bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neurones in the somatosensory cortex of the rat responding to scrotal skin temperature changes
Authors: Hellon R. F. , Misra N. K. , Provins K. A. 
Published: December 2014

1. In rats the scrotal temperature was raised or lowered with a water‐perfused thermode while micro‐electrode recordings were made of unit activity in the somatosensory (SI) cortex. The electrodes were inserted in the area where the largest evoked potentials had been found from electrical stimulation of the scrotum.2. Changes in firing rate of cortical neurones were found only in the scrotal temperature range of 32–41° C. Within this range 40% of all the cells tested were excited or suppressed by skin warming. At temperatures above or below this range, activity was not affected. Most of the cells responded just to temperature and only 14% were also excited by touch.3. Raising temperature in the range 33–41° C caused 83% of the thermally responding cells to decrease their firing rate and 17% to increase their rate. Individual neurones showed a sudden and maintained change in their activity for scrotal temperature increases of only 2, 1 or even 0·5° C. Mean firing rates changed several‐fold with these temperature increases and further warming did not change the rate. These step‐like changes in firing rate were found at different points over the whole skin temperature range of 33–41° C but most were between 35 and 39° C.4. For a given neurone the step‐like change in activity occurred once its critical temperature was reached, irrespective of whether this was achieved by a step increase of skin temperature over 1–2 sec, or by a slow ramp increase lasting several minutes.5. The results are very similar to those found in the thalamus (preceding paper), but the proportions of cortical cells which were excited or suppressed on skin warming were the reverse of the proportions seen in the thalamus.
Dorsal root potentials produced by afferent volleys in cutaneous group III fibres*
Authors: Gregor Michael , Zimmermann Manfred 
Published: December 2014

1. Dorsal root potentials (DRP) were recorded in the lumbosacral spinal cord of decerebrated unanaesthetized cats, following afferent volleys restricted to the thin myelinated (Group III) cutaneous afferents of the hind limb. The thick myelinated fibres (Group II) were blocked by a depolarizing current.2. A pure Group III volley produced a DRP of negative polarity, called the III—DRP, signalling a depolarization of the intraspinal terminals of afferent fibres. The longer latency of the III—DRP when compared to that of the DRP after a Group II volley was accounted for quantitatively by the lower conduction velocity of the Group III fibres.3. Special attention was given to the presence of III—DRPs having a predominantly positive polarity thus signalling a presynaptic hyperpolarization. Such ‘positive III—DRPs’ were, however, never observed in this investigation.4. Both after transection of the spinal cord at various levels and after administration of pentobarbitone the III—DRP persisted at normal polarity. The duration of the DRPs was increased by these experimental procedures.5. The implications of these findings are discussed in relation to the prominent role postulated for the Group III fibres in the context of the gate control theory of pain.
Equilibrium of nucleotides in frog sartorius muscle during an isometric tetanus at 20° C
Authors: Canfield P. , Maréchal G. 
Published: December 2014

1. The concentrations of creatine, phosphorylcreatine (PC), ATP, ADP, AMP and IMP have been measured in frog sartorius muscles at 20° C during isometric tetani lasting from 0·5 to 12 sec. Each muscle was tetanized once only for the chosen duration. The muscles were poisoned with iodoacetic acid and nitrogen to prevent oxidative and glycolytic activity.2. The rate of PC splitting decreased exponentially with the duration of the tetanus (α = 0·16 sec−1). Net ATP splitting began after 2 sec, accompanied by an increase in AMP and ADP; inosine monophosphate (IMP) also appeared both earlier and faster than adenosine monophosphate (AMP).3. On the basis of two equilibrium reactions, the Lohmann and myokinase reactions, the concentration of adenosine nucleotides should be a function of the ratio creatine/phosphorylcreatine.4. The agreement between nucleotide concentrations predicted by this equilibrium hypothesis and those observed experimentally was good provided it was assumed that 90% of the acid‐labile ADP found in resting muscle was bound in vivo and remained so throughout the tetanus. The validity of this assumption is discussed.5. The IMP concentration was an exponential function of the ratio creatine/phosphorylcreatine.
Energy balance in frog sartorius muscle during an isometric tetanus at 20° C
Authors: Canfield P. , Lebacq J. , Maréchal G. 
Published: December 2014

