bluuebunny/crossref_metadata_2025 huggingface dataset:
Colour vision in blue‐cone ‘monochromacy’
Authors: Alpern M. , Lee G. B. , Maaseidvaag F. , Miller S. S.
Published: December 2014

1. Atypical (blue cone) monochromats show two action spectra when tested by the increment threshold method of Stiles with ‘central’ fixation. One spectrum peaks near 450 nm and has the spectral characteristics of normal blue cones. The other resembles rhodopsin (π0) modified slightly by photostable macular pigment.

2. Under some circumstances such observers are dichromats. There is a neutral point (matched to Illuminant ‘C’) in the neighbourhood of 460–470 nm.

3. The spectral colour matching functions using two primaries have been measured on three such subjects. They can be fit reasonably well, although imperfectly, by linear combinations of π0 and π1. The chromaticity co‐ordinates have been calculated according to the convention of W. D. Wright and compared to the results predicted from π0 and π1. The comparison suggests that part of the imperfections of the colour matching function fit is due to prereceptor differences (e.g. macular pigment) between the blue‐cone monochromats and the hypothetical π0, π1 observer.

4. Colour matches made at high light levels continue to hold when the intensity of the field is reduced below the cone threshold.

5. Therefore one of the visual pigments participating in the colour matches has an action spectrum which is not measurably different from that of the rod pigment rhodopsin.

6. Increment threshold measurements show that the mechanism which has the rhodopsin action spectrum has the directional sensitivity of cones, not rods.

7. Blue test threshold during dark adaptation after a full bleach follow a bipartite exponential recovery curve. The first exponential has a time constant of 1 min, the second 2 min. By comparing these curves to the increment thresholds it is possible to relate the first to the π1, the second to the π0 cones.

8. Using a broad band blue gelatin filter in the measuring light of the retinal densitometer and studying the same retinal region tested in 7 it is possible to follow the regeneration of a pigment after a full bleach which has an exponential recovery with a time constant of 1·0 min. With a yellow green filter in the measuring light the exponential recovery observed after a full bleach has a time constant of 2·0 min.

9. One of the two visual pigments participating in the colour matches resides in receptors which have the action spectrum, the directional sensitivity and probably the dark adaptation curve of normal blue cones.

10. The other resides in receptors which have the action spectrum of normal rods but the directional sensitivity and the dark adaptation curve of normal red and green cones.
Tetanic and post‐tetanic rise in frequency of miniature end‐plate potentials in low‐calcium solutions
Authors: Miledi R. , Thies R.
Published: December 2014

1. Miniature end‐plate potentials (min.e.p.p.s) were recorded intracellularly from frog neuromuscular junctions.

2. The ‘phasic’ release of transmitter which is directly related to nerve impulses was suppressed by withdrawal of Ca from the external medium plus addition of Mg.

3. Under these conditions, min.e.p.p.s continued to be discharged even when EGTA was added, although in this case min.e.p.p. frequency appeared to decrease to about half the rate in normal Ringer.

4. Tetanic stimulation of the nerve approximately doubled the rate of min.e.p.p.s even in Ca‐free solutions with EGTA added.

5. The tetanic increase in frequency was greater without EGTA and greater still with some Ca added. Therefore, it is concluded that the tetanic rise in min.e.p.p. frequency can occur even in the absence of the immediate ‘phasic’ release of transmitter normally induced by nerve impulses; and that the magnitude of the increase is related to Ca concentration.

A possible relation between ‘phasic’ and ‘residual’ effects of nerve impulses is described.
Properties of ‘two‐tone inhibition’ in primary auditory neurones
Authors: Arthur R. M. , Pfeiffer R. R. , Suga N.
Published: December 2014

1. Properties of two‐tone inhibition in primary auditory neurones of cats were studied with phase‐locked sound stimuli. One sound was a continuous tone at the best frequency of a given neurone, and the other, a tone burst which was changed in amplitude, frequency, and phase relative to the continuous tone.

2. The tone burst which caused two‐tone inhibition had either an excitatory or no effect when it was delivered alone. Inhibitory areas commonly appeared on both sides of the excitatory area when the best frequency was higher than a few kc/s.

3. Two‐tone inhibition began and ceased within a few milliseconds of the onset and termination of the excitation caused by a tone burst. The degree of inhibition was greatest at the beginning of the tone burst and reached a plateau within 500 msec. The discharge rate during inhibition could be lower than the rate for either tone alone or for spontaneous activity. At the termination of inhibition, prominent rebound in the discharge rate was found.

4. With an increase in amplitude of a tone burst, for either a fixed or equally increased continuous tone, the discharge rate during inhibition decreased to a minimum and then began to increase. That is, the degree of inhibition was non‐monotonically related to the sound level.

5. Compound period histograms of discharges during inhibition showed that single neurones usually carried information about the combined wave form of the two tones. The information about each tone was, however, modified by the inhibitory phenomenon in both amplitude and phase from that indicated by the compound period histograms for the individual tones.

6. Possible mechanisms and functional significance of two‐tone inhibition are discussed.
Inward and delayed outward membrane currents in isolated neural somata under voltage clamp
Authors: Connor J. A. , Stevens C. F.
Published: December 2014

1. Membrane current—voltage relationships were investigated under voltage clamp conditions in isolated neural somata of marine gastropods.

