bluuebunny/crossref_metadata_2025_split huggingface dataset:
The carotid chemoreceptor input to the respiratory neurones of the nucleus of tractus solitarius
Authors: Lipski J. , McAllen R. M. , Spyer K. M. 
Published: December 2014

1. An investigation has been made into the connexions between the carotid body chemoreceptors and the dorsal respiratory neurones of the cat's medulla.2. In confirmation of previous work these neurones were found to be all inspiratory in firing pattern and to fall into two categories, Rα (forty‐four units) which fire only with the central inspiratory rhythm and Rβ (thirty‐two neurones) that are also excited by lung inflation. Both categories were shown to be excited by stimuli delivered to the carotid bodies during inspiration but, with a single exception, not during expiration.3. When Rβ neurones were made to fire tonically in expiration by maintained lung inflation, chemoreceptor activation inhibited this discharge in 7/11 cases, the remainder being unaffected.4. Iontophoretically applied
DL‐homocysteic acid or glutamate made both Rα and Rβ neurones fire tonically in expiration. Chemoreceptor stimulation during expiration inhibited this activity in all neurones tested (nine Rα and three Rβ cells).5. Using the measurement of the antidromic latency to spinal stimulation as an index of membrane potential, evidence was obtained that any subthreshold influence of the chemoreceptors on dorsal respiratory neurones during expiration was inhibitory (9/18 cases).6. It is concluded that chemoreceptors do not even subliminally excite dorsal inspiratory neurones during expiration; such influence as they have then is inhibitory. Possible reasons for this difference in chemoreceptor influence during inspiration and expiration are discussed. It is suggested that chemoreceptor excitation reaches them only as part of an enhanced central inspiratory drive from an as yet unknown source.
Stimulus‐secretion coupling in pancreatic acinar cells: influences of external sodium and calcium on responses to cholecystokinin‐pancreozymin and ionophore A23187
Authors: Kanno T. , Saito A. , Sato Y. 
Published: December 2014

1. The roles of Na and Ca ions in stimulus‐secretion coupling were analysed in the isolated and perfused rat pancreas.2. Partial replacement of NaCl with LiCl produced a diminution in both amylase output and pancreatic juice flow which were induced by 5 m‐u. CCK‐PZ/ml., and almost normal responses were usually regained immediately after the reintroduction of a standard concentration of NaCl. Nearly total replacement of NaCl with LiCl caused an almost complete inhibition of the responses, although 25 m
M‐NaHCO3 and 1 m
M‐NaH2PO4 were still present, and only partial recovery was obtained after the re‐introduction of a standard concentration of NaCl.3. A quantitative relationship was found between the amount of amylase released by CCK‐PZ and the [Na+]o over the range 26‐157 m
M in the presence of 2·5 m
M‐Ca. A similar relationship was also observed when [Ca2+]o was decreased to 1·0 m
M, but the responses were reduced to about one half of those observed with 2·5 m
M‐Ca.4. The most satisfactory theory which explains the cellular mechanism of CCK‐PZ‐induced amylase output, and which fits the experimental data, requires the dominant activity of a complex composed of a carrier molecule bearing one Ca and four Na molecules, if there is no interaction between Na+ and Li+.5. A quantitative relationship was also found between the amount of pancreatic juice flow stimulated by CCK‐PZ and [Na+]o, over the range 26‐157 m
M, in the presence of 1·0 or 2·5 m
M‐Ca.6. A similar quantitative relationship was found between the amount of amylase released by Ca‐ionophore A23187 and [Na+]o in the presence of 2·5 or 5·0 m
M‐Ca. The most satisfactory theory which fits this experimental data also requires the dominant activity of a complex composed of a carrier molecule bearing one Ca and four Na molecules, if there is no interaction between Na+ and Li+.
The force of contraction of the human ciliary muscle during accommodation
Authors: Fisher R. F. 
Published: December 2014