1. Changes in the concentrations of ATP, ADP, AMP, IMP, creatine and phosphorylcreatine (PC) have been measured in frog sartorius muscles after different periods of isometric stimulation at 20° C. The heat production was measured in parallel experiments with a thermopile of the Hill‐Downing type.2. Muscles were either in O2 and unpoisoned or in N2 and poisoned with iodoacetic acid to prevent aerobic and glycolytic recovery processes.3. Poisoning did not appear to alter the heat production of these muscles and had little effect on the tension for up to 8 sec tetanus.4. The break‐down of high‐energy phosphates (∼ P) during contraction was faster in the poisoned muscles. Normal muscles were thus able to resynthesize high energy phosphates during the contraction. The resynthesis began at its maximum rate; part of it was probably due to glycolytic activity.5. During the first 2 sec of contraction (poisoned muscles), the only net reaction was an hydrolysis of PC, with an apparent enthalpy change of −8·3 kcal/mole. During longer contractions, the PC hydrolysis was accompanied by a net ATP hydrolysis and appearance of AMP and IMP.6. For the first 2 sec of contraction in the poisoned muscles, the observed heat agreed with that expected from the observed chemical changes multiplied by their molar enthalpy changes. After 2 sec, the observed heat was greater than that expected. At 12 sec this excess was about 74 mcal/g. Possible explanations for this discrepancy are discussed.
Responses of single rods in the retina of the turtle
Authors: Schwartz E. A. 
Published: December 2014

1. The responses of rods in the retina of the turtle, Chelydra serpentina, have been studied by intracellular recording.2. The identification of rods as the origin of the recorded responses has been confirmed by marking with Procion Yellow.3. The response to a small spot of light was a hyperpolarization which increased with increasing light intensity. For dim, small diameter stimuli, the shape of the rod response was similar to that of cones but 2× slower and 2× larger in amplitude. The time integral of the rod response to a dim, small diameter flash is, therefore, approximately 4× greater than the integral of the cone response.4. The shape of the rod response depended on the pattern of retinal illumination as well as stimulus intensity. Enlarging the area of illumination increased the peak amplitude and delayed repolarization following a light step. The area of retina which influenced the response was approximately 200 μm in radius.5. It is concluded that for dim light the responses of rods are larger than those of cones because of (i) a greater response to direct illumination and (ii) an enhancement of response by interaction from a large retinal area.
Foetal bile pigment handling after administration of [14C] haemin
Authors: Jackson Benjamin T. , Lester Roger , Little Joanna M. , Piasecki George J. , Rauschecker Helmut F. J. , Smith Paul M. 
Published: December 2014

1. Advanced techniques for intra‐uterine surgery were used to study haem degradation in foetal sheep prepared in utero with indwelling jugular, carotid and biliary cannulas. [14C]haemin was administered I.V. to the foetus, and plasma disappearance, biliary excretion, placental transfer and tissue distribution of radioactivity were measured over a 5–8 hr period.2. 8–30% of the 14C‐label was recovered in foetal bile, about 40% of this as bilirubin and the rest as unidentified [14C]haemin derivatives. 4–21% was transferred across the placenta, appearing in maternal bile almost exclusively as [14C]bilirubin. Excretion of 14C‐label totalled 18–33%.3. Six adult sheep infused with [14C]haemin excreted 19–49% of the dose in the bile over 8 hr, one third as bilirubin.4. The amount of endogenous bilirubin excreted per unit time/unit wt. of foetal liver increased with increasing foetal wt.5. It is concluded that near‐term foetal sheep have a maturing mechanism for haem catabolism. Haem is partially excreted in foetal bile as bilirubin. Another fraction is transferred across the placenta, probably after prior conversion to bilirubin. The remainder is converted to un‐identifiable end‐products. Total excretion is approximately as effective as that in adults.
The response of malnourished babies to cold
Authors: Brooke O. G. , Harris M. , Salvosa Carmencita B. 
Published: December 2014