2. Step depolarizations from the resting potential produce an initial inward current followed by a delayed outward current.

3. Inward current appears to be carried by both sodium and calcium ions and displays time and voltage dependent properties similar to those of other excitable membranes.

4. Activation and deactivation of the delayed outward current follow a more complicated time course than that of a single exponential raised to a power but can be fitted by the product of two exponential functions.

5. Delayed outward current inactivation proceeds with a time constant which decreases as membrane voltage is made more positive. The steady‐state levels of inactivation as a function of membrane voltage are related by an S‐shaped curve similar to that for K inactivation in squid giant axon.
Pulmonary vasodilator and vasoconstrictor actions of carbon dioxide
Authors: Barer Gwenda R. , Shaw J. W.
Published: December 2014

1. Three preparations were used to study the actions of CO2 on the pulmonary vasculature: isolated rat and cat lungs perfused at a constant flow rate with homologous blood and a lobe of cat lung perfused at a constant flow rate in vivo. In all three changes in pulmonary artery pressure (PPa) reflected changes in pulmonary vascular resistance.

2. In the isolated rat lung CO2 caused vasodilatation when vascular tone was high. The lung was first ventilated with N2 causing a rise in PPa. CO2 caused vasodilatation during hypoxia whether the initial blood CO2 level was low or normal and in spite of a fall in blood pH which usually augments the constrictor action of N2.

3. In the rat lung ventilation with CO2 from the control state usually caused weak vasoconstriction. Reducing blood pH with acids also caused weak vasoconstriction while alkali caused vasodilatation.

4. The over‐all effect of CO2 on the pulmonary vasculature depends on a balance between a vasoconstrictor action probably caused by carbonic acid and vasodilatation caused by some other property of the molecule. The dilator action is powerful in the isolated rat lung.

5. By contrast, in both cat lung preparations, no direct evidence for a vasodilator action of CO2 was obtained. Ventilation with CO2 when vascular tone was raised by hypoxia, drugs or acids caused further vasoconstriction. From the control state CO2 caused strong vasoconstriction.

6. Indirect evidence from other work suggests that a pulmonary vasodilator action of CO2 exists in the cat but is usually masked by the strong vasoconstrictor action of carbonic acid. In life the dilator mechanism may be important when pH changes caused by CO2 are minimized by renal compensation.
Contractile and electrical responses of vagus‐innervated frog sartorius muscles
Authors: Landmesser Lynn
Published: December 2014

1. Frog sartorius muscles were transplanted to the thoracic region and re‐innervated by the gastric vagus nerve. Contractile responses of the re‐innervated muscles were studied. Micro‐electrodes were used to measure electrical properties of the muscle fibre membrane. Histological studies of the sartorius and vagus nerves and re‐innervated muscles were also carried out.

2. Autonomic nerve fibres of the gastric vagus form functional connexions with the skeletal muscle fibres. Such vagus‐innervated muscle fibres do not atrophy.

3. Neither the contractile nor the passive electrical properties of the muscle fibres are altered by vagal innervation.

4. Synaptic transmission is quantal in nature and describable by a Poisson distribution as at normal sartorius junctions. The muscle fibres, however, do show extensive multiple‐innervation, and unlike normal sartorius junctions, vagus‐muscle junctions have a low quantal content and show a long‐lasting facilitation.

5. Properties of the vagus nerve fibres apparently are not altered by synapsing with skeletal muscle fibres. They remain small diameter and have high threshold for electrical stimulation.

6. The ability of these nerve and muscle fibres to influence each other is rather limited in the adult amphibian.
The contribution of the adrenal gland to the total amount of progesterone produced in the female rat
Authors: Fajer A. B. , Holzbauer Margarethe , Newport Helen M.
Published: December 2014

1. The amount of progesterone contained in both adrenal glands of a rat was similar to or larger than the amount of progesterone in the ovaries of the same rat. This was found in unstressed rats, in stressed rats and also in pregnant rats.

2. After ether anaesthesia and exsanguination the adrenal progesterone content was increased by 75%; the ovarian progesterone content remained unchanged.

3. In contrast, prolonged operative stress resulted in a rise in the ovarian content of progesterone and 20‐dihydroprogesterone whereas the adrenal progesterone content of these rats was lower than that of unstressed rats.

4. The rate at which progesterone was secreted by the adrenal glands of stressed rats was similar to the ovarian progesterone secretion rate. Rats which were kept under mild stress conditions before the experiment showed higher adrenal progesterone secretion rates.
Recurrent inhibition of interneurones monosynaptically activated from group Ia afferents
Authors: Hultborn H. , Jankowska Elẓbieta , Lindström S.
Published: December 2014

1. Interneurones monosynaptically excited from large muscle spindle (Ia) afferents and inhibited from motor axon collaterals were searched for in the lumbar spinal cord of the cat.

2. Monosynaptic Ia excitation was found in sixty‐seven of sixty‐nine interneurones inhibited by antidromic volleys. These interneurones were excited from Ia afferents from one or a few muscles (mainly close synergists). Volleys in high threshold muscle and skin afferents (FRA) evoked polysynaptic excitation or inhibition. Weak inhibition from Ia afferents (from antagonists to those giving Ia excitation) was seen in a few cells. Monosynaptic excitation was evoked from the ventral quadrant of the spinal cord and polysynaptic excitation from the dorsal quadrant.

