bluuebunny/crossref_metadata_2025_split huggingface dataset:
Echo‐location of bats after ablation of auditory cortex
Authors: Suga N. 
Published: December 2014

1. Echo‐location of blinded Yuma bats (Myotis yumanensis) was studied after ablation of the auditory cortex (A.C.). A task of obstacle‐avoidance was given to the bats. Hits and misses of strands were counted, and orientation sounds emitted by the bats during flight were recorded.2. After bilateral ablation of A.C., two bats out of six failed to avoid even large obstacles such as 3·7 mm strands and wall. These bats emitted orientation sounds at a rate of 10–15/sec during flight, but did not change that rate before crossing the obstacles and crashed into them. In these bats, other cortical areas in addition to A.C. were probably ablated.3. In three bats out of six, obstacle‐avoidance performance was quite normal. These bats avoided even 0·2 mm strands with orientation sounds, the repetition rate of which was systematically increased before crossing the obstacles. In two of them, the dorsal half of the inferior colliculus (I.C.) was bilaterally ablated in addition to A.C. But ability to avoid the obstacles was not impaired at all. Their cerebral cortices did not show the normal positive—negative diphasic potential change in response to tonal stimuli, although the normal diphasic potential change was retained in A.C. of bats which could not echo‐locate as a result of bilateral ablation of the main nucleus of I.C. A.C. appeared to be not essential for echo‐location.4. Unilateral ablation of A.C. and the internal capsule had no effect on echo‐location, but bilateral ablation of them usually resulted in death from operational trauma.5. It was suggested that A.C. was less important for sound localization in bats than in cats.
The iodide space in rabbit brain
Authors: Ahmed Nawal , Van Harreveld A. 
Published: December 2014

1. The iodide space in rabbit brain varies greatly depending on the conditions under which it is determined.2. When 131I− only is used the iodide space 4 hr after administration of the marker is of the order of 2%. The iodide content of the cerebrospinal fluid (c.s.f.) is about 1% of that of the serum.3. Depression of the active iodide transport by perchlorate increases the space to 8·2% and the iodide content of the c.s.f. to 26% of that of the serum.4. The active iodide transport can also be depressed by saturation with unlabelled iodide. Up to a serum iodide concentration of 5 m
M the space determined after 5 hr remained constant at 2·7%. The iodide space grew when the serum iodide content was enhanced from 5 to 20 m
M, to become constant at a value of 10·6% on further increase of the serum iodide (up to 50 m
M). The iodide content of the c.s.f. increased in a similar manner as the space with the iodide concentration of the serum to about 1/3 of the serum concentration. The iodide space of the muscle was independent of the plasma iodide content.5. From 4 to 8 hr after administration of 131I− alone or with unlabelled iodide (to a serum concentration of 15 m
M) the iodide space remained relatively constant.6. When 131I− was administered in the fluid with which the ventricles were perfused an iodide space of about 7% was attained after about 5 hr.7. In experiments in which 131I− was administered intravenously and the sink action of the c.s.f. was eliminated by perfusion of the ventricles with a perfusate containing as much 131I− as the plasma, the iodide space was 10·2%. When in addition active iodide transport was depressed by perchlorate the space increased to 16·8%.8. Intravenous administration of labelled and unlabelled iodide (to a serum concentration of 20–40 m
M) and ventricle perfusion with the same concentration of 131I− and unlabelled iodide as in the plasma yielded an iodide space of 20·8%. In similar experiments the iodide concentration of the perfusate was so adjusted that after 5 hr perfusion its iodide content hardly changed during the passage through the ventricles. Under these conditions the iodide concentration of the extracellular and perfusion fluids can be considered to be near equal. The iodide space computed on the basis of the iodide content of the outflowing fluid was 22·5%.9. The large iodide space could be equated with the extracellular space if the iodide remained extracellular. This seems to be the case in the muscle where the iodide space is similar to the inulin space.10. The large effects on the iodide space of perchlorate and saturation with unlabelled iodide in experiments in which the marker was administered intravenously and in the perfusate (7 and 8) suggests the presence of an active iodide transport from the brain extracellular fluid into the blood over the blood—brain barrier.
The effect of membrane polarization on the time course of the end‐plate current in frog sartorius muscle
Authors: Kordaš M. 
Published: December 2014

