bluuebunny/crossref_metadata_2025 huggingface dataset:
Variation in the action spectrum of erythrolabe among deuteranopes.
Authors: Alpern M , Pugh E N
Published: December 2014

1. Eight deuteranopes matched a mixture of a monochromatic light on the long wave side of the neutral point and a violet (450 nm) primary to a fixed white as well as a monochromatic light on the short wave side of the neutral point mixed with a red (650 nm) primary, to the same white. For lambda greater than 530 nm, the former set of matches defined the action spectrum of the long wave sensitive foveal cones, and for lambda less than 480 nm, the latter that of the short wave sensitive cones. 2. Individual differences in the former matches were approximately correlated with the respective ratio of the sensitivities of the wave‐length of the anomaloscope primaries, in a way that individual differences of the latter were not. 3. Assuming that eye media differences alone account for the differences in long wave sensitive foveal action spectra, the spectral reflectivity of the foveal fundus was predicted for these deuteranopes. The prediction is inconsistent with measurement. 4. Thirteen deuteranopes matched monochromatic spectral lights with a green (535 nm) and a blue (460 nm) primary. The result were analysed by von Kries' method in which differences in matching due to differences in eye media absorption are obviated. The matches of five differed significantly from one another when so analysed. It was concluded that at least one of two action spectra of the foveal cones of every one of these five differed from that of all of the others. 5. The canon that deuteranopes accept normal colour matches was evaluated by confronting a single normal with five deuternopes in the analytical anomaloscope of Baker & Rushton, set in the mode of each of the five in turn. Obvious differences existed between this normal's matches and those of four of five deuteranopes. 6. Explanations for differences in the spectrum of erythrolabe in different deuteranopes are evaluated. The possibilities that all have the identical visual pigment but (a) in cones with different optical funnelling properties or (b) in different optical densities are considered. Preliminary results are not in agreement with the expectations of either of these ideas. 7. It is suggested that the visual pigment in the foveal long wave sensitive cones of different deuternopes (and of different normals) may have different extinction spectra. The idea is consistent with micro‐spectrophotometric measurements of rhodopsin in individual rods from different frogs (Bowmaker, Loew & Leibman, 1975).
Some properties of the smooth muscle of mouse vas deferens.
Authors: Holman M E , Taylor G S , Tomita T
Published: December 2014

1. Contractions of the mouse vas deferens in response to electrical stimulation differ form those recorded form the guinea‐pig vas deferens in that they are abolished by tetrodotoxin. 2. Changes in membrane potentials were recorded form the smooth muscle of both preparations in response to stimulation with current pulses applied by an intracellular electrode and by alrge extracellular plate electrodes. 3. Both preparations behaved similarly in response to intracellular stimulation. Electrotonic potentials in response to extracellular current pulses spread in a longitudinal direction in the guinea‐pig vas deferens in accordance with the cable‐like properties of this preparation. In contrast, no longitudinal spread of eletrotonus was observed in the mouse vas deferens. 4. Responses to nerve stimulation differed in the two preparations. In the guinea‐pig, single stimuli caused excitatory junction potentials (e.j.p.s) which gave rise to action potentials. Some cells from the mouse vas deferens showed similar e.j.p.s and action potentials, although the threshold for the initiation of action potentials was lower and more variable. 5. The majority of cells in the mouse vas deferens failed to show action potentials in response to a single stimuli even though the amplitude of e.j.p.s was from 35 to 40 mV. This was probably due to the large resting membrane potentials of these cells, as all‐or‐nothing action potentials could be evoked if successive e.j.p.s were allowed to sum with each other or if a depolarizing current pulse was applied at the peak of an e.j.p. 6. The nature of the response to nerve stimulation recorded from differnt cells in the mouse vas deferens could be correlated with the amplitude and time course of the response of the same cell to intracellular stimulation. 7. It is concluded that individual smooth muscle cells in both preparations are probably coupled electrically but that there are few, if any, low resistance pathways in the longitudinal direction in the mouse vas deferens.
Skin temperature during running‐‐a study using infra‐red colour thermography.
Authors: Clark R P , Mullan B J , Pugh L G
Published: December 2014