3. Inhibition from motor axon collaterals was evoked with a latency (1·2–2·0 msec) suggesting a disynaptic linkage and had the same time course as in motoneurones. It prevented synaptic activation of 60% of interneurones and decreased the firing index and delayed generation of spikes in the remaining.

4. The interneurones with convergence of monosynaptic Ia excitation and inhibition from motor axon collaterals were found in the ventral horn dorsomedial to motor nuclei. No inhibition by antidromic volleys could be detected in interneurones located in intermediate nucleus and activated monosynaptically from Ia, Ib, group I or cutaneous afferents.

5. It was concluded that the ventral Ia interneurones inhibited by volleys in recurrent motor axon collaterals mediate the reciprocal Ia inhibition to motoneurones.
Intestinal transfer of choline in rat and hamster
Authors: Sanford P. A. , Smyth D. H.
Published: December 2014

1. The transfer of choline was studied with sacs of everted intestine of rat and hamster.

2. The choline transfer can be divided into two components, a diffusion process and a saturable process. The latter plays a relatively greater part at low concentrations of choline, which include the physiological concentration in the plasma. The saturable process is better seen in the hamster than in the rat.

3. Intestinal transfer of choline is influenced by substances altering the availability of energy in the cell, and by some substances chemically or pharmacologically related to choline. These findings are consistent with some kind of specific mechanism for choline transfer.

4. Part of the choline taken up by the cell appears as a metabolite not yet identified. The formation of the metabolite is a saturable process and is abolished by anaerobic conditions and by homogenization.

5. The results are also discussed in relation to parameters of transfer.
Configuration dependence of scotopic spatial summation
Authors: Sakitt B.
Published: December 2014

1. Psychophysical experiments were done under conditions of complete dark adaptation, 7° in the human temporal retina, using blue‐green flashes brief enough to be within the range of complete temporal summation.

2. Frequency‐of‐seeing experiments were done for two 3·4′ squares separated by 20′ or 23′ and for each square separately. The results were consistent with the hypothesis that the squares acted independently in determining the absolute threshold. There was no observable summation occurring between them.

3. The absolute threshold (50% seeing) for two 3·4′ squares (the centre‐to‐centre separation varied from 3·4′ to 56′) was measured relative to the absolute threshold for just one such square. It required more photons at the cornea at threshold for two spots than for one such spot, except when they were actually touching.

4. The same subject, in the same retinal region and under otherwise identical test conditions, showed complete spatial summation at absolute threshold for circular spots up to 30′ in diameter.

5. Similar experiments were done on other subjects using 3·4′ squares and lines of width 3·4′. All subjects showed complete summation at absolute threshold for lines 34′ long. All showed lack of spatial summation for two squares unless the two squares touched to form a rectangle.

6. The absolute threshold for N small spots was compared to the absolute threshold for 1 spot, where N varied from 2 to 25. Again complete spatial summation broke down even when all the spots lay within the Ricco area.

7. It was shown that the results are inconsistent with the hypothesis of a linear output and a linear summation of excitations.

8. Various hypotheses are examined and it is shown that no simple hypothesis can explain all the results. The conclusion is that spatial summation at absolute threshold is configuration dependent.
Intracellular concentrations of sodium, potassium and chloride in the lactating mammary gland and their relation to the secretory mechanism
Authors: Linzell J. L. , Peaker M.
Published: December 2014

1. The intracellular (
I.C.) concentrations of Na, K and Cl in mammary cells from lactating guinea‐pigs have been calculated from the analysis of fresh tissue and the measurement of the extracellular (
E.C.) space with [14C]sucrose and the milk content with [14C]lactose.

2. Assuming that alveolar milk has the same concentration as teat milk, the intracellular concentrations were calculated to be K 115, Na 42 and Cl 66 m‐equiv. l−1 intracellular water.

3. Intracellular concentrations were also calculated in slices incubated in Krebs—bicarbonate medium plus glucose. There was a large increase in the sucrose (
E.C.) space and a rise in total tissue [Na] and [Cl]. On the assumption that the medium had equilibrated with the milk space as well as the
E.C. space, the calculated
I.C. concentrations of Na (43 m‐equiv. l−1), and Cl (62) were very similar while [K] was somewhat higher (143 m‐equiv. l−1
I.C. water).

4. The calculated
I.C. concentrations of all three ions are all higher than in milk but the ratios between them are almost identical.

5. Similar figures for the
I.C. concentrations of Na, K and Cl have been obtained in the goat, cow and sheep mammary tissue incubated in vitro.

6. Moderate changes in the concentrations of Na, K and Cl in the external medium had no effect on cell composition but during incubation without ions [14C]sucrose became distributed throughout the total tissue water indicating that sucrose had entered the
I.C. compartment.

7. Acetazolamide (10−2
M), aldosterone (1·4 × 10−6
M) and, in some experiments, lack of glucose lowered
I.C. [Cl−], but oxytocin, vasopressin and low doses of insulin had no effect.

8. The data are difficult to reconcile with the hypothesis of Zaks, Natochin, Sokolova, Tanasiichuk & Tverskoi (1965) that freshly secreted milk has the ionic composition of plasma.