1. Twelve malnourished Jamaican children, aged 4–16 months, were studied before and after treatment, to see whether malnutrition impaired their response to cold.2. When they were studied in the post‐absorptive state and in a neutral thermal environment, they had a lower rate of oxygen consumption per kg body weight, a slower pulse rate, lower body temperatures, lower
R.Q., and evidence of a smaller peripheral blood flow on admission to hospital than they did after recovery.3. The malnourished children failed to increase their heat production above resting levels at 25° C, and their rectal temperature fell at a rate of 1° C/hr in spite of a further decrease in peripheral circulation.4. When they had recovered they maintained their body temperature within the normal range on exposure to this temperature, while increasing their heat production by 20%. The thermogenesis was apparently of the non‐shivering type.5. There was evidence of increased metabolic activity in the interscapular brown fat pad at 25° C both on admission and before discharge. In the malnourished children this activity was not sufficient to produce a measurable increase in total oxygen consumption.6. Interscapular brown fat was examined at autopsy in thirteen malnourished and fifteen well nourished children aged 1–24 months. Lipid depletion was found in this tissue in the former but not in the latter. This may explain the impaired response of the malnourished child to cold.
Flux, not retinal illumination, is what cat retinal ganglion cells really care about
Authors: Enroth‐Cugell Christina , Shapley R. M. 
Published: December 2014

1. Evidence was obtained that the impulse/quantum (I/Q) ratio of the central response mechanism of retinal ganglion cells in the cat is controlled by the steady effective retinal flux of the background.2. One experiment revealed that the I/Q ratio was decreased as the area of an adapting spot, of constant illumination, was increased. The curve relating the I/Q ratio to background flux was the same regardless of the size of the adapting spot.3. The effective central summing area of many retinal ganglion cells was determined. For the same cells, the transition level (Enroth‐Cugell & Shapley, 1973) of the impulse/quantum curve was also measured. Diffuse illumination at the transition level was inversely proportional to the effective summing area, when variation in dark‐adapted sensitivity between cells was taken into account.4. Therefore, retinal ganglion cells with large central summing areas are more light‐adapted by any given diffuse background than cells with small centres.
Sodium movements in high‐sodium beef red cells: properties of a ouabain‐insensitive exchange diffusion
Authors: Motais R. 
Published: December 2014

1. The relative importance of the Na efflux components in beef red cells has been evaluated. The component which is insensitive to ouabain, which does not require external K but depends on the presence of external Na, accounts for about 90% of the total Na efflux.2. The experiments reported in this paper are consistent with the presence of an ouabain‐insensitive Na+‐Na+ exchange process accounting for this ouabain‐insensitive external Na dependent efflux.3. A strictly parallel behaviour of influx and efflux is observed when the pH is altered. The exchange diffusion process is inhibited over 90% by a decrease in pH from range pH 8·0‐5·5.4. Both Na efflux and influx are markedly increased by raising the temperature from 27 to 37° C.5. Energy depleted cells and fresh cells behave similarly in respect to Na movements. In depleted resealed ghosts, a large Na‐dependent efflux occurs. No chemical energy and no special nucleotide is required for the Na+‐Na+ exchanges.6. When the external or internal Na concentrations are changed, a parallel behaviour of influx and efflux is observed.7. The relation between the magnitude of the exchange diffusion flux and the external or internal Na concentration fits quite well the Michaelis—Menten equation suggesting that only one Na+ reacts with the transport mechanism. The affinity for Na is lower however at the outer surface than at the inner border of the membrane.8. The relation between this exchange process, the ouabain‐insensitive Na‐Na exchanges found in human red cell, and Ussing's model of exchange diffusion is discussed.
Wave‐length dependencies of light scattering in normal and cold swollen rabbit corneas and their structural implications*
Authors: Farrell R. A. , McCally R. L. , Tatham P. E. R. 
Published: December 2014

1. The studies described herein involve the use of light scattering measurements to characterize the ultrastructural arrangement of the constituent collagen fibrils in rabbit corneal stromas.2. Theoretical light scattering techniques for calculating the scattering to be expected from the structures revealed by electron micrographs are discussed, and comparison with the experimental light scattering tests the validity of these structures.3. The wave‐length dependence of light transmission and of angular light scattering from normal corneas is in agreement with the short range ordering of collagen fibrils depicted in electron micrographs.4. The transmission measurements on oedematous rabbit corneas indicate that transmission decreases linearly with the ratio of thickness to normal thickness.5. The wave‐length dependence of transmission through cold swollen corneas indicates that the increased scattering is caused by large inhomogeneities in the ultrastructure. Electron micrographs do, indeed, reveal the presence of such inhomogeneities in the form of large regions completely devoid of fibrils.
Receptive field analysis: responses to moving visual contours by single lateral geniculate neurones in the cat
Authors: Dreher B. , Sanderson K. J. 
Published: December 2014