Infra‐red colour thermography has been used to visualize skin temperatures in two athletes standing and running in an outdoor environment at 20 degrees C and in a climatic chamber at 11 degrees C. Temperature distributions and changes have been recorded on film and analysed. Mean skin temperatures determined by this method have been compared with skin temperatures obtained with a probe thermocouple. During running, skin temperatures were higher over muscles than over other structures and the distribution differed dramatically from that observed before exercise. Regional mean skin temperatures obtained by thermography differed by up to 4 degrees C from those obtained with the thermocouple probe. Overall mean skin temperatures obtained by both methods agreed to within 1‐5 degrees C.
Sucrose absorption by the rat small intestine in vivo and in vitro
Authors: Davidson Ruth E. , Leese H. J.
Published: December 2014

1. The absorption of glucose and fructose derived from sucrose has been studied using in vitro and in vivo loops of the rat jejunum.

2. At low sucrose concentrations (1 and 10 m
M) glucose appeared in the serosal compartment of the in vitro preparation at a faster rate than fructose, but at high sucrose concentrations (50 and 100 m
M) the rates of serosal transfer of the two sugars were similar. Glucose and fructose appeared in the mucosal compartment, with the rate of fructose appearance exceeding that of glucose, at all the sucrose concentrations studied.

3. Phlorizin (5 × 10−5
M) added to the mucosal medium of the in vitro preparation abolished the serosal transfer of glucose derived from 50 m
M sucrose, and reduced that of fructose by 75%.

4. In the absence of sodium ions, the in vitro preparation failed to transfer glucose and fructose derived from 50 m
M sucrose, into the serosal compartment.

5. Glucose was actively accumulated in the whole gut wall of the in vivo preparation to concentrations higher than those in the plasma at 50 and 100 m
M, but not at 10 m
M sucrose concentrations. Fructose was also actively accumulated to about half the extent of glucose, but reached tissue concentrations greater than those in the plasma, at each sucrose concentration.

6. The whole wall concentrations of glucose and fructose derived from sucrose added to the lumen continued to rise when the blood supply to the in vivo preparation was terminated.

7. No increase in the in vivo whole wall concentrations of glucose and fructose were detected when sucrose was added to the lumen together with concentrations of glucose sufficient to saturate the monosaccharide transport systems.

8. The results favour the view that disaccharide hydrolysis and resulting hexose transfer are sequential, separate events.
Inactivation of the asymmetrical displacement current in giant axons of Loligo forbesi.
Authors: Meves H , Vogel W
Published: December 2014

1. Asymmetrical displacement currents ('gating currents') have been recorded in intracellularly perfused squid giant axons by averaging the currents associated with depolarizing and hyperpolarizing pulses. The relation between 'gating current' and Na inactivation was studied by investigating the effect of pulse duration and conditioning pulses. 2. Increasing the pulse duration from 0‐3‐1 msec to 10‐20 msec reduced the off‐response of the 'gating current' to 50‐70% of its normal size; the time constant was 5 msec at +20 mV and 8 degrees C. The decrease of the Na current during a 10‐20 msec pulse was stronger and faster; it decayed to 10‐26% with a time constant of 1‐35 msec. 3. The effect of pulse duration could also be demonstrated by using only depolarizing pulses. The charge displacement at the end of single or averaged depolarizing pulses was smaller for long pulse durations than for short. A long depolarizing pulse was followed by a small long‐lasting tail of inward current. 4. A conditioning depolarizing pulse of 10‐20 msec duration to a potential of ‐30 or +10 mV, followed by a short recovery period at ‐70 mV, decreased the on‐response of the 'gating current'. Its size was reduced to 46‐71% and 61‐94%, respectively, for a recovery interval of 1‐75 and 5 msec at 2‐3 degrees C. The reduction of the Na current, measured under similar conditions, was more pronounced; the Na current was decreased to less than 50% of its normal value. 5. The observations about the effect of pulse duration and conditioning pulses on the 'gating current' are qualitatively consistent with those of Bezanilla & Armstrong (1974, 1975) and support the view that part of the asymmetrical charge displacement is inactivated during a 10‐20 msec depolarization.
Mechanical work and efficiency in level walking and running
Authors: Cavagna G. A. , Kaneko M.
Published: December 2014

1. The mechanical power spent to accelerate the limbs relative to the trunk in level walking and running, Ẇint, has been measured at various ‘constant’ speeds (3‐33 km/hr) with the cinematographic procedure used by Fenn (1930a) at high speeds of running.