9. Comparison of
I.C. ion concentrations and the membrane potential between the cells and milk suggests that Na+ and K+ are passively distributed across the apical membrane but that Cl− must be actively held in the cells. Across the basal membrane the data are consistent with the presence of a Na+ pump and with Kinura's (1969) detection of a Na:K ATPase on the basal and lateral membranes. In addition another inward‐facing Cl− pump may exist at this site.
Salt and water permeability of the epithelium of the coprodeum and large intestine in the normal and dehydrated fowl (Gallus domesticus). In vivo perfusion studies
Authors: Bindslev Niels , Skadhauge Erik
Published: December 2014

1. The transmural net flow of salt and water in the coprodeum and large intestine of normal and dehydrated hens was investigated by means of an intraluminal in vivo perfusion technique.

2. The lumen was perfused with a raffinose‐electrolyte solution having a low sodium concentration (Na+ = 1 m‐equiv/l.). The osmolality of the solution was adjusted in the range 66–585 m‐osmolal by adding raffinose. Polyethylene glycol 4000 (PEG) served as a water marker. The experiments permitted estimation of the passive transport parameters: the reflexion coefficient (σ) of the penetrating solutes (predominantly NaCl), the Na+ mobility (ωs), and the osmotic water permeability coefficient (Posm).

3. When the luminal fluid had the same osmolality as plasma the net water flow (Jv) was zero, indicating a σ of unity. The net flow of Na+ was zero, (at Jv = 0) and a transmural electric potential difference close to zero was present both in normal and in dehydrated birds. This indicates an ωs of zero. When lumen osmolality was higher than that of plasma, no ‘solvent drag’ effect on Na+ was demonstrated in the serosa to mucosa (s—m) direction.

4. The Posm appeared to be independent of the luminal osmolality in the range of ±200 m‐osmolal from plasma osmolality. In normal birds the Posms—m was 3·2 μl./kg.hr.m‐osmolal, the Posmm—s 5·8 μl./kg.hr.m‐osmolal. In dehydrated birds these values were 3·6 and 10·0 respectively. Thus there seems to be rectification of water flow, and it varies with the state of hydration.

5. A net K+ flow of 15–50 μ‐equiv/kg.hr in the m—s direction and a net Clμ flow of 10–50 μ‐equiv/kg.hr in the s—m direction were observed. No relationship was observed between the flow of these solutes and the net water flow.
Impairment of glycine absorption by glucose and galactose in man
Authors: Cook G. C.
Published: December 2014

1. In order to investigate a possible competition for intestinal transport between amino acids and monosaccharides in man, iso‐osmotic solutions containing (A) 100 m‐mole glycine 1.−1, (B) 100 m‐mole glycine and 200 m‐mole monosaccharide (glucose or galactose) 1.−1, and (C) 200 m‐mole monosaccharide 1.−1, were successively perfused into the upper jejunum of twelve African Zambian patients. None had clinical evidence of malnutrition or small‐intestinal disease. By using a double‐lumen tube and by reference to a non‐absorbable marker (polyethylene glycol, 4000), the rates of absorption of these substances have been calculated for a 30 cm jejunal segment.

2. The presence of glucose and galactose produced a significant impairment (up to 50%) in the rate of absorption of glycine. There was also a significant decrease in the uptake of both monosaccharides from the solutions in which glycine was also present.

3. If this observation also applies to other amino acids it could have a practical value in population groups living on high carbohydrate diets with a marginal concentration of some essential amino acids. It could have special importance when the jejunal mucosa is damaged in severe malnutrition or gastrointestinal infection. This impairment of amino acid uptake may explain the very high incidence of genetically determined lactase‐deficiency in Africa.
Sustained and transient neurones in the cat's retina and lateral geniculate nucleus
Authors: Cleland B. G. , Dubin M. W. , Levick W. R.
Published: December 2014

1. Cat retinal ganglion cells may be subdivided into sustained and transient response‐types by the application of a battery of simple tests based on responses to standing contrast, fine grating patterns, size and speed of contrasting targets, and on the presence or absence of the periphery effect. The classification is equivalent to the ‘X’/‘Y’ (linear/nonlinear) subdivision of Enroth‐Cugell & Robson which is thus confirmed and extended.

2. The sustained/transient classification applied to both on‐centre and off‐centre cells.

3. Lateral geniculate neurones may be similarly classified by the same tests. Occasional concentrically organized cells had a mixture of sustained and transient properties.

4. A technique for simultaneous recording from a geniculate neurone and one or more retinal ganglion cells providing its excitatory input showed that the connexions were specific with respect to the sustained/transient classification as well as the on‐centre/off‐centre classification. Most geniculate neurones are excitatorily driven only by retinal ganglion cells of the same functional type. In a few cases the inputs were mixed but only with respect to the sustained/transient classification.

5. Sustained retinal ganglion cells had slower‐conducting axons than the transient type. The same was true for lateral geniculate neurones but in this case the distributions showed considerable overlap.

6. The sustained/transient classification is the functional correlate for the well‐known segregation of optic nerve fibres into two conduction groups.

7. The pathways carrying sustained and transient information remain essentially separate from retina through the lateral geniculate nucleus to the striate cortex.
The mechanics of sprint running
Authors: Cavagna Giovanni A. , Komarek L. , Mazzoleni Stefania
Published: December 2014

1. The effect of the velocity of shortening on the power developed by the muscles in sprint running was studied by measuring the mechanical work done to accelerate the body forward from the start to about 34 km/hr.

