bluuebunny/crossref_metadata_2025_split huggingface dataset:
The rate of the ‘root shift’ in eel red cells and eel haemoglobin solutions
Authors: Forster R. E. , Steen J. B. 
Published: December 2014

1. We have measured the rate of the exchange of O2 between eel red blood cells and their suspending fluid in a modified Hartridge—Roughton continuous‐flow rapid‐reaction velocity apparatus using an oxygen electrode to follow the progress of the reaction.2. The half‐times for the uncomplicated oxygenation and deoxygenation reactions in red cells at 24° C were approximately 0·025–0·08 sec.3. The rate of the Root shift in cell suspensions varied widely, depending on the initial condition of the CO2‐bicarbonate buffer system in the suspending fluid, with the rate of oxygenation or deoxygenation of the intracellular haemoglobin as an upper limit.(a) The most rapid Root shift was produced by a change in extracellular PCO2 with minimal contributions from CO2 hydration—dehydration reactions in the suspending fluid or from ion exchanges across the membrane, and had a half‐time as short as 0·040 sec.(b) The slowest Root shift was produced by an increase in the extracellular lactic acid concentration in the absence of any form of CO2 or in the presence of acetazolamide. This process is presumed limited by the rate of H+ or OH− transfer across the membrane and had a half‐time in excess of 10 sec.(c) The Root off‐shift produced by an increase in PCO2 plus a decrease in extracellular pH showed no significant trend as temperature was lowered from 30° to 11° C.(d) The Root on‐shift produced by a decrease in PCO2 and increase in extracellular pH had a half‐time of 3 sec at 30° C, 9 sec at 24° C and 20 sec at 11° C. These changes appeared limited by the uncatalysed rate of extracellular CO2 hydration.4. Root off‐ and on‐shifts in cell haemolysates at 24° C, produced predominantly by changing pH but with unavoidable subsequent readjustments of the CO2‐bicarbonate buffer systems, had an initial rapid phase with half‐times as low as 0·01 sec. However, the curves were not monotonic, although they became so in the presence of carbonic anhydrase, indicating partial rate limitation by CO2 reactions.
Release into the cerebral ventricles of substances with possible transmitter function in the caudate nucleus
Authors: Portig P. J. , Vogt Marthe 
Published: December 2014

1. One caudate nucleus of the anaesthetized cat was superfused by perfusing the anterior horn of one lateral cerebral ventricle. The perfusates were examined for their content in acetylcholine (ACh), dopamine, homovanillic acid (HVA) and 5‐hydroxytryptamine (5‐HT), at rest and after a variety of stimuli.2. When prostigmine was added to the perfusion fluid, ACh appeared in the effluent; its concentration tended to rise in the course of an experiment. Various afferent stimuli, all of which caused evoked responses recorded from the contra‐lateral caudate nucleus, increased the ACh content of the effluent. Effective stimuli were noise and electrical stimulation of afferent nerves or of certain regions of the brain including the ipsi‐lateral substantia nigra.3. The dopamine content of the effluent was extremely low (of the order of 50 pg/min) at rest, but, on occasion, rose sharply when the substantia nigra was stimulated electrically with trains of pulses repeated once every 3 sec. The results were inconsistent.4. Since dopamine in tissue is rapidly transformed enzymically into HVA, the appearance of this acid in the perfusate was examined.5. At rest, HVA was found to appear in the effluent at a rate of 2‐8 ng/min. Its concentration was rapidly depressed by increasing the depth of anaesthesia.6. Stimulation of the substantia nigra for periods of 3 or 4 min caused an increment in the HVA content of the effluent lasting 1 hr or more. It was frequently seen when two points of the substantia nigra were stimulated simultaneously, less regularly with only one stimulating electrode, and rarely if this was placed in the most caudal part of the substantia nigra.7. These results strongly support the view that there is a dopaminergic nigro‐striatal pathway. The following assumption would explain the erratic appearance of dopamine and the long duration of increments in HVA: many of the axons originating in the substantia nigra end either in the putamen or in parts of the caudate nucleus which are far away from the ventricular surface; any dopamine released from these axons will not reach the ventricular surface at all, and HVA will, at best, reach it very slowly.8. Small amounts of 5‐HT appeared in the ventricular perfusate, and the quantity rose after the administration of monoamine oxidase inhibitors. It was not increased by the type of stimuli used in this work to elicit the release of ACh or HVA.
Transvascular fluid balance in the lung
Authors: Lunde P. K. M. , Waaler B. A. 
Published: December 2014

