bluuebunny/crossref_metadata_2025_split huggingface dataset:
Current—voltage curve of sodium channels and concentration dependence of sodium permeability in frog skin
Authors: Fuchs W. , Larsen E. Hviid , Lindemann B. 
Published: December 2014

1. The inward facing membranes of in vitro frog skin epithelium were depolarized with solutions of high K concentration. The electrical properties of the epithelium are then expected to be governed by the outward facing, Na‐selective membrane.2. In this state, the transepithelial voltage (V) was clamped to zero and step‐changes of Na activity in the outer solution ((Na)o) were performed with a fast‐flow chamber at constant ionic strength, while the short‐circuit current was recorded.3. At pre‐selected times after a step‐change of (Na)o the current response (I) to a fast voltage staircase was recorded. This procedure was repeated after blocking the Na channels with amiloride to obtain the current—voltage curve of transmembrane and paracellular shunt pathways. The current—voltage curve of the Na channels was computed by subtracting the shunt current from the total current.4. The instantaneous INa—V curve thus obtained at a given (Na)o could easily be fitted with the constant field equation in the range between ‐50 and zero mV. This fit yielded approximate estimates of PNa, the Na— permeability of the Na‐selective membrane (at this (Na)o) and the cellular Na activity, (Na)c. As residual properties of the serosal membrane were ignored the computed values are expected to underestimate the true ones.5. At constant (Na)c, the steady‐state value of 1/PNa increases linearly with (Na)o. Error analysis and the effect of drugs show that the dependence is not due to the residual properties of the inward facing membranes but reflects the true behaviour of PNa.6. The steady‐state PNa at a given (Na)o is smaller than the transient PNa observed right after a stepwise increase of (Na)o to this value. The time constant of PNa‐relaxation is in the order of seconds.7. In conclusion, Na transport through open Na‐selective channels of the outward facing membrane of the stratum granulosum cells can be described as an electrodiffusion process which as such does not saturate with increasing (Na)o. However, when added to the outer border of the membrane Na causes a decrease of PNa within several seconds. It is considered that binding of Na results in closure of Na channels.
Human erythrocyte anion permeabilities measured under conditions of net charge transfer
Authors: Hunter M. J. 
Published: December 2014

1. The permeability of the human erythrocyte to anions has been measured under conditions of net charge transfer: for Cl− and HCO3− ions, at 37° C, this permeability is 5 orders of magnitude too small to account for the rate of the electroneutral anion exchange which is responsible for the chloride, or Hamburger, shift.2. The method is an indirect one in which the ionophore, valinomycin, is used to increase the erythrocyte K+ permeability: in the absence of permeant cation externally, the rate of the resulting K+ efflux may be limited by the slowness of the accompanying anion efflux, allowing the true anion permeability to be estimated.3. The average Cl− permeability estimated in ACD‐stored erythrocytes (seven experiments) and erythrocytes from fresh blood (two experiments) was 2·1 × 10−8 cm/sec at 37° C and pH 7·4: this may also be expressed as a Cl− conductance of about 1·0 × 10−5 Ω−1 cm−2. The apparent activation energy for net efflux of Cl− was found to be 3·9 kJ/mole (16·4 kcal/mole).4. In fresh cells, the ratios of Cl−, HCO3−, Br− and I− permeabilities (or conductances) were 1:0·8:1·5:5. The three halide ions follow Eisenman's Sequence I, representing a binding site of low field strength.
Daily changes in the blood composition of conscious pigs with catheters in foetal and uterine vessels during late gestation
Authors: Randall G. C. B. 
Published: December 2014

