bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two classes of slowly adapting mechanoreceptor fibres in reptile cutaneous nerve
Authors: Kenton B. , Kruger L. , Woo M. 
Published: December 2014

1. The myelinated fibre spectrum of the plantar nerve of reptile consists of a unimodal distribution corresponding approximately to the delta elevation in mammalian nerve and contains a variety of receptor categories similar to those of mammals except for the obvious absence of structures related to hairs.2. The various receptor types of reptilian skin do not fall into discrete groups on the basis of conduction velocity.3. Only a few thermoreceptor fibres were identified but a large proportion of slowly adapting mechanoreceptors responded to rapid temperature transients.4. Two distinct categories of slowly adapting receptors whose discharge is related to the amplitude of skin displacement have been identified and studied in detail. These two receptors can be distinguished by their patterns of discharge, and display several distinctive features including differences in resting discharge, receptive field size, threshold, response to DC polarization, etc.5. The mathematical functions describing the response to stimuli of varying magnitude for one receptor type is markedly affected by the sequence of stimulus presentation.
Determination of extracellular space and intracellular electrolytes in rat liver in vivo*
Authors: Williams J. A. , Woodbury D. M. 
Published: December 2014

1. Uptake of a number of isotopically labelled extracellular tracers by rat liver in vivo was studied.2. A residual intravascular space of 3·0–3·5% following exsanguination was measured by use of [51Cr]red cells. This space was significantly greater than that of skeletal muscle and was also greater in nephrectomized as compared to intact rats.3. [131I]albumin and polyvinylpyrolidine (PVP) were found to distribute initially in a space of 6–7% and this was followed by a delayed rise that was greater for PVP. The extravascular portion of this space is termed the large‐molecule accessible space and is believed to correspond to the histological space of Disse.4. [14C]sucrose and inulin initially distribute in a space of 10–12% followed by a continued late increase. This initial space is termed the small molecule accessible space and is thought to include most of interstitial space.5. 36Cl− and stable Na+ and Cl− spaces were constant at 19–21% and can be used to put an upper limit on extracellular space.6. Operationally, the 1 hr inulin space in the nephrectomized rat was felt to be the best indicator of extracellular space.7. Total electrolytes were measured and intracellular values of 22, 165 and 22 m‐mole/l. cell water for Na+, K+ and Cl−, respectively, were calculated.8. By use of [14C]DMO, an intracellular pH of 7·25 and an intracellular HCO3− of 13 m‐mole/l. cell water were calculated.
Sodium transport across the isolated epithelium of the frog skin
Authors: Aceves J. , Erlij D. 
Published: December 2014

1. A method to separate the epithelium from the underlying layers of the frog skin is described. The method is based on the combined use of collagenase and hydrostatic pressures.2. The potential difference and the short‐circuit current values of isolated epithelia and whole skins are similar. Na net flux and short‐circuit current are equivalent.3. The time course of changes in potential following rapid changes in composition of the bathing solutions shows that the barrier to K diffusion at the internal surface of the isolated epithelium is larger than the barrier to Na diffusion at the external surface.4. In the isolated epithelium there are 133 m‐mole K+ and 24·7 m‐mole Na/l. cellular water. The amount of extracellular water was considered to be equal to the inulin space.5. Arginine vasopressin (0·1 u./ml.) markedly increased short‐circuit current and potential difference in isolated epithelia. The amount of Na in the epithelium that equilibrated with Na in the external solution was not increased by the hormone.6. Ouabain (10−4
M) reduced short circuit current and potential difference to values close to zero. The ouabain treated epithelia contained an increased amount of Na originating in the internal solution. On the other hand the amount of Na that originated from the external solution was not increased.7. The amount of epithelial Na that equilibrated with Na in the external solution was 0·009 μ‐equiv/cm2. This figure is about ten times smaller than the values found in whole skins.
On the control of glycogenolysis in mammalian nervous tissue by calcium
Authors: Landowne D. , Ritchie J. M. 
Published: December 2014

