabbits with intact vagus nerves, lung irritant receptors contribute to the reflex hyperpnoea and bronchoconstriction of the conditions studied.
Effect of barbiturates on ‘quantal’ synaptic transmission in spinal motoneurones
Authors: Weakly J. N.
Published: December 2014

1. Monosynaptic excitatory post‐synaptic potentials (EPSPs) produced in triceps surae motoneurones of the cat by stimulation of single afferent fibres in the muscle nerve were recorded with intracellular electrodes before and after the administration of thiopentone or pentobarbitone.

2. The average amplitude of the ‘unit’ EPSP was 0·11–0·21 mV and remained unchanged after the administration of the barbiturates (10 mg/kg,
I.V.).

3. Mean quantum content (m) ranged from 1·9 to more than 5 before drug administration. The m was reduced by thiopentone (10 mg/kg,
I.V.) and pentobarbitone (10 mg/kg,
I.V.) by 23·1 and 24·7% respectively.

4. The barbiturates, in the doses employed, produced no alterations in the input resistance of the motoneurone membrane or in the strength—duration relation obtained by passing depolarizing current pulses through the micro‐electrode.

5. It is concluded that the action of thiopentone and pentobarbitone, in the doses used, is confined to the presynaptic nerve terminals and results in a reduction in the amount of transmitter released by afferent impulses.
A circadian rhythm in the disappearance of thyroxine from the blood in the calf and the thyroidectomized rat
Authors: Nathanielsz P. W.
Published: December 2014

1. Many factors affect the rate of disappearance of thyroxine from the peripheral blood. The normal animal is exposed to these to differing extents throughout a 24‐hr day. Conflicting results have been described with regard to circadian variations in several parameters of thyroid physiology.

2. The disappearance of radioactive thyroxine from the blood has been followed in intact and thyroidectomized calves and thyroidectomized rats fed either at night or during the day.

3. When calves were fed during the day the rate of disappearance of thyroxine from the blood was significantly faster in the day than at night. When fed at night the nocturnal disappearance rate became faster than the diurnal rate.

4. The circadian rhythm persists in the thyroidectomized calf and is hence not solely a feature of hypothalamic, pituitary or thyroid function.

5. On a full diet (Oxo Ltd., diet 41 B) the faster disappearance of thyroxine from the blood occurs at night when rats feed at night and during the day when they feed during the day.

6. After bile‐duct ligation the faster disappearance still occurs in the period in which the animal is feeding. This occurs even if the diet is solely glucose. When feeding on pure glucose the effect is less marked.

7. The substitution of a glucose diet for a full oxoid diet (Oxo Ltd., diet 41 B) results in a fall of 33·5% in the over‐all disappearance rate in bile‐duct‐ligated animals.

8. These results show that feeding, and the processes associated with it, are important factors determining utilization of thyroxine. This is so even after the prevention of any biliary‐faecal loss of thyroxine.
Warm receptors in the nasal region of cats
Authors: Hensel H. , Kenshalo D. R.
Published: December 2014

1. Specific warm receptors in the nasal region of cats were studied by recording afferent impulses from single units dissected from the infraorbital nerve. In addition, a few cold fibres from the same region were examined.

2. Numerous warm fibres with spot‐like receptive fields were found on the back of the nose. They were not excited by mechanical stimulation.

3. Multi‐fibre strands serving this area responded to moderate warming with an increase of the integrated discharge.

4. At constant temperatures from 30° C on, single warm fibres showed a steady discharge with a regular sequence of impulses, the frequency of which rose steeply with temperature and reached a maximum between 45 and 47° C. At higher temperatures the frequency fell to zero.

5. Rapid warming caused a dynamic overshoot, rapid cooling a transient inhibition of the warm fibre discharge. The highest dynamic frequencies of single fibres were 200 impulses/sec.

6. For a large population of single warm fibres the average maximum of static activity was 36 impulses/sec at 46° C, whereas the cold fibre population had a maximum of 9 impulses/sec at 27° C.
The rate of the ‘root shift’ in eel red cells and eel haemoglobin solutions
Authors: Forster R. E. , Steen J. B.
Published: December 2014

1. We have measured the rate of the exchange of O2 between eel red blood cells and their suspending fluid in a modified Hartridge—Roughton continuous‐flow rapid‐reaction velocity apparatus using an oxygen electrode to follow the progress of the reaction.

2. The half‐times for the uncomplicated oxygenation and deoxygenation reactions in red cells at 24° C were approximately 0·025–0·08 sec.

3. The rate of the Root shift in cell suspensions varied widely, depending on the initial condition of the CO2‐bicarbonate buffer system in the suspending fluid, with the rate of oxygenation or deoxygenation of the intracellular haemoglobin as an upper limit.

(a) The most rapid Root shift was produced by a change in extracellular PCO2 with minimal contributions from CO2 hydration—dehydration reactions in the suspending fluid or from ion exchanges across the membrane, and had a half‐time as short as 0·040 sec.

(b) The slowest Root shift was produced by an increase in the extracellular lactic acid concentration in the absence of any form of CO2 or in the presence of acetazolamide. This process is presumed limited by the rate of H+ or OH− transfer across the membrane and had a half‐time in excess of 10 sec.

(c) The Root off‐shift produced by an increase in PCO2 plus a decrease in extracellular pH showed no significant trend as temperature was lowered from 30° to 11° C.

(d) The Root on‐shift produced by a decrease in PCO2 and increase in extracellular pH had a half‐time of 3 sec at 30° C, 9 sec at 24° C and 20 sec at 11° C. These changes appeared limited by the uncatalysed rate of extracellular CO2 hydration.