1. The transvascular fluid balance has been studied in isolated blood‐perfused lungs of rabbit and cat. During periods of left atrial pressure (LAp) elevation, changes in preparation weight were measured. In some experiments simultaneous recordings of changes in blood volume, as judged by changes in emitted radioactivity from 51Cr labelled red blood cells, were performed.2. In nine out of eleven experiments, elevation of LAp by 5 mm Hg within a test period of 8 min resulted in new weight stability and thus apparently in the establishment of a new transvascular fluid equilibrium. In five of these eleven experiments weight stability was also obtained on elevation of LAp by 10 mm Hg. When LAp was elevated further, transvascular fluid equilibrium was not obtained, and a continuous and eventually progressive outward flux of fluid occurred.3. In a preparation with the vasculature paralysed by papaverine in order to avoid vasomotor reactions, changes in plasma protein content caused immediate alterations in the weight slopes of the preparations. These alterations were interpreted as being due to changes in transvascular fluid transfer. Again new stable weights were obtained on moderate changes in plasma protein content.4. New weight and transvascular fluid equilibria seemed to be reached as a result of very small transvascular fluxes of fluid. The transvascular fluid balance in the lung may thus be dynamically maintained as a result of such small fluxes of fluid. The Starling hypothesis could account for this balance, provided that a small shift of fluid can cause sufficiently marked alterations in the osmotic and/or hydrostatic pressure gradient across the wall of the exchange vessels.5. The possible role of a small extravascular compartment with a high fluid colloid osmotic pressure is discussed in relation to transvascular fluid balance in the lung.
The effect of prolonged cold exposure on heat production in new‐born rabbits
Authors: Hardman M. J. , Hey E. N. , Hull D. 
Published: December 2014

1. The rates of oxygen consumption and the colonic temperatures were monitored from birth in rabbits delivered by Caesarean section at term. The rates of oxygen consumption at 25 and 36° C rose over the first 12 hr of life.2. Thirty rabbits were kept unfed in an environment of 25° C from birth. Extra oxygen consumption, in response to cold exposure, failed 24–34 hr later. Twenty‐four of these rabbits were allowed to recover in an environment of 36° C. The metabolic response to cold exposure did not return in those kept unfed or given glucose but those fed with rabbit's milk showed significant recovery when re‐exposed to cold 4 or 18 hr later.3. The tissue glyceride content of brown and white adipose tissue and the liver were greatly reduced once the animals failed to respond to cold exposure and no significant rise was detected during the recovery period after a milk feed.4. Another twelve rabbits were kept unfed in an environment of 36° C. These animals showed a poor metabolic response to cold exposure after 48 hr, although their brown adipose tissue was still replete with fat and the blood glucose rose to normal values during cold exposure.5. These results suggest that an increase in oxygen consumption in response to cold exposure can occur even though brown adipose tissue is largely depleted of glyceride provided that an alternative supply of fuel is available. Glucose alone is not an adequate source of energy.
Heat production and chemical change in tortoise muscle
Authors: Walsh T. H. , Woledge R. C. 
Published: December 2014

1. Measurements have been made of heat production and changes in levels of phosphorylcreatine (PC), ATP and lactic acid resulting from contraction of tortoise muscle under anaerobic conditions.2. The only significant chemical change found was a break‐down of PC.3. The amount of heat produced per mole of PC split (−ΔH) was 13·18 ± 1·04 kcal/mole (mean and
S.E. from thirty‐five observations).4. (−ΔH) is probably rather greater in tortoise than in frog muscle. The value of (−ΔH) cannot easily be accounted for by the known processes accompanying PC splitting in either type of muscle.
Functional specializations of the vascular bed of soleus
Authors: Hilton S. M. , Jeffries M. G. , Vrbová G. 
Published: December 2014