1. Catheters were inserted into the foetal carotid artery and maternal middle uterine artery and vein in twenty foetuses from fifteen sows, 91‐105 days pregnant. Blood samples were collected from foetal and maternal circulations for periods of 7‐21 days after surgery.2. Blood gas tensions, pH, packed cell volume (PCV) and the levels of glucose, fructose and lactic acid in conscious pigs were followed in foetal and maternal bloods during late pregnancy.3. Foetal blood gas tensions, pH, PCV, lactic acid and glucose levels did not change markedly during the last 20‐25 days of gestation. Blood fructose concentration fell during this period with the greatest change occurring after 100 days gestation. Foetal and maternal blood pH values were higher than those reported in the sheep, cow, mare and rhesus monkey.4. Small changes in PCO2 and pH in foetal carotid blood were associated with similar changes in maternal uterine venous blood, so that gradients between sow and foetus remained relatively constant.5. Daily changes in maternal blood glucose levels were associated with smaller changes in foetal blood glucose and fructose levels. Blood glucose concentrations in foetal blood were generally 40‐70% of maternal concentrations. Over‐all relationships between maternal blood glucose and foetal blood fructose concentrations were masked by the independent fall in foetal fructose levels with age.6. The present findings have been compared with previous observations on acute, anaesthetized preparations in pigs, and chronic preparations in other domestic animals.
Effects of fusimotor stimulation on the response of the secondary ending of the muscle spindle to sinusoidal stretching (cat)
Authors: Cussons P. D. , Hulliger M. , Matthews P. B. C. 
Published: December 2014

1. The responsiveness of the spindle secondary ending to sinusoidal stretching has been studied using the soleus muscle of the anaesthetized cat. The sensitivity (impulses/sec firing per mm stretching) and the phase of the response were determined by computer averaging. The small linear range was studied at frequencies of 0·5‐500 Hz, and also the larger non‐linear range at 1 Hz.2. In the linear range, stimulation of single fusimotor fibres (which were presumed to be static axons) approximately halved the sensitivity of the ending to low frequency stretching (up to 30 Hz), but did not produce any change in the phase of the response. Thus, from the point of view of motor function, fusimotor activity provides control of gain and a biasing signal, but not control of the relative sensitivity of the secondary ending to length and velocity.3. In contrast, such stimulation slightly increased the responsiveness of the secondary ending to high‐frequency stretching (100‐500 Hz) and slightly advanced the phase of the response above that of the passive ending.4. The results are discussed in relation to the effect of static fusimotor stimulation on the primary ending, and to findings on secondary endings in the decerebrate cat.
Kinetics of synaptic transfer from receptors to ganglion cells in turtle retina
Authors: Baylor D. A. , Fettiplace R. 
Published: December 2014

1. Synaptic transfer between the retinal input and output was studied in turtle eyecups by injecting rectangular current pulses into a single cone or rod while recording externally from a ganglion cell.2. When a receptor was activated with weak steps of polarizing current, the probability of obtaining a ganglion cell impulse rose after an S‐shaped delay to a peak at about 0·1 sec and then declined. This suggests that the transmission chain behaves like an electrical band‐pass filter containing delay and differentiating elements.3. To further characterize the kinetics of excitation in the subthreshold region, the duration and polarity of the polarizing current pulses were varied while determining the magnitude of the threshold current and the delay to the ganglion cell impulses. The results of these experiments were described with linear models which assume that synaptic transfer occurs over a cascade of first‐order delay stages and a single differentiating stage.4. The pathways which relay off responses to light from rods and red‐sensitive cones were formally similar, but the time scale in the rod path was several times slower. The path carrying off responses from the red‐sensitive cones was faster than the on path. These kinetic differences indicate that independent pathways mediate each of the three categories of response and suggest that the kinetics of each path are ‘matched’ to the input signals generated by light.5. The strength—latency relations for the responses of on‐centre ganglion cells to flashes and steps of light were approximately predicted from the description of synaptic transfer developed here and the description of visual transduction in red‐sensitive cones from a previous study.6. It is suggested that the retinal paths have kinetics which might be useful in transmitting light‐evoked signals whilst attenuating noise present near the input.
Antagonism by indomethacin of neurogenic hyperthermia produced by unilateral puncture of the anterior hypothalamic/preoptic region
Authors: Rudy T. A. , Williams J. W. , Yaksh T. L. 
Published: December 2014