1. Responses of single geniculate cells to moving light and dark bars and light/dark edges were studied in cats anaesthetized with nitrous oxide/oxygen (70%/30%).2. Over 95% (230 out of 241) of geniculate cells had antagonistic centre‐surround receptive fields. Their responses could be characterized as centre‐activated or centre‐suppressed depending on the receptive field type (ON‐ or OFF‐centre) and the contrast between stimulus and the background (brighter or darker than the background). Moving light and dark edges evoked responses which were very similar to the responses evoked by these stimuli in simple cells of striate cortex.3. A number of cells (45) with antagonistic centre‐surround receptive fields were classified according to their X/Y (sustained/transient) properties. Units with sustained properties (X‐cells) did not increase their firing rate with an increase of stimulus velocity and some of them showed a clear‐cut preference for slow movement (around 1–2°/sec). On the other hand, units with transient properties (Y‐cells) showed a clear‐cut preference for fast‐moving stimuli (50–100°/sec.)4. Elongation of the stimulus beyond the antagonistic surround in both X‐ and Y‐cells produced a clear‐cut reduction of amplitude of both centre and surround components of the response. Thus the existence of a suppressive field component beyond the antagonistic surround is confirmed.5. About 5% of cells had receptive fields which did not have an antagonistic centre‐surround organization but gave a mixed ON‐OFF discharge from the central region of the field. Around the central region there was a silent suppressive zone. These units were not directionally selective, responded preferentially to fast‐moving stimuli (25–100°/sec) and had a substantial (spontaneous) maintained activity.
Sodium‐dependent transport of sugars and iodide from the cerebral ventricles of the rabbit
Authors: Bradbury M. W. B. , Brøndsted Hans E. 
Published: December 2014

1. The objective was to discover whether the extraction of sugars and iodide from the perfused cerebral ventricles is Na+‐dependent.2. In the ventriculo‐aqueductal and ventriculo‐cisternal perfusion systems in the rabbit the extraction of 14C‐labelled
D‐hexoses (glucose, 3‐O‐methyl‐glucose, α‐methyl‐glucoside and galactose), 131I− and 24Na was inhibited when 82% of the Na+ in the perfusion fluid was replaced by choline. The extraction returned to control levels when the Na+ concentration in the perfusion fluid was returned to normal.3. Ouabain, 5 × 10−5
M in the perfusion fluid inhibited the extraction of the above 14C sugars and 131I−, but hardly affected that of [3H]2‐deoxy‐
D‐glucose. It enhanced the extraction of 24Na. C.s.f. production was usually totally inhibited.4. The extraction of [14C]urea remained unchanged during perfusion with low Na+ fluid or ouabain.5. Recovery from brain of [14C]3‐O‐methyl‐glucose, [3H]2‐deoxy‐glucose and 131I− was low while recovery of [14C]α‐methyl‐glucoside and 24Na was high. On an equal weight basis recovery of [14C]3‐O‐methyl‐glucose was about twelve times higher from the choroid plexus than from the brain.6. Part of the movement of 14C sugars may be explained on basis of a Na+‐gradient hypothesis with involvement of the Na+ pump at the blood—c.s.f. or blood—brain barriers.7. The rate of c.s.f. production from the first three ventricles comprised about 40% of the rate from all four ventricles. The extraction of sugars, urea and cations was similar in both perfusion systems while the extraction of 131I− was higher in the ventriculo‐cisternal system than in the ventriculo‐aqueductal system.
Colour‐dependence of cone responses in the turtle retina
Authors: Fuortes M. G. F. , Schwartz E. A. , Simon E. J. 
Published: December 2014