1. A study has been made of the increase in fluorescence of the desheathed cervical vagus nerve that occurs after electrical stimulation (usually 5 sec at 30/sec) of its non‐myelinated fibres.2. At room temperature this increase in fluorescence is normally masked by the decrease in fluorescence caused by mitochondrial oxidative phosphorylation. However, at higher temperatures (30–35° C) the increasing fluorescence phase predominates and the net change on stimulation is an increase.3. At room temperature the increase in fluorescence is seen clearly only when ATP splitting has been prevented by ouabain, by bathing the nerve in lithium‐Locke solution, or when oxidative phosphorylation has been prevented by metabolic inhibitors.4. The increasing fluorescence response is absent when calcium is removed from the external medium; it increases with increasing calcium concentration.5. It is argued that the increasing fluorescence response is due to an increase in glycogenolysis (leading to an increase in the reduced pyridine nucleotide concentration) brought about by the increased calcium entry during the action potential. This calcium presumably increases the activity of phosphorylates a or phosphofructokinase.6. Calcium entry also speeds mitochondrial oxidative phosphorylation.
The release of γ‐aminobutyric acid during inhibition in the cat visual cortex
Authors: Iversen L. L. , Mitchell J. F. , Srinivasan Vasanta 
Published: December 2014

1. The release of γ‐aminobutyric acid (GABA) from the surface of the posterior lateral gyrus of the cerebral cortex was measured by a sensitive enzymic fluorimetric assay procedure. Experiments were performed with anaesthetized cats during resting conditions and during cortical inhibition produced by electrical stimulation of the brain surface or of the lateral geniculate nucleus (l.g.n.).2. The average resting release of endogenous GABA was 0·20 n‐mole/ 7 min.cm2 cortex; this was increased during stimulation of both the cortical surface (2·9 times resting release during monopolar stimulation and 7·4 times resting release during bipolar stimulation) and the l.g.n. (5·7 times resting release).3. Removal of calcium ions from the collection fluid did not affect the resting release of endogenous GABA but prevented the increase in GABA release normally evoked by stimulation of the cortical surface.4. The stimulus parameters used to increase the release of GABA also inhibited the glutamate‐induced firing of single cells in the visual cortex and this inhibition was abolished in the absence of calcium ions.5. In three experiments the total amino acid content of cortical samples was examined using an amino acid analyser. With the exception of GABA, there were no significant differences between the rates of release of any other detected amino acids during periods with and without electrical stimulation of the cortex.6. It is suggested that since the release of GABA observed during inhibitory stimulation of the cortex is calcium‐dependent and specific, it may originate from inhibitory nerve terminals in the cortex. The present findings support the view that GABA is a central inhibitory neurotransmitter.
Voltage clamp studies of a transient outward membrane current in gastropod neural somata
Authors: Connor J. A. , Stevens C. F. 
Published: December 2014

1. Outward directed membrane currents have been studied in voltage clamp experiments on isolated neural somata of the marine gastropod Anisodoris.2. Stepping the membrane potential from a hyperpolarized level to a value in the neighbourhood of resting potential (−35 to −50 mV at 5° C) results in an outward current transient, IA, which is apparently carried by potassium ions.3. The peak amplitude of IA is dependent upon both the holding voltage level and the test step voltage while the time courses of development and decay are independent of, or only slightly dependent on, these parameters.4. The developing and decaying phases of IA are approximated by exponentials, leading to time constants for development of 10–25 msec and for decay of 220–600 msec over the aggregate of cells studied (data at 5° C). Q10 for the processes is approximately 3.5. It is concluded that the transport mechanism for IA is at least operationally distinct from the mechanism underlying delayed outward current, IK.
Site of adrenaline blockade in the superior cervical ganglion of the rabbit
Authors: Christ D. D. , Nishi S. 
Published: December 2014

1. The blocking action of adrenaline on the superior cervical ganglion of the rabbit was investigated with intracellular recording techniques.2. Adrenaline (10−5
M) blocked initiation of post‐synaptic action potentials and decreased the amplitude of excitatory post‐synaptic potentials (e.p.s.p.s), but did not hyperpolarize the post‐synaptic membrane.3. The depressant action of adrenaline was antagonized by phenoxy‐benzamine and dihydroergotamine.4. Acetylcholine depolarizations from iontophoretic ACh were not affected by adrenaline.5. Adrenaline decreased the frequency of miniature excitatory post‐synaptic potentials (m.e.p.s.p.s) and decreased the quantal content of e.p.s.p.s in a low [Ca2+]: [Mg2+] media.6. It was concluded that adrenaline blocks ganglionic transmission by acting at an alpha‐adrenoceptive site in the presynaptic nerve terminals.
The effect of antidiuretic hormone on Na movement across frog skin
Authors: Cereijido M. , Rotunno Catalina A. 
Published: December 2014