1. In unanaesthetized rats, restrained at an ambient temperature of 24 °C, the anterior hypothalamic/preoptic (AH/PO) region was lesioned unilaterally by acute mechanical puncture.2. In control (no pre‐treatment) rats, unilateral AH/PO puncture produced a neurogenic hyperthermia which began immediately, reached its peak magnitude (mean peak magnitude = +2.3 °C) within 60‐90 min and persisted usually for 8‐16 hr. At defervescence, core temperature fell to a level near that of the pre‐lesioning base line.3. The prostaglandin synthesis inhibitor, indomethacin, administered
I.P. at doses of 5 and 15 mg/kg 1 hr before puncture of the AH/PO region, attenuated the lesion‐induced hyperthermia in a dose dependent fashion. The higher dose reduced peak magnitude by 80% and the 6 hr Fever Index by 88%. The vehicle used to dissolve the indomethacin (60% DMSO/40% saline) did not significantly attenuate the hyperthermia.4. In rats that were hyperthermic after AH/PO damage, indomethacin (10‐15 mg/kg
I.P.) caused core temperature to fall promptly to near the prelesion base line. Reversal occurred whether the indomethacin was injected while core temperature was still rising or late in the plateau phase of the hyperthermia.5. It is suggested that the neurogenic hyperthermia elicited by unilateral lesioning of the AH/PO region was mediated by prostaglandins released from injured tissue and possibly from extravasated blood. Evidence is cited indicating that the most likely sites of action of the released prostaglandins are the surviving portion of the AH/PO region on the punctured side and the intact contralateral AH/PO region.
The morphology of hair follicle afferent fibre collaterals in the spinal cord of the cat
Authors: Brown A. G. , Rose P. K. , Snow P. J. 
Published: December 2014

1. The enzyme horseradish peroxidase (HRP) was injected into single axons that innervated hair follicle receptors to study the morphology of their collaterals in the dorsal horn of the cord. The axons were impaled near the dorsal root entrance zone in the lumbosacral spinal cord of anaesthetized cats and HRP injected by passing current through the intra‐axonal micro‐electrode. The morphology was revealed by subsequent histochemistry.2. Thirteen hair‐follicle afferent fibres were stained including six that innervated tylotrichs (type T hair follicle afferent units) and one that innervated guard hairs (type G unit). The remaining six axons were not classified according to hair type, but, on the basis of their axonal conduction velocities, would have been either type G or T.3. Eleven axons could be traced back into the dorsal roots. Eight of these, upon entering the cord, turned and ran towards the brain. They did not divide into rostral and caudal branches. Three of the eleven did divide and gave rise to both rostral and caudal branches.4. Sixty‐three collaterals were given off the thirteen stained axons. All well‐filled collaterals had a strikingly similar morphology. They descended through laminae I‐III of the dorsal horn into the deeper parts of lamina IV or into lamina V, before turning and ascending back into superficial lamina IV and lamina III where they branched profusely to give rise to their terminal arborizations. Terminal boutons, most commonly of the ‘en passant’ type, were numerous in lamina III, but were also seen in the dorsal part of lamina IV and in ventral lamina II. None were observed in dorsal lamina II or near the junction of the grey and white matter (lamina I) or in lamina V.5. The terminal arborizations of collaterals from a single hair follicle afferent fibre were in line with one another in the longitudinal axis of the cord. In the better‐stained preparations the terminal arborizations of adjacent collaterals from a single axon formed a continuous longitudinal column through the dorsal horn. There was a gradual shift of the column of arborizations from lateral to medial as the more rostral collaterals were given off.6. The hair‐follicle afferent fibre collaterals are now identified as the ‘collaterales grosses et profondes de la substance de Rolando’ of Ramón y Cajal (1909) which give rise to the ‘flame‐shaped arbors’ of Scheibel & Scheibel (1968).7. The importance of the longitudinal organization of the terminal arborizations for an understanding of the topographical properties of dorsal horn neurones is discussed.
Thin‐fibre receptors responding to mechanical, chemical, and thermal stimulation in the skeletal muscle of the dog
Authors: Kumazawa T. , Mizumura K. 
Published: December 2014