1. Intracellular recordings of the end‐plate current at different membrane potentials were made, using a voltage‐clamp technique.2. When the membrane potential is varied between about +40 and −120 mV, the half‐decline time of the end‐plate current increases from about 0·6 msec to about 1·6 msec.3. It is suggested that the stability of receptor—mediator complex is affected by the membrane potential.
A comparison of the effect of temperature, metabolic inhibitors and of ouabain on the electrogenic component of the sodium pump in mammalian non‐myelinated nerve fibres
Authors: den Hertog A. , Ritchie J. M. 
Published: December 2014

1. A comparison has been made of the effect of cooling, metabolic inhibitors and of ouabain on the electrogenic component of the sodium pump in mammalian non‐myelinated nerve fibres.2. The hyperpolarization that occurs during the potassium‐activated response that is obtained after a brief period of stimulation (5 sec, 30/sec) in potassium‐free solution was taken as an index of the activity of the pump.3. Cooling decreased the amplitude and rate constant of decay of the potassium‐activated response. The area of the response, which reflects the total amount of sodium that is extruded after activity, remained constant.4. Exposure to the metabolic inhibitors deoxy‐
D‐glucose and cyanide also decreased the amplitude and rate constant of the response; as with cooling, the area remained relatively constant.5. Ouabain, however, reduced the amplitude without reducing the rate constant, which was even sometimes increased with small concentrations of ouabain. The area of the response always decreased therefore.6. The effects applying metabolic inhibitors are thus similar to those obtained on cooling, but differ from those of ouabain.
An electrophysiological analysis of responses from lizard muscle spindles
Authors: Proske Uwe 
Published: December 2014

1. Stretch receptor discharges were recorded in the lizard Tiliqua nigrolutea. Responses were identified as coming from muscle spindles by their ‘in parallel’ behaviour during a twitch.2. Recordings from spindles in the iliofibularis muscle which contains many single innervated fibres revealed spindles which discharged on the rising phase of the muscle contraction. This ‘in series’ response increased in frequency and duration at high resting tensions on the muscle and was attributed to a specific intrafusal contraction.3. The ‘in series’ discharge could be induced by stimulation of only one small filament of the muscle nerve. This suggested a focal intrafusal motor innervation.4. Responses from spindles in the semitendinosus muscle, which contains many multiple innervated fibres provided examples of an ‘in series’ response which could be produced by stimulation of several muscle nerve filaments. This was interpreted as being an example of multiple intrafusal motor innervation.5. Spindles with short or elongated sensory regions were subjected to ‘ramp’ stretches. The presence of distinct phasic and tonic responses from the two types was confirmed and related to the behaviour of mammalian spindles.
Proteolytic activity during the absorption of [131I]γ‐globulin in the new‐born calf
Authors: Hardy R. N. 
Published: December 2014

1. Proteolytic activity within the small intestine of unsuckled calves less than 20 hr of age, anaesthetized with sodium pentobarbitone, has been assessed from the break‐down of [131I]bovine serum γ‐globulin infused into the duodenum.2. Absorption of [131I]γ‐globulin was measured by analysis of venous blood, the levels of radioactivity attained in which were comparable with those when [131I]PVP K.60 (mean mol.wt. 160,000) was administered. When lymph collected from the thoracic duct during the absorption of [131I]γ‐globulin was injected into the femoral vein, the levels of radioactivity in the blood were close to those expected if the labelled material in the lymph had been retained within the plasma. These observations suggested that [131I]γ‐globulin was absorbed into the circulation of the anaesthetized young calf without significant break‐down.3. Gel‐filtration of lymph and plasma from calves fed [131I]γ‐globulin has confirmed that proteolysis before and during absorption was slight, since little 131I labelled material of low mol.wt. was found.4. Gel‐filtration of the contents of the alimentary tract from calves fed [131I]γ‐globulin showed that some hydrolysis occurred in the abomasum and duodenum and that this was reduced by barbiturate anaesthesia. Protein break‐down in the terminal ileum was slight both in the conscious animal and in animals anaesthetized with sodium pentobarbitone.
Changes in the composition of rabbit hind limb lymph after thermal injury
Authors: Lewis G. P. 
Published: December 2014