2. Ẇint increases approximately as the square of the speed of walking and running. For a given speed Ẇint is greater in walking than in running.

3. In walking above 3 km/hr, Ẇint is greater than the power spent to accelerate and lift the centre of mass of the body at each step, Ẇext (measured by Cavagna, Thys & Zamboni, 1976b). In running Ẇint < Ẇext up to about 20 km/hr, whereas at higher speeds Ẇint > Ẇext.

4. The total work done by the muscles was calculated as Wtot = ǀWintǀ + ǀWextǀ. Except that at the highest speeds of walking, the total work done per unit distance Wtot/km is greater in running than in walking.

5. The efficiency of positive work was measured from the ratio Wtot/Net energy expenditure: this is greater than 0·25 indicating that both in walking and in running the muscles utilize, during shortening, some energy stored during a previous phase of negative work (stretching).

6. In walking the efficiency reaches a maximum (0·35‐0·40) at intermediate speeds, as may be expected from the properties of the contractile component of muscle. In running the efficiency increases steadily with speed (from 0·45 to 0·70‐0·80) suggesting that positive work derives mainly from the passive recoil of muscle elastic elements and to a lesser extent from the active shortening of the contractile machinery. These findings are consistent with the different mechanics of the two exercises.
The physiological rhythms of subjects living on a day of abnormal length.
Authors: Mills J N , Minors D S , Waterhouse J M
Published: December 2014

1. Fourteen subjects, singly or in groups, have been observed while living on a 21 hr day for 8 or 16 experimental 'days' and fifteen other subjects similarly on a 27 hr day. 2. Rhythmic components of body temperature and excretion of various urinary constituents were calculated. 3. On a 21 hr day, for most components and most subjects, two periods were present, one of 21 hr and one of around or somewhat over 24 hr. 4. On a 27 hr day two periods were less often present and a larger number of observed rhythms could be satisfactorily described by a single period, usually between 23 and 28 hr. 5. In subjects spending a second week on a 21 hr day the circadian component was no less prominent than during the first week. 6. When, after life on a 21 hr day, subjects were deprived of knowledge of time, there was evidence that the 21 hr component did not persist. 7. The results are interpreted as evidence of the continuing existance of an influence with a period of around 24 hr, simultaneously rhythmic influences resulting from the subjects' habits. On a 27 hr day there was sometimes evidence of entrainment, yielding an intermediate period. 8. An attempt is made to compare the relative potency of the exogenous and of the persistent circadian influences on the several variables.
Convergence of rod and cone signals in the cat's retina
Authors: Enroth-Cugell Christina , Hertz B. Gevene , Lennie P.
Published: December 2014

1. In an attempt to understand the convergence of rod and cone signals in the cat's retina, ganglion cells that received inputs from both rods and cones were stimulated using lights chosen to excite one or other receptor system or both together.

2. If a mesopic background was chosen to allow the ganglion cell to be excited by a blue‐green test flash primarily through rods and a deep red flash primarily through cones, one light could not be alternated with the other without eliciting a response from the cell.

3. This appears to be a result of the different temporal properties of the scotopic and photopic systems. On the mesopic background responses to blue‐green test flashes were transient. Responses to red test flashes arose with similar latency, but were more sustained.

4. Rod and cone systems responded with similar latencies in the presence of the mesopic background that substantially light‐adapted the rod system but left the full sensitivity of the cone system undiminished. When equivalently light‐adapted, the cone system was faster.

5. When brief flashes that acted through rods were presented with flashes that acted through cones the ganglion cell's response was the sum of the responses to the two flashes presented separately, as long as the flashes were weak. This linear relation ceased to hold when flashes were strong, but the breakdown appears not to be the result of mutual inhibition between rod and cone signals.