1. The venous outflow from the slow soleus muscle, at rest and during exercise, was compared with that of fast muscles. The blood flow through the soleus at rest was found to be, on average, 52 ml./100 g.min, which is about 4 times that of fast muscles.2. On stimulation of soleus through its motor nerve at low frequencies, up to 8/sec, hardly any increase in flow was observed, whereas fast muscles stimulated at the same rates showed a marked increase, the maximal functional hyperaemia being reached at 8/sec. Even when the soleus muscle was stimulated at frequencies of 40/sec the post‐contraction hyperaemia was very small and sometimes absent.3. The relative absence of functional hyperaemia in the soleus does not appear to be due to low vascular tone, for small amounts of acetylcholine, injected close arterially, produced a considerable increase in blood flow. Further, in experiments in which the vascular tone was increased by lumbar sympathetic stimulation, no functional hyperaemia was seen.It is concluded that a contracting soleus does not release in adequate amounts the substance causing functional vasodilatation in fast muscles.4. No vasodilator effect of adrenaline could be demonstrated in soleus, and the vasodilator effect of isoprenaline was much smaller than that seen in fast muscles.5. The vasoconstrictor effect of lumbar sympathetic stimulation on the resistance vessels of soleus was much smaller than the effect seen in fast muscles. However, the responses of the resistance vessels in soleus to close arterial injections of noradrenaline were not very different from those of fast muscles, and it is suggested that the density of the terminal sympathetic innervation of the vessels of soleus differs from that of fast muscles.
Responses of cat retinal ganglion cells to brief flashes of light
Authors: Levick W. R. , Zacks J. L. 
Published: December 2014

1. The responses of cat retinal ganglion cells to brief flashes of light have been illustrated and described with a view to providing material for comparison with psychophysical experiments in the scotopic (rod‐dominated) range of performance.2. There is a minimum response duration of 50–70 msec no matter how brief the flash is made. This duration is reached with stimuli lasting 32 msec or shorter.3. Reducing the background illumination obviously increases the latency of responses to stimuli at 4 times threshold intensity (about 10 msec increment per log. unit decrement) but has no obvious effect on the minimum response duration.4. The relation between intensity and duration of a flash for threshold responses closely resembles that in human psychophysical experiments. The Bunsen—Roscoe law is applicable for flash durations up to 64 msec.5. If equal amounts of energy are delivered in the form of a pair of flashes of varying separation rather than by rectangular pulses, the shape of the response changes more abruptly with the temporal factor.6. Non‐linear performance is apparent for stimuli as weak as 4 times threshold.7. A method is developed for quantitative analysis of individual responses. It is based upon cross‐correlation of the train of impulses with a Gaussian smoothing function and represents local impulse frequency as a smooth function of time. The method also improves the signal‐to‐noise ratio of post‐stimulus time‐histograms of the sum of many responses.8. The measurement of variability of individual responses is the main result of the method; its magnitude indicates that it is a significant new factor limiting temporal resolution with suprathreshold stimuli.
Independent release of oxytocin and vasopressin during parturition in the rabbit
Authors: Haldar Jaya 
Published: December 2014

1. Oxytocin and vasopressin were assayed in samples of blood collected from seven conscious rabbits during parturition.2. Oxytocin was detected in the blood in ten out of fourteen samples collected during the expulsion of one or more foetuses. Four samples contained 6–100 μu./ml., three 100–200 μu./ml. and three 200–500 μu./ml.3. Vasopressin was detected in six blood samples collected during the delivery of foetuses but in only one experiment did the amount exceed that found in the corresponding control sample collected before or after delivery.4. When both hormones were detected in the same blood sample, the ratio of oxytocin to vasopressin varied from 5:1 to at least 26:1.5. It is concluded that, while oxytocin may not be essential for parturition in the rabbit, stretching of the birth canal during the expulsion of foetuses normally acts as a stimulus for the reflex release of oxytocin from the neurohypophysis and that oxytocin is released independently of vasopressin.
The effect of high oxygen tensions on the mechanical properties of rat lungs
Authors: Hurley R. M. , Rosenberg Edith 
Published: December 2014