1. Apparatus has been designed to alter the shape of the human lens by tensile forces applied to the zonular fibres indirectly through the ciliary body. The changes in dioptric power of the lens for monochromatic sodium light were measured at the same time. Simultaneous serial photography, and direct measurement enabled one to relate a change in shape of the lens to the change in dioptric power. Subsequently, the same lens was isolated and spun around its antero‐posterior polar axis and high speed photography recorded its changing profile.2. By comparing the changes in lens profile due to zonular tension and centrifugal force respectively, the force developed in the zonule for a given change in the shape of the lens could be calculated. Changes in dioptric power associated with those of shape can thus be related directly to the force of contraction of the ciliary muscle necessary to reduce the initial tension of the zonule in the unaccommodated state.3. The force of contraction of the ciliary muscle as measured by radial force exerted through the zonule and the change in dioptric power of the lens were not linearly related. The relationship is more exactly expressed by the equation [Formula: see text] where D = amplitude of accommodation in dioptres (m−1), F
CB = force of contraction of the ciliary muscle as measured by changes in tension of the zonule (N), Kdf = dioptric force coefficient and is constant for a given age (m−1N−½ × 102·5). This coefficient is 0·41 at 15 yr and 0·07 at 45 yr of age.4. In youth for maximum accommodation (10‐12 D) the force is approximately 1·0 × 10−2 N while to produce sufficient accommodation for near vision (3·5 D) the force is less than 0·05 × 10−2 N.5. After the age of 30 yr the force of contraction of the ciliary muscle necessary to produce maximum accommodation rises steadily to about 50 yr of age and thereafter probably falls slightly. At about 50 yr of age the ciliary muscle is some 50% more powerful than in youth.6. Even if hypertrophy of the muscle did not occur the amplitude of accommodation would be reduced at the most by only 0·8 D of that observed at the onset of presbyopia.
A role for endogenous prostaglandins in the short‐circuit current responses to osmolal changes in isolated frog skin
Authors: Hall W. J. , O'Regan M. G. , Quigley C. 
Published: December 2014

1. Reduction in osmolality of the Ringer solution bathing the morphological inside of frog skin (by lowering the NaCl concentration) caused a significant increase in sodium transport as measured by the short‐circuit current. Pretreatment of the skin with acetylsalicylic acid (2·5 × 10−4
M) abolished the short‐circuit current and open‐circuit potential responses to osmolal change.2. The output of prostaglandin‐like material from isolated frog skin was increased by incubating the skin in hypotonic Ringer solution.3. The cyclic AMP levels of isolated frog skin were also increased by a reduction in the osmolality of the Ringer fluid bathing the skin.4. Prostaglandin‐like material was released both by the separated epithelial and dermal layers of frog skin and the output from both layers, on a unit wet weight basis, did not differ.5. The output of prostaglandin‐like material from the separated layers of the skin was substantially greater than from whole skin. Indomethacin (6 × 10−6
M) reduced the output of this material by more than 90% from both layers.6. The release of prostaglandin‐like material from the separated layers of the skin was not altered by a reduction in osmolality of the bathing medium.7. It is concluded that a reduction in the osmolality of the solution bathing frog skin stimulates prostaglandin production and that the increased level of prostaglandins stimulates transepithelial sodium transport by stimulating cyclic AMP accumulation. It is also concluded that the response to osmolal change can only occur in intact skin since separation of the epithelial and dermal layers abolished the increase in the release of prostaglandin‐like material to osmolal change. The site of the increased prostaglandin production and the exact nature of the stimulus remain to be determined.
Responses of visual, somatosensory, and auditory neurones in the golden hamster's superior colliculus
Authors: Chalupa Leo M. , Rhoades Robert W. 
Published: December 2014