1. Lymph was collected directly from the hind limbs of rabbits anaesthetized with pentobarbitone and from unanaesthetized rabbits before and for several days after the hind limb was injured.2. After the limb was injured with hot water at 60° C for 1 min or at 80° C for 15–20 sec, there was an increase in the concentration of cytoplasmic and mitochondrial enzymes in the lymph.3. As previously found in cats, it was not until cell destruction was brought about by freezing the limb solid, that there was an increase in the concentration of lysosomal enzymes in the lymph.4. In rabbits which had a cannula permanently implanted in the femoral lymphatic, it was found that the elevated enzyme levels following a 60° C burn returned to normal at between 24 and 36 hr after injury.5. The increase in enzyme activities usually occurred in two phases, an initial increase during the first 4‐6 hr after the burn followed by a second increase which reached a maximum between 10 and 16 hr after injury.6. Even during the second phase which corresponded with the cellular phase of injury there was no increase in lysosomal enzymes.7. The present results support the earlier conclusion that lysosomes take little or no part in the tissue reaction to thermal injury except in the later scavenging processes after cell break‐down.
Effect of calcium on excitatory neuromuscular transmission in the crayfish
Authors: Bracho H. , Orkand R. K. 
Published: December 2014

1. The effects of varying the external Ca concentration from 1·8 to 30 m
M/l. (⅛−2 times normal) have been studied at the in vitro crayfish excitatory neuromuscular junction. Electrophysiological techniques were used to record transmembrane junctional potentials from muscle fibres and extracellular junctional currents from the vicinity of nerve terminals.2. The excitatory junctional potential amplitude was proportional to [Ca]0n, where n varied between 0·68 and 0·94 (mean 0·82) when [Ca]0 was varied from 1·8 to 15 m
M/l.3. The increase in junctional potential amplitude on raising [Ca]0 resulted primarily from an increase in the average number of quanta of excitatory transmitter released from the presynaptic nerve terminal by the nerve impulse.4. The size of the quanta, synaptic delay, presynaptic potential and electrical properties of the muscle membrane were little affected by changes in calcium concentration in the range studied.
The size of rod signals
Authors: Alpern M. , Rushton W. A. H. , Torii S. 
Published: December 2014

1. This investigation is based upon Alpern's (1965) contrast flash observations. The threshold for the test flash λ (Fig. 2a) is raised if a second flash ϕ falls on the annular surround. Moreover, if λ excites rods at threshold, it is only the rods in the surround that contribute to the threshold rise.2. The possibility that the rise in λ threshold might be due to light physically scattered from surround to centre we exclude by several different experiments. We conclude (Fig. 1b) that the ϕ flash sets up a nerve signal N which is conducted to some place C where it inhibits the signal from the centre.3. If the luminous surround, instead of being a full circle (Fig. 2a) consists only of the sectors shown black in Fig. 2b, that occupy 1/m of the surround area, it is found (in the physiological range) that the light/area on those sectors must be m times as great to produce the same threshold rise at centre, i.e. the total surround illumination must remain the same.4. This result would obviously follow if N, the inhibitory nerve signal, were proportional to the total surround illumination. We have established the converse; the signal must be proportional to the quantum catch.5. Light can be increased indefinitely, nerve signals cannot. When ϕ increases sufficiently, N saturates in the same way that S‐potentials and receptor potentials saturate, namely according to N = ϕ/(ϕ + σ) where σ, the semi‐saturation constant is about 200 td sec, or 800 quanta absorbed per rod per flash.6. Thus the nerve signal N is proportional to the quantum catch over 4 log units in the physiological range, namely from 1 quantum per 100 rods to 100 quanta per rod per flash. Above this for another 2 log units N continues to increase, but now more slowly, after the manner of S‐potentials and receptor potentials.
Irreversible impairment of thermoregulation induced by capsaicin and similar pungent substances in rats and guinea‐pigs
Authors: Jancsó-Gábor Aurelia , Szolcsányi J. , Jancsó N. 
Published: December 2014