6. When a background light excited both rod and cone systems it appeared to reduce sensitivity independently in each.

7. The scotopic and photopic receptive fields of a given ganglion cell always were of the same type, on‐ or off‐centre, and, within the limits of measurement, the central regions of the receptive fields were concentric and both the same size.
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.
Paracellular permeability of extracellular space markers across rat jejunum in vitro. Indication of a transepithelial fluid circuit.
Authors: Munck B G , Rasmussen S N
Published: December 2014

1. The characteristics of [51Cr]EDTA, [3H]methoxyinulin ([3H]MI), [14C]polyethylene glycol‐4000 ([14C]PEG), and [3H]mannitol as markers of the extracellular space (e.c.s.) of isolated mucosa from the rat small intestine have been examined. 2. Unidirectional transmural fluxes across the rat jejunum of [3H]MI, [14C]PEG and [3H]mannitol have been measured in the absence of glucose or in the presence of 28 mM glucose. 3. Assuming that [14C]PEG does not enter the cells, [51Cr]EDTA and [3H]mannitol seem to have access to approximately 50 and 90% of the intracellular water respectively. 4. The commercially availabel [3H]MI had access to a space which exceeded th [14C]PEG space by 10%. Upon purification by gel filtration the high molecular weight fraction of the [3H]MI provided estimates of the e.c.s. identical with the estimates obtained with [14C]PEG. 5. For all the markers used the e.c.s. estimates remained constant between the 40th and 80th min of incubation. 6. In the absence of glucose the transepithelial net fluxes of each of the different markers were zero. In the presence of 28 mM glucose the serosato‐mucosa fluxes of all markers were dramatically increased. The ratio between the serosa‐to‐mucosa and the mucosa‐to‐serosa fluxes increased in the order [3H]mannitol greater than [3H]MI greater than [14C]PEG. 7. The effect of glucose on the flux ratio of the marker substances suggests that glucose‐induced net water transport to the serosa side of the gut wall represents the difference between a transcellular net water transport to the serosal side and a significant paracellular net water transport through the lateral intercellular spaces to the mucosal solution.
A quantitative study of C‐mechanoreceptors in hairy skin of the cat.
Authors: Iggo A , Kornhuber H H
Published: December 2014

1. Single C‐mechanorecptor afferent units were examined by recording from fibres dissected from the saphenous nerves of cats anaesthetized with chloralose. The receptive fields, averaging 4 X 3 mm when 10‐50 X threshold stimuli were used, were in the hairy skin of the leg and foot. 2. The extent and excitability of receptor terminals was tested by two‐and three‐point field studies. The excitability of terminals in one part of the field of a unit could be depressed without affecting the excitability of terminals elsewhere in the field. 3. The afferent units could be excited by both inward and outward movement of the stimulus probe, in appropriate conditions; that is, there was non‐directional sensitivity. 4. After‐discharge was found to depend on restorative movements of the skin, not on a persistence of the response of the receptor to the original movement. 5. The response to mechanical stimulation was slowly adapting with two time constants and the stimulus‐response relationship was exactly described by a power function, with exponents ranging from 0‐6 to 1‐3. 6. The C‐mechanoreceptors could be depressed by rapidly repeated or prolonged mechanical stimulation and the effect was confined to the excited terminals.
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.
Effect of exogenous noradrenaline on local cerebral blood flow after osmotic opening of the blood‐brain barrier in the rat.
Authors: Edvinsson L , Hardebo J E , MacKenzie E T , Owman C
Published: December 2014