1. The effect of antidiuretic hormone (ADH) on the movement and distribution of Na was studied. This was done using three different approaches: (a) the measurement of Na and 22Na in slices of epithelium of skins which were exposed to Ringer of varied composition containing 22Na, (b) the measurement of the influx of Na from the outer to the inner bathing solution with 22Na added to the outside, and (c) the use of a recently introduced technique which permits the direct evaluation of the flux from the outer solution → epithelium, (JOT), i.e. the flux across the barrier which is generally regarded as the site of ADH activity.2. ADH increased the influx from the outer to the inner bathing solution of Na (50%) not only when the concentration of Na on the outside was 115 m
M (i.e. higher than in the epithelium) but even when the concentration was 1 m
M (67%).3. When the skin was bathed with 1m
M‐Na Ringer on the outside, ADH increased the unidirectional Na flux JOT by 56% (Rana pipiens) and 71% (Leptodactylus ocellatus). When the concentration was 115 m
M a small increase (17%) was observed in paired skins of R. pipiens. Under this condition no change was observed in L. ocellatus.4. The amount of epithelial sodium which is labelled by 22Na added to the outside was taken to reflect the amount of Na involved in Na transport across the epithelium. Depending on whether the concentration of Na on the outside was high (115 m
M) or low (1 m
M), ADH produced an increase, or a decrease, of both the total Na content and the amount of 22Na exchanged.5. When the concentration of Na on the outside was low, ADH increased the total influx and JOT in spite of the fact that it lowers the total Na content and does not affect the exchangeable pool of Na. This observation is inconsistent with the view that the effect of ADH is due to the fact that the increased permeability of the outer barrier allows more Na into the cell, and that the resulting increase of Na concentration in the cytoplasm accelerates the Na pumps at the inner side of the cells.6. It is concluded that ADH speeds up Na movements at the outward facing barrier, and that this exchange which facilitates the penetration of Na into a transporting compartment produces also a gain or a loss of Na in compartments not directly involved in Na transport across the epithelium. One compartment which is not involved in Na transport might be the cytoplasm of the epithelial cells.
Primary afferent depolarization and flexion reflexes produced by radiant heat stimulation of the skin
Authors: Burke R. E. , Rudomin P. , Vyklický L. , Zajac F. E. 
Published: December 2014

1. The reflex effects of pulses of intense radiant heat applied to the skin of the central plantar pad have been studied in unanaesthetized (decerebrate) spinal cats.2. Pad heat pulses produced flexion of the ipsilateral hind limb and increased ipsilateral flexor monosynaptic reflexes, due to post‐synaptic excitation of flexor alpha motoneurones. These effects were accompanied by reduction of extensor monosynaptic reflexes and post‐synaptic inhibition of extensor motoneurones.3. Ipsilateral (and contralateral) pad heat pulses consistently evoked negative dorsal root potentials (DRPs) as well as increased excitability of both cutaneous and group Ib muscle afferent terminals. The excitability of group Ia afferents was sometimes also increased during pad heat pulses, but to a lesser extent.4. Pad heat pulses produced negative DRPs in preparations in which positive DRP components could be demonstrated following electrical stimulation of both skin and muscle nerves.5. The motor and primary afferent effects of heat pulses always accompanied one another, beginning after the pad surface temperature had reached rather high levels (usually 48–55° C).6. Negative DRPs increased excitability of cutaneous and group Ib afferents, and motoneurone activation produced by pad heat pulses was essentially unmodified when conduction in large myelinated afferents from the central plantar pad was blocked by cooling the posterior tibial nerve trunk.7. It is concluded that adequate noxious activation of cutaneous afferents of small diameter produces primary afferent depolarization in a variety of large diameter afferent fibres, as well as post‐synaptic effects in alpha motoneurones.
The influence of wind resistance in running and walking and the mechanical efficiency of work against horizontal or vertical forces
Authors: Pugh L. G. C. E. 
Published: December 2014