1. In rats and guinea‐pigs a subcutaneous or intraperitoneal injection of capsaicin, the substance responsible for the pungency of red pepper, produces profound hypothermia associated with skin vasodilatation.2. After large doses of capsaicin rats and guinea‐pigs become insensitive to the hypothermic action of capsaicin. This densensitization is apparently irreversible since it is present months after the capsaicin treatment.3. Capsaicin‐desensitized animals are no longer able to protect themselves against overheating but respond with pronounced hyperthermia to high ambient temperatures (32–40° C). Temperature regulation against cold exposure, however, is not impaired.4. They also respond with an enhanced hyperthermia to painful stimuli such as repeated pinching of the tail or repeated introduction of the thermometer probe into the rectum.5. The enhanced hyperthermias are not due to increased heat production but to impairment of the heat dissipating mechanisms, which in rats and guinea‐pigs acts mainly through evaporation of saliva, and skin vasodilatation.6. Acylamides with pungent action related to capsaicin such as piperine, caprinoyl‐p‐aminophenol and propionyl vanillylamide also cause hypothermia followed by desensitization and their efficacy is dependent on their pungency. The non‐pungent nonenoyl benzylamide produces neither hypothermia nor desensitization.7. Capsaicin and its related pungent acylamides appear first to stimulate and then to desensitize the hypothalamic warmth detectors. By stimulating them the acylamides evoke reflexly the hypothermic response, whereas after desensitization the protective thermoregulatory reflexes for heat dissipation are no longer activated in response to high ambient temperature and to painful stimuli.
Short‐circuit current and ionic fluxes in the isolated colonic mucosa of Bufo arenarum
Authors: Lew V. L. 
Published: December 2014

1. The unidirectional fluxes of 22Na, 36Cl and [14C]bicarbonate ions were measured in paired portions of the isolated and short‐circuited colonic mucosa of Bufo arenarum, separated from its muscular layer. Pharmacological effects as well as effects of changes in the composition of the nutrient solutions on the electrical parameters of membrane activity (potential difference, short‐circuit current and total membrane resistance) are described.2. The net fluxes of both Cl and bicarbonate ions were not significantly different from zero in the absence of electrochemical gradients across the membrane.3. The net Na flux from mucosa to serosa represented a variable proportion of the short‐circuit current ranging from 62 to 100%.4. The proportion of membranes with high discrepancies between net Na flux and short‐circuit current decreased with the duration of captivity of the toads.5. When Na was entirely replaced by choline in the mucosal bathing solution, the short‐circuit current dropped by a variable amount within the range of 64 to 98% of its control values in different membranes. This effect was completely reversible. Similar changes in the serosal solution had no effect.6. The short‐circuit current and potential difference were very sensitive to the serosal concentration of bicarbonate ions. In different membranes, 60–100% of the short‐circuit current was reversibly abolished by bathing the serosal surface with a bicarbonate‐free solution. The mucosal bicarbonate level had no effect on either the potential difference or the short‐circuit current. 5 m
M bicarbonate in the serosal solution restored at least 50% of the short‐circuit control value and full recovery was attained by concentrations near 30 m
M bicarbonate.7. Anoxia brought the potential difference and short‐circuit current reversibly down to zero in about 50 min.8. Ouabain reduced the short‐circuit current up to 80% in about 40 min when present in the serosal solution at a concentration of 10−4
M. At this or lower concentrations the ouabain effect was reversible. Above this level ouabain produced 100% inhibition in 3‐4 hr, but this was no longer reversible. Ouabain had no effect on the short‐circuit current either when applied to the mucosal surface or in the absence of Na from the mucosal solution.9. Diamox produced a variable inhibition of the short‐circuit current of up to 30% only at concentrations above 10 m
M.10. Possible mechanisms are discussed for the appearance of the non‐Na component of the short‐circuit current. A theory concerning its nature is proposed.
Some effects of nerve stimulation and hemicholinium on quantal transmitter release at the mammalian neuromuscular junction
Authors: Jones S. F. , Kwanbunbumpen Suthiwan 
Published: December 2014