2. The work was measured at each step from the data obtained by means of a platform sensitive to the force impressed by the foot.

3. Almost the totality of the positive work done during the first second from the start is found as an increase of the kinetic energy of the body. However, as the speed of the run rises, air resistance and particularly the deceleration of the body forward, taking place at each step, rapidly increase, limiting the speed of the run.

4. The average power developed by the muscles during the push at each step increases with the velocity of running reaching 3‐4 h.p. at the maximal speed attained.

5. At low speed the contractile component of the muscles seems to be mainly responsible for the power output, whereas at high speed (25–34 km/hr) an appreciable fraction of the power appears to be sustained by the mechanical energy stored in the ‘series elastic elements’ during stretching the contracted muscles (negative work) and released immediately after in the positive work phase.
Noradrenaline and acetylcholine responses of supraoptic neurosecretory cells
Authors: Barker J. L. , Crayton J. W. , Nicoll R. A.
Published: December 2014

1. Neurones in the supraoptic nucleus were examined for their responsiveness to microiontophoretically applied monoamines and cholinomimetic agents. One hundred and sixty‐one of the 749 neurones recorded were antidromically identified as neurosecretory cells.

2. The monoamines, dopamine, noradrenaline and serotonin, reduced the activity of all cells which responded.

3. Reduction in activity following noradrenaline administration was antagonized by the β‐adrenergic blocking agent MJ‐1999 and potentiated by desmethylimipramine.

4. Acetylcholine produced either a decrease or an increase in activity of responsive cells with depression the predominant result. Both the depressant and the excitatory response to acetylcholine were seen in individual neurosecretory cells which were depressed by noradrenaline.

5. Application of acetyl‐β‐methylcholine and carbaminoylcholine consistently resulted in depression of all responsive cells, while nicotine excited the majority of responsive cells. Both types of response were observed on the same neurosecretory cell.

6. The depressant response was antagonized by the muscarinic blocking agent atropine while the excitatory response was antagonized by the nicotinic blocking agent dihydro‐β‐erythroidine. Responses to acetylcholine were potentiated by the acetylcholinesterase inhibitor physostigmine.

7. The data indicate that noradrenaline‐containing terminals on these neurosecretory cells are likely to inhibit their discharge rate, while the presumed cholinergic terminals might function as either excitatory or inhibitory, depending on the receptor activated.

8. These results support the hypothesis that ADH release is related to the neuronal activity of the supraoptic neurosecretory cell.
Changes of sodium and urea concentrations in the renal papillary interstitial fluid on dehydration of rats
Authors: Lee J. , Williams P. G.
Published: December 2014

1. The isolated renal papillae of a rat were centrifuged in a two tube assembly which allowed fluid from the tissue to separate into the lower tube.

2. The papillae were centrifuged for 15 min at 300 g and 1500 g consecutively.

3. After intraperitoneal injection of Na 131I‐diatrizoate, the activities of urine, and fluid samples obtained from the papilla, were compared. It was found at 1500 g that the median value for papillary fluid activity was 1·52% of the activity of urine. This is evidence that the papillary fluid was virtually free from any contamination from the terminal collecting ducts.

4. It is considered that the fluid sample obtained from the papillae by centrifugation at 1500 g is a representative and reproducible sample of interstitial fluid.

5. The method was used to demonstrate changes in solute concentrations in the renal papillary fluid, following dehydration of rats.
Effects of descending impulses on transmission through the spinocervical tract
Authors: Brown A. G.
Published: December 2014

1. Micro‐electrode recordings were made from ascending axons of the spinocervical tract in unanaesthetized decerebrate cats before, during and after reversible cold block of impulse conduction in the spinal cord rostral to the recording site.

2. Most units (forty‐one of forty‐four) fell into one of four categories as defined by their evoked responses to mechanical stimulation of identified cutaneous receptors. These categories were; Type I excited by movement of tylotrichs (hairs) in the decerebrate preparation but by movement of all types of hairs after block of descending impulses; Type II excited by movement of guard hairs and usually weakly by pressure in the decerebrate state but by movement of all types of hairs and by pressure in the spinal state; Type III excited by movement of all types of hairs and often by pressure in the decerebrate animal but by movement of all types of hairs and always by pressure in the spinal animal; Type IV weakly excited by heavy pressure or with no receptive field in the decerebrate state but excited by pressure in the spinal state.

3. The descending influences depressed the spontaneous activity and the evoked responses to harmful stimuli.

4. The descending influences depressed inhibitory inputs from segmental levels.

5. The functional significance of the descending control is discussed.
The effect of intravenous infusion of antidiuretic hormone on water intake in the rat
Authors: Rolls Barbara J.
Published: December 2014

1. In rats the continuous
I.V. infusion of ADH at rates up to 6·0 mu. kg−1 min−1 decreased drinking caused by water deprivation, by a 10% increase in osmotic pressure, and by caval ligation.

2. Infusion of ADH at rates between 0·07 and 6·0 mu. kg−1 min−1 never potentiated drinking nor did it significantly affect the 24 hr water intake of rats that were in water balance at the start of the experiment.