1. The regional penetration into the brain of exogenous labelled noradrenaline (following unilateral injection into the internal carotid artery) was correlated with the effect of this amine on regional cerebral blood flow as measured by the [14C]ethanol technique in anaesthetized rats. 2. A hyperosmolar solution of urea was injected into the ipsilateral internal carotid artery to induce osmotic opening of the blood‐brain barrier. 3. The extent of the blood‐brain barrier damage was followed by macroscopic and fluorescence microscopic visualization of systemically injected Evans blue, and by the determination of the brain uptake index for noradrenaline. 4. The extravasation of Evans blue was restricted to the brain areas nourished by the internal carotid artery on the same side as the injection. 5. The normally low penetration of noradrenaline into the brain was enhanced fourfold in those brain regions that showed Evans blue extravasation following the administration of hypertonic urea. 6. In the same regions, the systemic administration of noradrenaline markedly increased local cerebral blood flow, compared to the contralateral hemisphere that was unaffected by the injection of urea. This effect on regional cerebral blood flow was blocked by the beta‐receptor antagonist, propranolol.
Effects of dopamine analogues and antagonists on carotid body chemosensors in situ.
Authors: Llados F , Zapata P
Published: December 2014

1. The effects of dopamine, its analogues and antagonists on the chemosensory discharges originating from carotid bodies in situ were studied in anaesthetized cats. 2. Intracarotid (I.C.) injections of 100 ng or more of dopamine produced transient depression of the frequency of carotid nerve chemosensory discharges. Short term (1‐5 sec) complete inhibition was usually elicited by 2 microgram dopamine. 3. I.V. injections of dopamine also produced inhibition of chemosensory discharges, an effect observed with doses which were still too low to produce changes in systemic arterial pressure. Half‐maximal inhibition (ID50) of chemoreceptors was elicited with a mean dose of 84 ng.kg‐1. 4. I.C. and I.V. injections of apomorphine and amantadine also produced transient inhibition of chemosensory activity. Higher doses of these analogues of dopamine were needed to produce this effect, and the resulting inhibition usually did not silence the nerve discharges. Apomorphine inhibition was slightly more prolonged than that with dopamine. 5. Large doses of amphetamine and tyramine, inducers of dopamine release, did not produce inhibition of chemosensory discharges. 6. The effects of two classes of dopamine antagonists were tested. Dose‐response curves for dopamine and apomorphine inhibition were displaced to the right by administration of phenothiazines (chlorpromazine and perphenazine) and butyrophenones (haloperidol and spiroperidol). In animals treated with perphenazine or spiroperidol, dopamine became a stimulator of chemoreceptor activity. 7. It is suggested that dopamine present in carotid body may operate as a modulator of chemosensory activity.
The rate of recovery of vision after early monocular deprivation in kittens
Authors: Giffin Fred , Mitchell Donald E.
Published: December 2014

1. Fifteen kittens were monocularly deprived of vision by suturing the lids of the right eye together for various periods of time at different ages. A simple behavioural technique was used to assess the immediate effects of the period of monocular deprivation on the visual acuity of the deprived eye as well as the time course of any subsequent recovery.

2. The extent of the recovery of vision was measured under conditions where the animal was either forced to use its deprived eye by performing a reverse suture or where the animal had both eyes open after the initial period of monocular occlusion.

3. The initial effects of monocular deprivation were graded in severity according to the age at which the deprivation was imposed, ranging from apparent blindness in animals deprived at 6 weeks of age to only a small loss of acuity in kittens deprived at 12 weeks of age.

4. The effects of deprivation imposed from birth were particularly severe, leading to a temporary blindness. Nevertheless after a period of time that became progressively longer with increasing deprivation, all animals showed some recovery of pattern vision over the course of the next 2 or 3 months. The extent of this recovery became progressively less as the period of deprivation was prolonged. There was even some recovery of vision (an acuity of 2·5 cycles/deg) in animals that were deprived throughout the duration of the ‘critical period’ to 4 months of age.

5. Direct comparison of the rate of behavioural recovery between animals that were reverse sutured with that of litter‐mates that received binocular input after monocular occlusion to either 45 or 60 days of age proved to be remarkably similar, although the acuity that was eventually attained by the reverse sutured animals was always slightly higher.

6. The recoveries observed after reverse suturing were reasonably well correlated with changes observed in the ocular dominance of visual cortical cells under similar circumstances.

7. Although the recovery in these animals can be accounted for by the simple notion of a competitive interaction between the two eyes, the recovery observed in animals that had both eyes open after the initial period of deprivation cannot be so readily explained. Evidently there must be an additional non‐competitive mechanism of recovery.