1. The response characteristics of visual, somatosensory, and auditory neurones in the golden hamster's superior colliculus were investigated.2. As has been noted for other mammalian species, a distinct difference between the functional organizations of the superficial and deeper layers of the superior colliculus was observed.3. Neurones in the superficial layers were exclusively visual, with small receptive‐fields, and generally did not show response decrements with repeated stimulation. The sizes of the receptive‐fields did not vary appreciably as a function of retinal eccentricity.4. In the deeper layers, visual receptive‐fields were large, or could not be accurately delimited, and response habituation was often evident. In addition, many cells in the deeper layers of the colliculus responded only to somatosensory stimuli. Far fewer cells, which appeared to be confined to the caudal portions of the colliculus, responded to auditory stimuli. Polymodal cells were also encountered.5. Selectivity to opposing directions of movement was tested for ninety‐four visual cells. Using a ‘null’ criterion, 27·7% of these cells were judged to be directionally selective. A distribution of the preferred directions of these cells showed a significant preference for movement with an upper‐nasal component. With a statistical criterion, 60·6% of these cells were considered to show a significant asymmetry in responding to movement in opposing directions.6. Directional selectivity was also tested for ninety‐two cells following acute, unilateral, lesions of the visual cortex. For the eighty cells recorded, homolateral to the ablated cortex, 27·5% were judged as directionally selective using the statistical criterion, while 12·5% were selective with the ‘null’ criterion. Of the twelve cells isolated in the colliculus, contralateral to the lesions, seven were judged as directionally selective with the statistical, and three with the ‘null’ criterion.7. The effects of visual cortical lesions upon directional selectivity appeared to be confined to cells in the superficial layers of the colliculus. It was suggested that directional selectivity of many cells in the superficial layers of the tectum of the hamster is organized cortically.8. A clear spatial correspondence was observed for the receptive‐fields of visual, somatosensory, and auditory neurones.9. As has been suggested for other species, the hamster's superior colliculus appears to play an important role in orienting the animal toward visual, somatosensory, and auditory stimuli.
Calcium and stimulus‐secretion coupling in the mast cell: stimulant and inhibitory effects of calcium‐rich media on exocytosis
Authors: Douglas W. W. , Kagayama M. 
Published: December 2014

1. Isolated rat peritoneal mast cells incubated in Ca‐free media for 2 h, with or without EDTA, and observed by phase‐contact microscopy, became ‘bubbled’ in appearance when subsequently exposed to media rich in calcium (16‐110 m
M).2. Electron microscopy showed the response to be ‘compound’ exocytosis of the sort elicited by conventional mast cell secretagogues such as antigen (in sensitized cells) and 48/80.3. The response to Ca was inhibited by withdrawing glucose and adding dinitrophenol and was thus energy‐dependent.4. Mg in similarly high concentration had no such stimulant effect on Ca‐deprived cells, and excess Ca stimulated only after Ca deprivation.5. It is suggested that Ca deprivation may increase the permeability of the plasma membrane of the mast cell thereby allowing some Ca, when subsequently introduced in high concentration, to penetrate and activate exocytosis; and the results are considered further support for the postulated mediator function of Ca in stimulus‐secretion coupling.6. Two inhibitory effects of calcium in high concentration were detected: (a) suppression of migration or expulsion of granules from the exocytotic pits within the cellular domain; and (b) diminished sensitivity to 48/80.
The morphology of spinocervical tract neurones revealed by intracellular injection of horseradish peroxidase (cat)
Authors: Brown A. G. , Rose P. K. , Snow P. J. 
Published: December 2014

1. The morphology of physiologically identified spinocervical tract neurones was studied using the intracellular injection of horseradish peroxidase in anaesthetized cats.2. Thirty‐six spinocervical tract neurones were reconstructed from serial sections of the lumbosacral spinal cord, cut in either the transverse or longitudinal planes.3. Horseradish peroxidase provided a more complete picture of the dendrites of spinocervical tract neurones than earlier experiments using Procion Yellow injection (Brown, House, Rose & Snow, 1976a). The longitudinal (rostro‐caudal) spread of dendrites from an individual cell was much greater in the present material; neurones in the medial parts of the dorsal horn had dendrites extending for about 500 μm from the soma (1 mm total spread) and neurones in the lateral horn had dendrites extending for about 1 mm from the soma (2 mm total spread). However, the conclusions of the earlier work, on the medio‐lateral and dorso‐ventral extents of dendritic trees, together with the shapes of dendritic trees viewed as reconstructions in the transverse plane, have been confirmed. Dendrites of spinocervical tract cells barely entered lamina II of Rexed: they often ran in the longitudinal direction along the border between laminae II and III for several hundred μm. Dendritic spines were observed on many spinocervical tract neurones.4. Horseradish peroxidase reaction product stained up to 2·5 cm of the axon of spinocervical tract neurones. Axons usually pursued a tortuous path through the grey matter close to the cell body, giving off up to six collaterals before entering the ipsilateral dorsolateral funiculus. In the funiculus, further collaterals often arose at distances of up to 5·5 mm from the soma; these collaterals ran back into the dorsal horn. Collaterals could be traced sometimes to presumed terminal boutons. The majority of collateral terminal arborizations was between the level of the cell body and 500 μm ventral to it (in laminae IV and V). They were, however, in the same medio‐lateral and rostro‐caudal region as the dendritic tree of the parent cell.5. It is concluded that the spinocervical tract must now be considered as having a segmental function, in addition to its function of forwarding information towards the cerebral cortex.
Responses of single units in cat visual cortex to moving bars of light as a function of bar length
Authors: Rose David 
Published: December 2014