3. Urine output was slowed by a rate of infusion (13·0 μu. kg−1 min−1) which was approximately 150 times smaller than the lowest rate which was found to decrease water intake.

4. Since the rates of infusion of ADH which directly affect water intake and urine flow are so different, it is unlikely that ADH is a general homoeostatic hormone which controls both thirst and urine output in the rat.
The secretory nerves of the parotid gland of the dog
Authors: Holmberg Jan
Published: December 2014

1. Secretory nerve fibres to the parotid gland of the dog have been found in the adventitia of the internal maxillary artery. In dogs under chloralose anaesthesia the course of these fibres from the mandibular nerve to the gland was determined by electrical stimulation at different sites. Secretion induced by these nerves was abolished by atropine but not by hexamethonium.

2. In dogs in light barbiturate anaesthesia parotid secretion was evoked reflexly by pouring citric acid on the tongues. After division of the auriculo‐temporal nerve and the nerves on the artery this secretion disappeared in about half the experiments and was greatly reduced in the others.

3. The maximal secretory rate which could be obtained reflexly from the normally innervated parotid gland was first estimated in light barbiturate anaesthesia. Chloralose was then given and the auriculo‐temporal nerve and the nerves on the artery were electrically stimulated together; in about half the experiments this could produce secretion at a rate as high as that obtained reflexly.

4. By separate and simultaneous stimulation of different sets of nerve fibres convergence of the secretory fibres to the glandular cells could be demonstrated.

5. It is concluded that a large number of post‐ganglionic, cholinergic secretory fibres to the canine parotid gland run on the internal maxillary artery. In some dogs a small number of fibres seem to have escaped detection. Possibly they may reach the gland by way of the facial nerve.
The locations and activities of medullary neurones associated with ruminant forestomach motility
Authors: Harding R. , Leek B. F.
Published: December 2014

1. Neuronal activity bearing a temporal relationship with spontaneous reticulo‐ruminal movements was recorded with micro‐electrodes from the medulla oblongata in halothane‐anaesthetized sheep. Recording sites were located histologically after causing electro‐coagulation at the micro‐electrode tip.

2. One hundred and forty‐four gastric units were recorded from the dorsal vagal nucleus and up to 1 mm dorsal and lateral to the nucleus between transverse planes 1 mm caudal, and 4 mm rostral, to the obex. It is considered that records were obtained from the regions of cell bodies.

3. The discharges of thirty‐two vagal preganglionic motoneurones were identified by an antidromic collision technique. Conduction velocities ranged from 10–26 m/sec. They were located in the dorsal vagal nucleus and up to 0·5 mm dorsal and lateral to the nucleus. The majority of motoneurones innervated either the reticulum or the rumen. One ruminal unit discharged during both primary and secondary cycle movements.

4. One hundred and twelve units which were not orthodromically or antidromically activated by stimulating the vagus nerves were considered to be interneurones. Four types were distinguishable on the basis of their patterns of discharge during primary cycle movements.

5. The discharges of Type A interneurones resembled those of gastric motoneurones, having no resting discharge between contraction cycles. Their discharges were temporally related to either reticular contractions or rumen contractions during primary and secondary cycle movements.

6. Types B and C interneurones have resting discharges which, respectively, increased and either decreased or stopped during each primary cycle movement.

7. Discharges of only three units identified as interneurones resembled the discharges of gastric vagal afferent units.
Respiratory movements and rapid eye movement sleep in the foetal lamb
Authors: Dawes G. S. , Fox H. E. , Leduc B. M. , Liggins G. C. , Richards R. T.
Published: December 2014

1. In foetal lambs from 40 days gestation (0·27 of term) onwards delivered into a warm saline bath, apparently spontaneous breathing movements were present intermittently. They became deeper and more rapid with increasing age.

2. In foetal lambs (from 0·66 of term) in which observations were made for many days after chronic implantation of tracheal, carotid and amniotic catheters, rapid irregular respiratory movements were present up to 40% of the time, and brief gasps also were seen.

3. The presence of these movements was unrelated to the foetal carotid blood gas values over a wide range of spontaneous variation.

4. These foetal breathing movements were accompanied by comparatively small alterations of pulmonary volume recorded from a tracheal flowmeter, insufficient to clear the tracheal dead space. Occasionally a more prolonged expiration led to the outward flow of fluid.

5. A description is given of sleep and wakefulness in foetal lambs from 0·78 of term.

6. Rapid irregular breathing was associated with rapid eye movement sleep as seen in a warm saline bath or, in utero, as inferred from records of eye movements and electrocortical activity.

7. Respiratory movements were often associated with relatively large variations in foetal heart rate, blood pressure and descending aortic blood flow.

8. Rapid irregular foetal breathing was unaffected by section or blockade of the cervical vagi, but was abolished by general anaesthesia.

9. It is concluded that respiratory movements are normally but intermittently present in the foetal lamb over the greater part of gestation.
Sympathetic inhibition of the urinary bladder and of pelvic ganglionic transmission in the cat
Authors: de Groat William C. , Saum William R.
Published: December 2014

1. Electrophysiological techniques were utilized to study the mechanisms underlying adrenergic inhibition in the urinary bladder of the cat.