1. O2 intakes were determined on subjects running and walking at various constant speeds, (a) against wind of up to 18·5 m/sec (37 knots) in velocity, and (b) on gradients ranging from 2 to 8%.2. In running and walking against wind, O2 intakes increased as the square of wind velocity.3. In running on gradients the relation of O2 intake and lifting work was linear and independent of speed. In walking on gradients the relation was linear at work rates above 300 kg m/min, but curvilinear at lower work rates.4. In a 65 kg athlete running at 4·45 m/sec (marathon speed) V̇O2 increased from 3·0 l./min with minimal wind to 5·0 l./min at a wind velocity of 18·5 m/sec. The corresponding values for a 75 kg subject walking at 1·25 m/sec were 0·8 l./min with minimal wind and 3·1 l./min at a wind velocity of 18·5 m/sec.5. Direct measurements of wind pressure on shapes of similar area to one of the subjects yielded higher values than those predicted from the relation of wind velocity and lifting work at equal O2 intakes. Horizontal work against wind was more efficient than vertical work against gravity.6. The energy cost of overcoming air resistance in track running may be 7·5% of the total energy cost at middle distance speed and 13% at sprint speed. Running 1 m behind another runner virtually eliminated air resistance and reduced V̇O2 by 6·5% at middle distance speed.
Influence of lysine‐vasopressin dosage on the time course of changes in renal tissue and urinary composition in the conscious rat
Authors: Atherton J. C. , Green R. , Thomas S. 
Published: December 2014

1. The changes in urinary and renal tissue composition induced by continuous, intravenous infusion of lysine‐vasopressin (2·5, 5, 15 and 60 μ‐u./min. 100 g body wt.) for up to 4½ hr in water‐loaded, conscious rats were determined.2. Both the magnitude of, and the time required to attain, maximal and stable responses, in respect to both urinary and tissue composition, varied with the dose.3. The dose‐dependent changes in medullary composition were compounded of graded decreases in water content and graded increases in solute (mainly Na and urea) content.4. The relative contribution of the changes in water, Na and urea contents varied with time and with dose. Significant increases in papillary urea content occurred with all doses. The range of change in urea content was wider than that for any other solute.5. At low doses, the changes in urinary flow and osmolality were ascribable, almost entirely, to large decreases in free‐water clearance, with minor changes in medullary composition; at higher doses, the increases in urinary osmolality were accompanied by steep increases in medullary solute concentrations.6. A variable, dose‐dependent, transient natriuresis occurred during the phase of increasing medullary Na concentration; the peak natriuresis preceded the times of maximal osmolal and Na concentrations in the papilla and urine.7. The differences in osmolal, urea and Na concentrations between papilla and urine also changed with time.8. Both the transitional and steady‐state changes induced by lysine‐vasopressin are discussed in terms of intrarenal mechanisms. It is concluded that the data are most reasonably interpreted on the basis that several hormone‐sensitive loci exist in the kidneys, each with individual dose—response and kinetic characteristics.
Intracellular concentrations of sodium, potassium and chloride in the salt‐gland of the domestic goose and their relation to the secretory mechanism
Authors: Peaker M. 
Published: December 2014

1. The composition of the nasal salt‐glands of geese was found to be Na 57 ± 3·5 (
S.E.), K 52·3 ± 3·9 and Cl 78·3 ± 11·0 m‐equiv/kg fresh tissue. During secretion, the Na content was significantly raised to 72·4 ± 3·4 m‐equiv/kg.2. Salt‐gland slices incubated in Krebs—Henseleit bicarbonate medium plus glucose (6 m
M), in the presence of [14C]sucrose as an extracellular marker had the following composition, Na 85·3 ± 3·1, K 37·1 ± 3·1 and Cl 74·3 ± 3·6 m‐equiv/kg. The calculated intracellular concentrations were for Na 61·5 ± 2·1, K 105·3 ± 8·7 and Cl 37·8 ± 5·0 m‐equiv/l. intracellular water.3. Ouabain (10−4
M) significantly decreased the tissue and cell K concentration and significantly increased the Na concentration.4. Acetylcholine (10−6
M) and eserine (10−4
M) in the incubation medium had no effect on intracellular composition.5. Raising the Na concentration of the medium to 172 m‐equiv/l. and the Cl to 156 m‐equiv/l. in two experiments had no effect on the calculated intracellular composition.6. These results do not support reports that the cells have a very high Na concentration (about 350 m‐equiv/l. intracellular water). They are compatible with the hypothesis that the hypertonic secretion is formed across the luminal membrane of the secretory cell by an active Na+ pump and there are no data to suggest that Na+ is concentrated across the basal membrane by a ouabain‐insensitive process.7. The data are discussed in relation to permeability studies and to electrical potential measurements within the gland by other workers.
Platelet aggregation and strenuous exercise
Authors: Poller L. , Priest Celia M. , Thomson Jean M. 
Published: December 2014