1. The responses of single units in the cat's primary visual cortex to moving bars have been examined quantitatively as a function of bar length.2. For about half the cells studied, very long bars evoked weaker responses than short bars, implying that there were inhibitory regions flanking the receptive field centre. In another quarter of the cell sample, there was evidence of flanking regions which were facilitatory in effect.3. The strength of the flanking regions was found to vary from cell to cell and there was no sudden transition between cells which were ‘hyper‐complex’ and those which were not.4. Within the central region of the receptive field, the responses of most (but not all) cells increased with bar length. About half the cells responded to very short bars or spots of light, but about one in six would not respond at all to short bars.5. Correlations were sought between the properties of cells as simple or complex, their responsiveness to moving spots of light, the size of their receptive field centre and the polarity, strength and size of their receptive field flanks. Simple and complex cells with small receptive fields were more likely to respond well to spots, and to have strong inhibitory flanks.6. Correlations were also sought between the above properties and several other parameters of cell behaviour. Cells with strong inhibitory flanks were found to be more broadly tuned for orientation. Individual cells were also more broadly tuned for the orientation of short bars than of long bars.7. Evidence was obtained that spatial summation can be linear or non‐linear for different cells.
Spontaneous histamine secretion from mast cells in the presence of strontium
Authors: Foreman J. C. 
Published: December 2014

1. Histamine secretion from rat peritoneal mast cells occurs spontaneously in the absence of an external stimulus. Spontaneous secretion increases as the concentration of Sr in the extracellular medium is raised from 1 to 10 m‐mole/l. Ca 0.1‐10 m‐mole/l. does not increase spontaneous secretion.2. Spontaneous histamine secretion in the presence of Sr occurs slowly compared with evoked histamine secretion, reaching a maximum only after more than 120 min incubation with Sr 10 m‐mole/l. at 37° C and pH 7.6. Phosphatidyl serine, 10 μg/ml., increases the rate of spontaneous secretion in the presence of Sr.3. The spontaneous secretion occurring in the presence of Sr is highly dependent on the extracellular H ion concentration. Maximal secretion occurs at pH 8.4 and only a very limited secretion is detected at pH below 7.6. The rate of spontaneous secretion is also greater at higher pH. Inhibition of secretion caused by lowering the pH can be reversed by raising the Sr ion concentration over a limited range.4. Intact glycolytic and oxidative metabolism is required for the spontaneous secretion of histamine in the presence of Sr. Removal of extracellular glucose inhibits the secretion by about 80%, and the further addition of inhibitors of oxidative phosphorylation almost abolishes the secretion.5. Ca, Mg and Mn all inhibit the spontaneous secretion of histamine which occurs in the presence of Sr. The antagonism of the effect of Sr by Mg appears not to be competitive.6. Dibutyryl cyclic AMP, 10 μmole/l. to 3 m‐mole/l. and theophylline, 30 μmole/l. inhibit spontaneous secretion in the presence of Sr. Cyclic AMP, AMP, and cyclic GMP 10 m‐mole/l. are without effect on the spontaneous secretion. The inhibitory effect of dibutyryl cyclic AMP and of theophylline are dependent on pH: greater inhibition being achieved at lower pH.
The dynamics of the Π1 colour mechanism: further evidence for two sites of adaptation
Authors: Augenstein E. J. , Pugh E. N. 
Published: December 2014