2. It has been shown that catecholamines administered by close intraarterial injection or released endogenously by electrical stimulation of the hypogastric nerves elicit two distinct inhibitory responses in the bladder: (1) a direct depression of the vesical smooth muscle and (2) a depression of transmission in vesical parasympathetic ganglia.

3. Pharmacological studies revealed that the inhibitory mechanisms were mediated via different adrenergic receptors: β‐receptors on the smooth muscle and α‐receptors in the parasympathetic ganglia.

4. We have been unable, however, to demonstrate that either of these mechanisms is activated by naturally occurring sympathetic firing.
Radio‐immunoassay of gastrin in human plasma
Authors: Ganguli P. C. , Hunter W. M.
Published: December 2014

1. A radio‐immunoassay for gastrin has been developed using partially purified porcine gastrin to raise antibodies and highly purified natural porcine gastrin I for radio‐iodination with 125I. The separation of antibody‐bound from free hormone was performed by a double‐antibody method.

2. In this assay highly purified natural porcine gastrin I, synthetic human gastrin I, radio‐iodinated porcine gastrin I, gastrin in the plasma of a healthy volunteer, a patient with pernicious anaemia and another patient with the Zollinger—Ellison syndrome were immunologically identical.

3. The fasting plasma gastrin concentration of fourteen gastric ulcer patients was significantly higher than that of the 113 hospital controls with no history of gastro‐intestinal disease, while twenty‐seven duodenal ulcer patients had gastrin levels within the normal range.

4. Plasma gastrin concentration was significantly elevated in pernicious anaemia (fifty‐one patients), achlorhydria (thirty‐three patients), hypochlorhydria (eleven patients) and in nine patients with histologically proven Zollinger‐Ellison syndrome.

5. In human volunteers a protein meal stimulated endogenous gastrin release while a carbohydrate meal did not. Atropine sulphate
I.M., and hydrochloric acid orally, produced a significant fall in the level of circulating gastrin.
The metabolic basis to the fluid pump in the cornea
Authors: Dikstein S. , Maurice D. M.
Published: December 2014

1. A technique for isolating and perfusing the rabbit cornea is described, which allowed its thickness to be continuously measured under the microscope. The reversal of thickness of the cold‐swollen cornea on perfusion with various solutions at 37° C was studied.

2. It was found that only a combination of adenosine and glutathione was able to reliably reverse the thickness to its normal value. This mechanism is sodium, bicarbonate, and oxygen dependent. Inhibitors of glycolysis or electron transport stop the reversal process.

3. The findings are consistent with a need for an ATPase but are not capable of distinguishing among several possibilities for its regulation.
Characteristics of spinal neurones responding to cutaneous myelinated and unmyelinated fibres*
Authors: Gregor M. , Zimmermann M.
Published: December 2014

1. Spike discharges were recorded from neurones in the lumbar spinal cord in cats anaesthetized by barbiturate.

2. The neurones were examined systematically for various physiological parameters and for their location. Especially the neurones situated in the dorsal horn were classified for the following parameters: mono‐ or polysynaptic linkage to myelinated afferents; type of natural stimuli which excited the neurones; depth from the cord surface; number of impulses discharged upon a cutaneous A fibre stimulus; steady‐state discharge in the absence of intentional stimulation.

3. All neurones were also tested as to whether or not they responded to volleys in cutaneous C fibres. Of 111 units which were activated by the A fibres in nerves from the hairy skin, 57 (= 51%) responded to C volleys in those nerves too.

4. By blocking conduction in the A fibres using polarizing currents it was shown that the responses to C fibre volleys were partially or totally suppressed by a preceding discharge of the neurone in response to an A volley. Using search stimuli which were suprathreshold for C fibres one cell out of 36 could be found which responded only to afferent volleys in C fibres.

5. About half of all neurones were shown to be connected monosynaptically to cutaneous A fibres, as was judged from the synaptic delay. The other half were polysynaptically linked to the A fibres. Both mono‐ and polysynaptic neurones were found in all layers of the dorsal horn. About 15% of the cells had additional input from muscle Group II and/or III fibres via polysynaptic pathways.

6. Subdividing the A and A+C responsive neurones according to their mono‐ (M) or polysynaptic (P) connexions yielded the following sub‐samples: MC, 39%; PC, 15%; MA, 13%; PA, 33%. Most MC neurones had, and most PA units had not, a spontaneous discharge. About half of the PA cells could not be driven by natural skin stimulation. The majority of MC units responded specifically to movement of hairs.

7. A model was proposed hypothesizing two pathways in the dorsal horn, one showing convergence of A and C fibres and the other not. Some relations concerning other observations on C fibre effects were discussed.
Reversible differential block of saphenous nerve by cold
Authors: Byck R. , Goldfarb J. , Schaumburg H. H. , Sharpless S. K.
Published: December 2014

1. This report is concerned with the question of whether the alpha and delta groups of myelinated A fibres show conduction failure at different temperatures.

2. The experiments were done on cat saphenous nerve in vitro. Stimuli were applied to both ends of the nerve and biphasic recordings were taken adjacent to an 11 mm segment of nerve, whose temperature was varied. Before cooling commenced, the stimuli were adjusted so that the action potential which passed through the cold zone and was recorded, collided with the action potential initiated at the opposite end of the nerve.

3. Upon cooling the nerve, it was always observed that the delta peak of the action potential which had been previously occluded by collision reappeared at a temperature at which the alpha peak remained occluded.