1. Unitary activities of muscular thin fibre afferents, which were not sensitive to muscle stretching, were recorded from the nerve of the medial gastrocnemius muscle of the dog. Responses to mechanical stimulation, intra‐arterial injection and local application of chemical solutions, and thermal stimulation of the surface of the muscle were studied. It was observed that polymodal receptors which responded to all types of stimulation existed in the thin fibre afferents of the muscle.2. The receptive area of these units tested by mechanical stimulation was spot‐like and appeared to be located not only on the surface but in the midst of the muscle.3. The mechanical response varied among these units with respect to the threshold and the pattern of discharges.4. In these units, NaCl, KCl, and bradykinin consistently evoked responses, with differences in the latencies and discharge patterns, while solutions of histamine, acetylcholine and sodium citrate caused responses less consistently and less effectively. In the stretch receptors, chemical stimulation applied in the same way as tested in the thin fibre afferents produced quite different features in their responses.5. Heating the receptive area of the muscle surface caused responses in twenty‐five out of thirty‐six units, which were sensitive both to mechanical and to chemical stimulations. The threshold varied from 38·0 to 48·3 °C, with a mean of 43·1 °C for C fibre units and 41 °C for A‐δ fibre units.6. The responses to heating were consistently obtained in the units responding to the surface application of chemical solutions. However, the above response was never obtained in the units which did not respond to surface chemical stimulation but responded to intra‐arterial injection. These results suggest a large population of polymodal receptors in the muscular thin fibre afferents.
Release of endogenous serotonin from two identified serotonin‐containing neurones and the physiological role of serotonin re‐uptake
Authors: Hamon M. , Gerschenfeld H. M. , Paupardin-Tritsch Daniele 
Published: December 2014

1. The amounts of endogenous serotonin (5‐HT) released into the medium by the cerebro‐buccal ganglionic ring of Aplysia californica incubated in artificial sea water (ASW) were measured. The rate of spontaneous 5‐HT release varied between 0·4 and 1·2 p‐mole per hour, which is less than 1% of the total 5‐HT present in this preparation.2. Direct stimulation of the ordinarily silent 5‐HT‐containing giant cerebral neurones resulted in a 80‐100% increase of the 5‐HT released, but only when the 5‐HT uptake was blocked by chlorimipramine (1‐10 μ
M).3. High K+ media (50 m
M) also caused a significant increase in the amount of 5‐HT released from the preparation provided that chlorimipramine (1‐10 μ
M) was present in the incubation fluid.4. Co2+ ions (10‐30 m
M) added to the incubating medium blocked the spontaneous leak of endogenous 5‐HT as well as the release, in the presence of chlorimipramine, evoked either by stimulation of the 5‐HT‐giant cerebral neurones or high K+‐media.5. In the presence of chlorimipramine or desmethylimipramine, the duration and/or the amplitude of the excitatory or the inhibitory synaptic potentials evoked in the buccal neurones by the stimulation of the 5‐HT giant cerebral neurones were markedly enhanced.6. These results strongly support the idea that 5‐HT is the synaptic transmitter released at the excitatory and inhibitory junctions established by the 5‐HT giant cerebral neurones in the ipsilateral buccal ganglia. In addition, they underline the role of amine re‐uptake in the physiological inactivation of 5‐HT as a transmitter.
Oxygen consumption and neonatal sleep states
Authors: Stothers J. K. , Warner Ruth M. 
Published: December 2014