1. The average mechanical properties of groups of lungs or lung—thorax systems from pathogen‐free rats weighing approximately 200 g were determined. Static pressure—volume curves and resistances to air‐flow were obtained.2. Six series, each of sixteen rats, were studied. Eight experimental rats in each series were exposed to 4 atm O2 (OHP) in a transparent pressure chamber; the other eight rats, which served as controls, were obtained from the breeder at the same time and studied at the same time.3. In four series, the experimental animals were killed 10 min after gasping due to OHP had been definitely established. One series was a control in which experimental animals were exposed to 4 atm of pressure in an atmosphere containing oxygen at a tension of 150 mm Hg for 190 min. The experimental animals in the sixth series were exposed to 4 atm O2 for 2 hr and none of them gasped.4. Gross and histological examination of sixteen rats, eight of which were killed after 10 min of gasping at 4 atm O2, showed that at this stage of intoxication there was no evidence of pulmonary pathology.5. In none of the series studied were the static pressure—volume curves for deflation shifted, i.e. OHP did not affect the elastic properties of the lungs or the alveolar surfactant.6. In two series studied 10 min after gasping behaviour had been established there was a significant decrease of resistance to air‐flow and a shift to the left of the static pressure—volume curve for inflation with air. The rats in both these series were sedated with pentobarbitone and then killed with pentobarbitone injected into the jugular vein.7. The decrease in resistance to air‐flow was interpreted as broncho‐dilatation and a possible mechanism whereby OHP produces broncho‐dilatation is discussed.
Time course of the sodium influx in squid giant axon during a single voltage clamp pulse
Authors: Bezanilla Francisco , Rojas Eduardo , Taylor Robert E. 
Published: December 2014

1. Sodium influx measurements were carried out on internally perfused squid giant axons under conditions of membrane potential control.2. The ratio ‘measured extra sodium influx/calculated ionic influx from the inward current record’ is close to unity and is independent of the duration of the rectangular pulse of membrane potential.3. The variation of the sodium permeability with time during the voltage clamp pulse is obtained by subtracting the sodium influx obtained from the ‘tail’ current record from the measured extra sodium influx.4. Evidence was obtained indicating that the measured change in sodium permeability during a sudden decrease of the membrane potential from its resting level involves two processes, namely, a transient increase in sodium permeability (activation), and a decrease in sodium permeability (inactivation).5. The extra influx of sodium during a voltage clamp pulse is not decreased by raising the internal sodium concentration from 0 to 100 m
M, supporting the validity of the independence principle.
The involvement of phosphatidylserine in adenosine triphosphatase activity of the sodium pump
Authors: Wheeler K. P. , Whittam R. 
Published: December 2014

1. A study has been made to see whether the ATPase of the Na pump is activated by phospholipids.2. Solubilization of a membrane‐containing (microsomal) fraction from ox brain cortex with deoxycholate removed most or all of the ouabain‐inhibited ATPase and p‐nitrophenylphosphatase (pNPPase) activities. Addition of sonicated dispersions of crude commercial samples of phosphatidic acid, phosphatidylinositol or phosphatidylserine stimulated both enzymic activities, but neither phosphatidylcholine nor phosphatidylethanolamine affected them. After partial purification by chromatography, however, definite activation was demonstrated only with that component of crude samples which migrated like phosphatidylserine.3. The ATPase activity dependent on phosphatidylserine was eliminated by removal of Na and K or by addition of ouabain and was substantially inhibited by oligomycin. The corresponding component of pNPPase activity was partially inhibited by ouabain or by removal of most of the K, but was little affected by oligomycin. The phosphatidylserine‐dependent enzyme(s) therefore exhibited properties characteristic of the ATPase of the Na pump.4. Phosphatidylserine dispersions similarly activated both the ATPase and the pNPPase of the particulate enzyme preparations, untreated with deoxycholate.5. The results suggest that the system for active transport of Na and K involves a complex unit of phosphatidylserine and the protein of the ATPase.
The permanence of tissue binding of thyroxine in the rat
Authors: Harland W. A. , Orr J. S. 
Published: December 2014

1. Male rats were given radiothyroxine and after 24 hr, approximately half the blood volume was replaced by exchange transfusion.2. Plasma concentration of radiothyroxine 2 hr after exchange averaged 81·1% of the value before exchange. This compared with a predicted mean of 97·1% assuming a free and rapid exchange of thyroxine throughout the thyroxine distribution space. The difference between the observed and expected value was highly significant.3. The effective exchangeable pool of thyroxine was found to be approximately twice the plasma volume.4. From these and other observations it is suggested that the liver and plasma constitute most of the exchangeable pool of thyroxine.5. This experiment supports a model of thyroxine metabolism which envisages essentially permanent binding of thyroxine by tissues other than the liver.
Paradoxical temperature dependence of Na and K fluxes in human red cells
Authors: Wieth Jens Otto 
Published: December 2014