1. Platelet aggregation in the Chandler's tube has been found to be increased in a group of normal male and female volunteers who undertook strenuous physical exercise. This coincided with acceleration of the ‘intrinsic’ blood clotting system and a rise in fibrinogen. The rise in fibrinogen occurred despite increased fibrinolysis.2. The study confirms the sensitivity of the platelet aggregation system to changes in the ‘intrinsic’ clotting mechanism. Acceleration of this system in this study resulted from a physiological cause and produced accelerated aggregation in the coagulation‐affected phase.
The effect of ACTH on calcium distribution in the perfused cat adrenal gland
Authors: Jaanus Siret D. , Rubin R. P. 
Published: December 2014

1. Experiments were carried out to study the effects of adrenocorticotrophin (ACTH) on calcium distribution in the isolated cat adrenal gland perfused with Locke solution.2. The addition of ACTH to Locke solution caused a small, but significant, increase in the radiocalcium (45Ca) space and content of the adrenal cortex.3. The average 45Ca washout curve obtained after exposure to ACTH was significantly displaced above the average washout curve for the control glands during the first 20 min of washout. During the time that the two curves were significantly different, maximum corticosteroid secretion was attained.4. The rate of 45Ca efflux was slowed after ACTH was added to the perfusion medium.5. The total calcium content of the cortex was not altered by ACTH.6. Perfusion with calcium‐free Locke caused a rapid decrease in the calcium content of the cortex to about 20% of the control value. Dinitrophenol was required to deplete completely the cortical calcium content during perfusion with the calcium‐deprived medium.7. The results are consistent with the suggestion that a translocation of calcium occurs during stimulation of the cortex by ACTH. The source of the calcium ions needed to support the secretory response to ACTH is probably not the extracellular fluid; but ACTH may shift calcium from a rapidly exchanging to a more slowly exchanging cellular pool.
Effect of ouabain and metabolic inhibitors on the Na and K movements of nucleotide contents of L cells
Authors: Lamb J. F. , MacKinnon M. G. A. 
Published: December 2014

1. The general characteristics and Na and K movements of L cells (derived from mouse epithelium) have been measured. Both cells grown in suspension (LS cells) and as a monolayer (L cells) were used.2. The volume of L cells was 1·2 × 10−9 cm3 and of LS cells 3·5 × 10−9 cm3; of this 82% was water.3. Electron micrographs showed the presence of numerous protrusions (filopodia) from both forms of the cell. These had the effect of increasing the surface area of the cell by 2‐4 times over smooth cells of the same volume. On changing from the flattened to the spherical shape during trypsinization, the filopodia altered to maintain a constant V/A ratio.4. These cells contain K, about 170 m‐mole/l. intracellular water and Na, 9 m‐mole/l. intracellular water (L cells only) at 20° C. The K fluxes are 1·9 p‐mole/cm2 sec for LS cells and 0·8 p‐mole/cm2 sec for L cells and the Na fluxes are 1·8 p‐mole/cm2 sec for L cells (expressed as per total cell surface (including filopodia)). If expressed as p‐mole/cell per sec then L and LS cells have the same K flux.5. 10−4
M ouabain reduces the K influx to half, indicating an insensitivity to the glycosides common to the species. In the prolonged presence of ouabain the cells come into a new steady state with a [K]1, of 140 and a [Na]1 of 20–30 m‐mole/l. intracellular water, but a constant [Na + K]1.6. Both DNP (10−3
M) and IAA (10−4
M) are required for maximum inhibition of K uptake, as both aerobic and anaerobic metabolic pathways may be used to drive the pump.7. K removal decreases the Na efflux, and Na removal (eventually) decreases the K influx providing evidence for Na/K coupling.8. The cells contain 7·5 m‐mole/litre intracellular water of ATP, a level some 15 times that of ADP.9. The Na pump in these cells is very similar to that found in other tissues in that (a) it requires K to work, (b) it is blocked by ouabain and metabolic inhibitors and (c) it transports three molecules of Na for each two molecules of K.