4. The reappearance of the delta peak was reversible upon warming the nerve and was not affected by increasing the interstimulus interval.

5. The mean temperature for reappearance of the delta peak was 13·5° C, for reappearance of the alpha peak, 5·3° C.

6. In any given nerve, the blocking temperature was replicable and was dependent on the temperature of the cooled segment rather than the gradient between that segment and the remainder of the nerve.

7. We conclude that in cat saphenous nerve, the delta group of myelinated A fibres shows conduction failure at a higher temperature than does the alpha group.
The visibility and fading of thin lines visualized by their controlled movement across the retina
Authors: Sharpe C. R.
Published: December 2014

1. The entoptic shadows of the retinal blood vessels were visualized by temporal modulation of their contrast.

2. For perception of fine detail, the shadows must move successively from one photoreceptor to the next. To see coarser detail the contrast need only be temporally modulated.

3. The contrast threshold of the pattern of shadows rises steadily as they are viewed until the shadows can no longer be seen even with the highest contrast available.

4. This elevation of contrast threshold is partially binocularly transferred, suggesting that the perceptual fading has a central origin.

5. The fading of the shadows is specific for their orientation, direction of movement and their width.

6. Image movements like those produced by fixational eye movements have been simulated. The shadows still fade; the results can be explained in terms of spatial adaptation (Blakemore & Campbell, 1969) of spatial frequency and orientation channels.
Localization of intra‐abdominal thermoreceptors in the ewe
Authors: Rawson R. O. , Quick K. P.
Published: December 2014

1. In neutral environmental temperatures, shivering was induced in sheep by intra‐ruminal cooling. Shivering was then depressed for a period by intra‐abdominal heating. Intra‐abdominal heating without ruminal cooling induced panting and a reduction of caval temperatures. Posterior caval temperatures were found to be inappropriate to the responses observed.

2. Intra‐abdominal heating of sheep in cold and warm environments depressed shivering and augmented panting respectively. Unilateral splanchnotomy abolished these responses on the ipsilateral side.

3. The results are interpreted to indicate that the thermoreceptors stimulated lie within the walls of the rumen and intestine, and possibly the mesenteric veins.

4. The splanchnic nerves are indicated as the afferent pathway for these receptors, and differential splanchnic innervation of the gut is suggested to explain unilateral abolition of the response to warming.
Psychophysical estimates of visual pigment densities in red‐green dichromats
Authors: Miller S. S.
Published: December 2014

1. The spectral sensitivity of red‐green dichromats was determined using heterochromatic flicker photometric matches (25–30 c/s) on the fovea. These matches are upset after a bright bleach and consequently the spectral sensitivity is altered.

2. Preliminary experiments indicate that under the conditions in which these experiments were performed, the blue cone mechanism of deuteranopes and protanopes cannot follow 20 c/s flicker. If dichromats lack one of the normal pigments then the upset of these matches monitors the change in spectral sensitivity of a single mechanism.

3. After a bleach which removes all the cone pigments, the spectral sensitivity recovers with the time course of pigment kinetics as measured by densitometry.

4. An intense background also changes the relative spectral sensitivity of the dichromats. On real equilibrium backgrounds, the changes in spectral sensitivity follow those predicted by the pigment changes measured by densitometry. The predicted changes are obtained by modifying the Rushton equilibrium equation to take into account the density of pigment.

5. The relationship of these changes to the luminance of the background is independent of the colour of the background light.

6. In contradistinction the effect is dependent on the colour of the lights which were flickered. These experiments indicate that a narrowing of the spectral sensitivity curves takes place on both sides of the dichromats' λmax.

7. The change in relative spectral sensitivity as a function of background intensity was also determined by increment threshold measurements. These changes can be expressed in terms of deviations from Weber's law (ΔI/I = const.) if ΔI and I represent the number of chromophores destroyed by the test and background.

8. The relative spectral sensitivity of the dichromat was changed by decentering the point of pupil entry. This upset was abolished by bleaching. The size of the upset was correlated with the magnitude of the S—C I effect.

9. Given the hypothesis of pigment density (self‐screening), the results of expts. (3)‐(8) are consistent and allow the calculation of a maximum optical density for those pigments which underlie the dichromats' long‐wave mechanism. For the deuteranope a Dλmax of 0·5–0·6 is calculated and for the protanope a Dλmax of 0·4–0·5 is obtained.
Localization of cation interactions in the smooth muscle of the guinea‐pig taenia coli
Authors: Goodford P. J. , Wolowyk M. W.
Published: December 2014

1. An electron microscopic method has been developed and used to study cation binding sites in smooth muscle.

2. Uranyl cations normally bind to the external surface of the plasma membrane. However, uranyl also binds to the inner surface when it is accessible. Similar binding has been observed in skeletal muscle, nerve and red blood cells.

3. Uranyl binds electrostatically, and the binding can be competitively reversed by other cations. By a quantitative procedure the relative affinities Ca2+ ≃ Mg2+ ≫ K+ > Na+ for the membrane sites have been determined. This sequence is in agreement with previous values determined analytically.

4. The results support a counter‐cation hypothesis for the plasma membrane surfaces of the taenia coli, and may explain features of the electrical activity in smooth muscle.