1. Rat phrenic nerve—diaphragm preparations have been used to assess some effects of prolonged nerve stimulation on transmitter release.2. The amplitude of the end‐plate potentials evoked by prolonged repetitive nerve stimulation fell gradually during stimulation. Most of this fall was due to a reduction in the number of transmitter quanta released by each nerve impulse; however there was also a small reduction in the muscle cell depolarization produced by each quantum of transmitter.3. Repetitive nerve stimulation also produced a small reduction in the amplitude of the miniature end‐plate potentials. Recovery of amplitude occurred within about 7–8 min of ceasing stimulation.4. A much greater reduction in miniature end‐plate potential amplitude accompanied prolonged nerve stimulation if hemicholinium was present in the bathing solution.5. Estimates of the ‘readily available transmitter’ (Elmqvist & Quastel, 1965b) were made at intervals following prolonged nerve stimulation. Readily available transmitter was reduced, and recovered over approximately 15 min.6. The relationship of these changes to the changes in nerve terminal synaptic vesicle numbers and volumes induced by similar prolonged nerve stimulation (Jones & Kwanbunbumpen, 1970) is discussed.
Synaptic connexions of alpha extensor motoneurones with ipsilateral and contralateral cutaneous nerves
Authors: Rosenberg M. E. 
Published: December 2014

1. Synaptic responses of alpha extensor motoneurones to stimulation of cutaneous nerves of the hind limb were recorded from the lumbosacral region in decerebrate and decerebrate‐spinal unanaesthetized cats. Responses to ipsi‐ and contralateral stimulation are compared.2. Usually a single volley in an ipsilateral cutaneous nerve led to an inhibitory post‐synaptic potential while one in a contralateral cutaneous nerve led to an excitatory post‐synaptic potential or to discharge of the cell, thus demonstrating the classical reciprocal innervation pattern. In some cells either ipsilateral or crossed spinal action was of opposite sign to normal.3. Tests using graded stimulation showed the range of myelinated afferents associated with crossed spinal actions to be narrower than that for ipsilateral actions; for the sural nerve the ranges are 1‐6 μ and 1‐9 μ respectively. A substantial proportion of the coarser myelinated afferents do not make connexion with alpha motoneurones on either side of the cord; in the sural nerve this proportion includes the range 10–17 μ.4. Central transmission times for ipsilateral and crossed‐spinal actions were estimated after making systematic allowance for conduction time to the cord in the associated cutaneous afferents. Mean values for inhibitory pathways from ipsilateral cutaneous nerves were about 2 msec, while those for crossed spinal facilitatory pathways were notably greater, 3‐5 msec.5. Crossed spinal actions were more profoundly depressed by anaesthesia than were corresponding ipsilateral actions.6. Interpretation of the results was aided by a separate study of the input to the spinal cord; stimulus strength is related to the diameters of the cutaneous fibres excited and to peripheral conduction time in those fibres.
The attenuation of rod signals by bleachings
Authors: Alpern M. , Rushton W. A. H. , Torii S. 
Published: December 2014

1. Contrast flash technique allows the rod threshold to be measured even when it lies far above the cone threshold. In this way the rod dark adaptation curve after rhodopsin bleaching can be measured over 6 log units.2. By retinal densitometry the regeneration of rhodopsin can be measured in the same subject. It is found that the log threshold is raised 1·2 units for each 10% of rhodopsin in the bleached state.3. We have tried to discover whether bleaching raises the threshold by desensitizing the rods, or (like backgrounds) by attenuating their signals. Neither suggestion satisfies all conditions.4. All are satisfied by [Formula: see text], where N is the size of rod signal, constant for threshold; θ, θD are steady backgrounds of light and receptor noise; ϕ is the threshold flash with σ a constant of about 2·5 log td sec; B the fraction of pigment in the bleached state.