1. In thirty full‐term infants in the first week of life, nursed in a constant volume, closed‐circuit metabolism chamber in a neutral thermal environment (31·5‐33·5 °C), measurements were made of oxygen consumption (V̇O2) during periods of rapid eye movement (REM) sleep and non‐rapid eye movement (NREM) sleep.2. The mean V̇O2 during REM sleep was 5·97 ml. kg−1. min−1. In NREM sleep the mean V̇O2 was 5·72 ml. kg−1. min−1. This difference was significant (paired t test P < 0·05).3. When the direction of sleep state change was taken into account the difference in V̇O2 between the two states was much less when REM sleep preceded NREM than when the change was in the opposite direction. In nineteen infants in whom the change was from REM to NREM the difference in V̇O2 (6·18 and 6·03 ml. kg−1. min−1) was not significant (P > 0·05). The mean difference when the sleep state change was from NREM to REM was significant (P < 0·01), the values being 5·54 and 5·81 ml. kg−1. min−1 respectively.4. In the NREM state, a gradual diminution of V̇O2 with time was consistently found. This was not the case in REM sleep.5. In twelve infants studied in a cool environment (29 ± 0·5 °C) V̇O2 during REM sleep was 7·77, and during NREM sleep it was 6·58 ml. kg−1. min−1, (P < 0·001). Thus even the maximum difference found in a neutral thermal environment of 6·6% was significantly increased to 14·9% (P < 0·01) with mild thermal stress.6. No consistent changes in V̇O2 with time were found in either REM or NREM sleep in twelve infants studied in a cool environment, in contrast to the findings in thermal neutrality
Free water clearance curves during saline, mannitol, glucose and urea diuresis in the rat
Authors: Martinez-Maldonado Manuel , Opava-Stitzer Susan 
Published: December 2014

1. Free water clearances were measured during infusion of hypotonic saline, glucose, urea, and mannitol in Brattleboro rats. For each solute the free water clearances were plotted using either V or (CH2O + CNa) as the distal tubular delivery term.2. In all cases the use of (CH2O + CNa) as distal delivery term yielded a steeper relationship than when V was used. There were no significant differences in the CH2O to V relationship when saline, glucose and mannitol was the solute infused. Urea, however, resulted in a curve with a slope significantly less than that for the other solutes.3. When CH2O was plotted against (CH2O + CNa) there was still no significant difference between the slopes of the curves during saline or mannitol infusion. Use of this delivery term, however, resulted in a slope during glucose infusion which was significantly greater than that during saline or mannitol infusion. The slope for urea infusion remained lower than that for any other solute.4. Regardless of the delivery term used, there was no significant difference in the slopes of the curves for awake Wistar and awake Brattleboro rats during mannitol infusion. This indicates that the awake rat is a suitable model for free water clearance studies.5. The results indicate that NaCl and mannitol are both adequate for free water clearance and that (CH2O + CNa) is a better index of distal delivery than V.
Directional tuning of complex cells in area 17 of the feline visual cortex
Authors: Hammond P. 
Published: December 2014

1. Directional tuning for motion of a field of static visual noise and for motion of bar stimuli against the same stationary noise field as background was compared in eighty‐four deep‐layer complex cells recorded from area 17 of cats, lightly anaesthetized with N2O/O2 supplemented with pentobarbitone. Detailed comparisons of monocular tuning for the dominant eye receptive field were made for seventy‐two cells. Interocular, and stimulus‐dependent ocular dominance differences are reported elsewhere (Hammond, 1978c, and in preparation).2. Directional bias for preferred and opposite directions of motion was enhanced with moving noise fields, compared with moving bar stimuli. Two thirds of cells directionally biased for bars, were directionally selective for noise (33/49); ten of these showed suppression of firing to noise moving in the ‘null’ direction. An additional twenty‐three cells were directionally selective for bar stimuli and for noise, nine with suppression of firing in the null direction.3. A majority of cells (52/62) showed significant differences in preferred directions for bar stimuli and for noise; in an exceptional case, tuning for the two classes of stimuli was orthogonal. Tuning for bar stimuli was usually sharper than for noise. In cells asymmetrically tuned for bar stimuli, tuning was broader for the flank of the tuning curve closest to the preferred direction for noise. Ten cells showed similar tuning for bars and noise; tuning for the remaining ten cells was rather variable or poorly defined.22/62 cells showed bimodal directional tuning to noise, with depression of sensitivity over the range of directions to which the cell responded well with a moving bar stimulus.4. Cells were frequently more responsive to noise‐field motion than to bar motion. Cells with large receptive fields showed greater sensitivity to noise than those with small fields, and were relatively more sensitive to noise than to bar stimuli.5. The results are interpreted as evidence that the directional and orientational sensitivity of complex cells are mediated by different mechanisms.