1. The effect of temperature on passive movements of sodium and potassium through the red cell membrane has been determined in the presence of various monovalent anions.2. Passive sodium and potassium fluxes varied in a complex way with temperature, when the isotonic electrolyte media contained 120 m
M thiocyanate or salicylate. Between 0 and 18° C the fluxes decreased with increasing temperature. Above 18° C the rate of permeation increased when temperature was increased.3. The ability of anions to induce an increased sodium influx at 0° C was gradually intensified through the following sequence of anions:HCO3− < Cl− = Br− < NO3− < I− « SCN− « salicylate.4. It is proposed that the anion induced effects on the cation permeability are secondary to binding of anions to fixed cations in the red cell membrane. The temperature dependence of the cation fluxes is assumed to reflect the binding on anions to fixed charges at temperatures between 0 and 18° C.
Effect of some monovalent anions on chloride and sulphate permeability of human red cells
Authors: Wieth Jens Otto 
Published: December 2014

1. The permeability of human red cells to 36Cl− and to [35S]SO42‐ was studied in the presence of various monovalent anions.2. A maximum decrease of anion permeability was found in a study of the steady‐state exchange of 36Cl in a medium containing 120 m
M salicylate. The exchange had a half‐time of 3 hr at 0° C, a reduction of normal chloride permeability by a factor of 105. The activation energy of chloride exchange decreased from a value of 45 to 22 kcal/mole in the interval between 0 and 10° C. Simultaneous determination of the permeability to potassium and chloride proved that salicylate induced a reversal of the normal selectivity of red cells at 0° C (permeability coefficient PK of 3·5 × 10−9 cm/sec to be compared with a PCl of 2 × 10−9 cm/sec).3. In contradistinction to the slow movement of 36Cl, the exchange of [14C]salicylate was completed within 4 min, when red cells were suspended at 0° C in the salicylate medium.4. A study of the sulphate permeability at 38° C showed that the rate of steady‐state exchange decreased, when chloride was replaced by lyotropic anions other than bromide. The sequence of the permeability decrease was: Cl− = Br− < I− < NO3 < SCN− < salicylate, the same sequence which previously has been shown to increase the permeability to sodium and potassium. The activation energies of sulphate exchange were 32 kcal/mole (chloride medium), and 38 kcal/mole (thiocyanate medium).5. Sufficient data were obtained during the study to demonstrate that when equilibrium has been obtained, there is a good agreement between the values of 36Cl (cell water)/36Cl (extracellular water) and of {[35S]SO4 (cell water)/[35S]SO4 (extracellular water)}½.6. It is concluded that the anion‐induced changes of permeability are due to binding of anions to fixed cationic charges in the red cell membrane.
The range of thermal insulation in the tissues of the new‐born baby
Authors: Hey E. N. , Katz G. 
Published: December 2014

1. Rectal temperature and skin temperatures were measured in twenty‐eight naked babies weighing 1·1–4·5 kg, lying supine in environments of 25–31 °C when air speed was 4‐7 cm/sec. The ratio of external insulation to internal or tissue insulation for the whole body averaged 2·7 but varied inversely with body weight; the ratio was higher than this on the trunk, and five times lower than this on the hand and foot. The mean ratio rose threefold when environmental temperature was increased to 34–35° C.2. Direct measurements of heat flow from the back of a hand placed in a water jacket maintained at 32° C were made in thirty‐three babies. Heat loss averaged 3 kcal/m2.hr.° C at low environmental temperature, but the loss was often rather less than this in the first 24 hr of life. Heat loss from the hand increased three‐ to fourfold, during exposure to an environment of 35° C.3. When babies more than 48 hr old were exposed to an environment of 34–35° C, heat loss from the hand only increased when rectal temperature reached between 36·6 and 37·3° C; a slightly higher rectal temperature was usually reached before heat loss rose in babies less than 24 hr old.4. Similar methods were used to study specific tissue insulation in three babies with congenital defects of the brain who lacked evidence of temperature control. No changes in insulation were detected in these three babies following changes in environmental temperature.5. It is concluded that the range and pattern of control that can be exerted over the specific thermal insulation of the tissues is essentially the same in babies 2‐20 days old as it is in adult life.