4. Root off‐ and on‐shifts in cell haemolysates at 24° C, produced predominantly by changing pH but with unavoidable subsequent readjustments of the CO2‐bicarbonate buffer systems, had an initial rapid phase with half‐times as low as 0·01 sec. However, the curves were not monotonic, although they became so in the presence of carbonic anhydrase, indicating partial rate limitation by CO2 reactions.
Release into the cerebral ventricles of substances with possible transmitter function in the caudate nucleus
Authors: Portig P. J. , Vogt Marthe
Published: December 2014

1. One caudate nucleus of the anaesthetized cat was superfused by perfusing the anterior horn of one lateral cerebral ventricle. The perfusates were examined for their content in acetylcholine (ACh), dopamine, homovanillic acid (HVA) and 5‐hydroxytryptamine (5‐HT), at rest and after a variety of stimuli.

2. When prostigmine was added to the perfusion fluid, ACh appeared in the effluent; its concentration tended to rise in the course of an experiment. Various afferent stimuli, all of which caused evoked responses recorded from the contra‐lateral caudate nucleus, increased the ACh content of the effluent. Effective stimuli were noise and electrical stimulation of afferent nerves or of certain regions of the brain including the ipsi‐lateral substantia nigra.

3. The dopamine content of the effluent was extremely low (of the order of 50 pg/min) at rest, but, on occasion, rose sharply when the substantia nigra was stimulated electrically with trains of pulses repeated once every 3 sec. The results were inconsistent.

4. Since dopamine in tissue is rapidly transformed enzymically into HVA, the appearance of this acid in the perfusate was examined.

5. At rest, HVA was found to appear in the effluent at a rate of 2‐8 ng/min. Its concentration was rapidly depressed by increasing the depth of anaesthesia.

6. Stimulation of the substantia nigra for periods of 3 or 4 min caused an increment in the HVA content of the effluent lasting 1 hr or more. It was frequently seen when two points of the substantia nigra were stimulated simultaneously, less regularly with only one stimulating electrode, and rarely if this was placed in the most caudal part of the substantia nigra.

7. These results strongly support the view that there is a dopaminergic nigro‐striatal pathway. The following assumption would explain the erratic appearance of dopamine and the long duration of increments in HVA: many of the axons originating in the substantia nigra end either in the putamen or in parts of the caudate nucleus which are far away from the ventricular surface; any dopamine released from these axons will not reach the ventricular surface at all, and HVA will, at best, reach it very slowly.

8. Small amounts of 5‐HT appeared in the ventricular perfusate, and the quantity rose after the administration of monoamine oxidase inhibitors. It was not increased by the type of stimuli used in this work to elicit the release of ACh or HVA.
Transvascular fluid balance in the lung
Authors: Lunde P. K. M. , Waaler B. A.
Published: December 2014

1. The transvascular fluid balance has been studied in isolated blood‐perfused lungs of rabbit and cat. During periods of left atrial pressure (LAp) elevation, changes in preparation weight were measured. In some experiments simultaneous recordings of changes in blood volume, as judged by changes in emitted radioactivity from 51Cr labelled red blood cells, were performed.

2. In nine out of eleven experiments, elevation of LAp by 5 mm Hg within a test period of 8 min resulted in new weight stability and thus apparently in the establishment of a new transvascular fluid equilibrium. In five of these eleven experiments weight stability was also obtained on elevation of LAp by 10 mm Hg. When LAp was elevated further, transvascular fluid equilibrium was not obtained, and a continuous and eventually progressive outward flux of fluid occurred.

3. In a preparation with the vasculature paralysed by papaverine in order to avoid vasomotor reactions, changes in plasma protein content caused immediate alterations in the weight slopes of the preparations. These alterations were interpreted as being due to changes in transvascular fluid transfer. Again new stable weights were obtained on moderate changes in plasma protein content.

4. New weight and transvascular fluid equilibria seemed to be reached as a result of very small transvascular fluxes of fluid. The transvascular fluid balance in the lung may thus be dynamically maintained as a result of such small fluxes of fluid. The Starling hypothesis could account for this balance, provided that a small shift of fluid can cause sufficiently marked alterations in the osmotic and/or hydrostatic pressure gradient across the wall of the exchange vessels.

5. The possible role of a small extravascular compartment with a high fluid colloid osmotic pressure is discussed in relation to transvascular fluid balance in the lung.
The effect of prolonged cold exposure on heat production in new‐born rabbits
Authors: Hardman M. J. , Hey E. N. , Hull D.
Published: December 2014

1. The rates of oxygen consumption and the colonic temperatures were monitored from birth in rabbits delivered by Caesarean section at term. The rates of oxygen consumption at 25 and 36° C rose over the first 12 hr of life.

2. Thirty rabbits were kept unfed in an environment of 25° C from birth. Extra oxygen consumption, in response to cold exposure, failed 24–34 hr later. Twenty‐four of these rabbits were allowed to recover in an environment of 36° C. The metabolic response to cold exposure did not return in those kept unfed or given glucose but those fed with rabbit's milk showed significant recovery when re‐exposed to cold 4 or 18 hr later.

3. The tissue glyceride content of brown and white adipose tissue and the liver were greatly reduced once the animals failed to respond to cold exposure and no significant rise was detected during the recovery period after a milk feed.

4. Another twelve rabbits were kept unfed in an environment of 36° C. These animals showed a poor metabolic response to cold exposure after 48 hr, although their brown adipose tissue was still replete with fat and the blood glucose rose to normal values during cold exposure.

5. These results suggest that an increase in oxygen consumption in response to cold exposure can occur even though brown adipose tissue is largely depleted of glyceride provided that an alternative supply of fuel is available. Glucose alone is not an adequate source of energy.