1. The visual pathway that determines Stiles's Π1 colour mechanism was isolated by the auxiliary field technique and studied under dynamic conditions of light adaptation and recovery by threshold measurements.2. The time courses of adaptation to Π1‐equated short wave‐length (μ ≤ 500 nm) and long wave‐length (μ ≥ 550 nm) fields are very distinct: a large and relatively long‐enduring transient threshold elevation occurs at the onset of the long wave‐length, but not of the short wave‐length fields.3. Similarly, the time courses of recovery from Π1‐equated long and short wave‐length fields are quite distinctive: a large and relatively long enduring transient (‘transient tritanopia’) occurs at the offset of the long wave‐length, but not of the short wave‐length fields.4. The wave‐lengths of the fields which cause the adaptation transients coincide with those shown previously (Pugh, 1976) to combine non‐additively with μ = 430 nm fields in effecting Π1 adaptation. The failure of the time course of Π1 adaptation to be spectrally ‘univariant’ combines with the failures of field‐additivity to demonstrate that signals from the long and/or middle wave‐length sensitive cones affect the adaptation state of the Π1 pathway.5. The adaptation transients are not observed in the pathways that determine Π4 and Π5. Thus, instantaneous signals from the middle and/or long wave‐length sensitive cones are not the cause of the transients. Rather the cause must lie in the path by which those cones transmit their signals to the Π1 pathway or in the Π1 pathway itself.6. The off‐transient can be diminished by adding an adequately intense short wave‐length field to a long wave‐length field that would normally cause it. The Π1 pathway must receive chromatically opponent signals.
An investigation of the ionic mechanism of intracellular pH regulation in mouse soleus muscle fibres
Authors: Aickin C. Claire , Thomas R. C. 
Published: December 2014

1. Intracellular pH (pHi) of surface fibres of the mouse soleus muscle was measured in vitro by recessed‐tip pH‐sensitive micro‐electrodes. pHi was displaced in an acid direction by removal of external (NH4)2SO4 after a short exposure, and the mechanism of recovery from this acidification was investigated.2. Removal of external K caused a very slow acidification (probably due to the decreasing Na gradient) but had no effect on the rate of pHi recovery following acidification. This indicates that K+—H+ exchange is not involved in the pHi regulating system.3. Short applications of 10−4
M ouabain had no obvious effect on pHi and did not alter the rate of pHi recovery following acidification. This suggests that there is no direct connexion between the regulation of pHi and the Na pump.4. Reduction of external Ca from 10 to 1 m
M caused a transient fall in pHi, but the rate of pHi recovery following acidification was unaffected. This suggests that Ca2+—H+ exchange is not involved in the pHi regulating system.5. An 11% reduction in external Na caused a significant slowing of pHi recovery following acidification. 90% or complete removal of external Na almost stopped pHi recovery. This suggests that Na+—H+ exchange is involved in pHi regulation.6. Amiloride (10−4
M) reversibly reduced the rate of pHi recovery to much the same extent as removal of external Na. Its effect was not additive to that of removal of external Na.7. Internal Na ion concentration ([Na+]i), measured using Na+‐sensitive micro‐electrodes, fell on application of (NH4)2SO4 and increased on its removal. The increase transiently raised [Na+]i above the level recorded before (NH4)2SO4 application. This overshoot of [Na+]i was almost completely inhibited by amiloride. This is consistent with the involvement of Na+—H+ exchange in the pHi regulating system.8. Removal of external CO2 or application of SITS (10−4
M) caused some slowing of the rate of pHi recovery following acidification by removal of (NH4)2SO4. The effect of SITS was additive to that of Na‐free Ringer or amiloride. These results suggest that Cl−—HCO3− exchange is also involved in the pHi regulating system and that it is a separate mechanism. Under the conditions used, Cl−—HCO3− exchange formed about 20% of the pHi regulating system.9. Decreasing the temperature from 37 to 28 °C not only caused an increase in pHi, but also considerably slowed the rate of pHi recovery following acidification. We have calculated a Q10 for Na+—H+ exchange of 1·4 and for Cl−—HCO3− exchange, 6·9.10. We conclude that the pHi regulating system is comprised of two separate ionic exchange mechanisms. The major mechanism is Na+—H+ exchange, which is probably driven by the transmembrane Na gradient. The other mechanism is Cl−—HCO3− exchange, which probably requires metabolic energy.