1. Responses to monochromatic lights were recorded intracellularly from red cones, green cones, and luminosity horizontal cells (L‐cells) in the retinae of turtles.2. Both types of cones responded to small fields of illumination with graded hyperpolarizations. Red cones were only moderately more sensitive to deep red (680 nm) than to green (550 nm) light while green cones were much more sensitive to the green light than to the red. L‐cells produced small responses for flashes of either colour covering small fields.3. Stimulation of large fields with monochromatic lights of moderate or high intensity evoked large L‐cell responses and composite responses in cones. These latter include the hyperpolarizing action of the light absorbed by the cone itself (direct response), its enhancement by illumination of the near surround, and the depolarizing effects of L‐cell feed‐back.4. L‐cells respond primarily to the activity of red cones; with sufficient intensity of the light, however, their responses are influenced also by green cones. As a result, if a red and a green light stimulate red cones equally, the L‐cell response is larger for the green stimulus.5. Green cones were depolarized by deep red lights of moderate intensity applied over large fields. These depolarizing responses include oscillations which follow closely oscillations in L‐cells. Green light applied to the same large fields produced hyperpolarization of green cones.6. Red cones were hyperpolarized by red or green light covering large fields, but the time course of their responses differed for the two colours, reflecting a corresponding difference in L‐cell activity.7. Red light in the form of an annulus produced large responses in central L‐cells without eliciting direct responses in central green cones. In these conditions green cones developed depolarizing waves which included a large, sharp transient.8. It is concluded from these and other results that the direct response of each cone is modified by two interactions: enhancement only from nearby cones of the same colour and depression controlled (through L‐cell feed‐back) by cones of all colours. In this way the response of any cone will change as the proportion of responses in cones of different colours changes, this proportion being a function of the wave‐length of the light.
Membrane potential measurement in parotid acinar cells
Authors: Pedersen G. L. , Petersen O. H. 
Published: December 2014

1. Intracellular recording of membrane potential was made from acinar cells of the isolated mouse parotid gland superfused with physiological salt solutions.2. The mean acinar resting membrane potential was ‐ 68·5 mV during superfusion with Krebs—Henseleit solution. Shift of the superfusion solution to one containing ACh or adrenaline (10−5
M) always caused a transient hyperpolarization (about 10–15 mV).3. The membrane potential was mainly dependent on the extracellular K concentration ([K]o). Increasing [K]o tenfold decreased the membrane potential by 50 mV. This depolarization was not mediated by ACh release from depolarized nerve endings, since it was seen in the presence of atropine (1·4 × 10−6
M) and not caused by the accompanying reduction in [Na]o to 40 m
M caused only a small depolarization (less than 10 mV).4. When the superfusion solution was shifted, during intracellular recording, from a normal Krebs—Henseleit solution ([K] = 4·7 m
M) to a K‐free solution, a hyperpolarization of about 8 mV was measured. Reintroduction of the normal K‐containing solution after a longer period of K deprivation (30–70 min) resulted in a short‐lasting pronounced hyperpolarization (about 20 mV) which could be blocked by Strophanthin‐G (10−3
M).5. In contrast to previous reports, the present findings indicate that the membrane potential of salivary acinar cells is similar, with respect to magnitude and K‐dependence, to that of cells of more thoroughly investigated tissues, such as muscle and nerve, and that the membrane Na—K pump is electrogenic, at least when the cells have been loaded with Na.
Acidaemia produced by spinal stimulation in the pithed rat
Authors: Atkinson Judith M. , Dusting G. J. , Rand M. J. 
Published: December 2014

1. Electrical stimulation of the thoraco‐lumbar spinal nervous outflow in the pithed rat preparation produces a fall in arterial blood pH.2. A component of the acidaemic response results from stimulation of skeletal muscle, since the acidaemic response is reduced when contractions of muscle are blocked with gallamine.3. The residual acidaemic response in gallamine‐treated rats is reduced by adrenalectomy, suggesting that catecholamines liberated from the adrenal medulla may mediate part of the effect.4. Guanethidine reduces the acidaemic response remaining in adrenalectomized, gallamine‐treated rats, suggesting that the effect of noradrenaline released from sympathetic nerve endings contributes to the fall in pH.5. Neither phenoxybenzamine nor propanolol alone significantly reduces the acidaemic response in gallamine‐treated rats, but a combination of the two antagonists almost abolishes the effect. Hence the acidaemia is mediated through effects of catecholamines on both α‐ and β‐adreno‐receptors.6. Since acidaemia affects responses to sympathetic nerve stimulation and sympathomimetic amines, the significance of these observations is discussed with reference to the use of the pithed rat preparation for assessment of drugs affecting adrenergic mechanisms.