bluuebunny/crossref_metadata_2025_split huggingface dataset:
The interactions of fibrinogen and dextrans with erythrocytes
Authors: Rampling M. , Sirs John A. 
Published: December 2014

1. The rate of packing of erythrocytes in whole blood, under a centrifugal field of 200 g, has been studied using an automatic recording centrifuge.2. Reduction of the supernatant fibrinogen concentration, by repeatedly washing the cells, lowers the rate of packing and reduces the cell flexibility.3. Resuspending the cells in their own plasma or in isotonic solutions containing fibrinogen restores their flexibility.4. Rouleaux formation has been shown to have no effect on the rate of packing by comparison of blood diluted with plasma, isotonic NaCl or Ringer—Locke solutions. While the degree of rouleaux formation varied with the diluent used, the rate of packing and packed cell haematocrit were the same, for the same dilution.5. Both formalin and dextran altered the degree of rouleaux formation and reduced erythrocyte flexibility. Dextran was found to act indirectly on the erythrocyte flexibility by reducing the plasma fibrinogen concentration.
Release of transmitters on stimulation of the nucleus linearis raphe in the cat
Authors: Ashkenazi Ruth , Holman R. B. , Vogt Marthe 
Published: December 2014

The nucleus linearis intermedius raphe and the nucleus linearis rostralis were stimulated during the perfusion of the anterior horn of the right lateral ventricle of anaesthetized cats. Whereas release of 5‐hydroxytryptamine (5‐HT) was consistently obtained, there was no release of acetylcholine (ACh).The independence of the release of 5‐HT from that of ACh was seen both during low basal release of ACh (rising base line), and during the period when a plateau of resting release had been reached. It was also demonstrated in experiments in which the same perfusate was examined for both compounds.
Direct intracellular pH measurement in rat and crab muscle
Authors: Paillard Michel 
Published: December 2014

1. Conflicting values of intracellular pH (pHi) were obtained by Caldwell in crab muscle and by Carter et al. in rat muscle. To investigate this discrepancy, double and single barrelled pH sensitive micro‐electrodes as described by Carter et al. were used both in rat muscle (in vivo and in vitro) and in large single fibres of crab (in vitro).2. The pHi values obtained in the superficial layers of muscle cells in rat and pHi values obtained in the superficial area of large single fibres in crab seemed in agreement with the Donnan equilibrium. Furthermore, when the membrane potential (Em) value of extracellular pH (pHe) value was changed, each new pHi value was obtained instantly.3. The pHi values obtained in deep layers of muscle cells in rat (pHi 6·68) and in a deep area of large single fibres in crab (pHi 6·96) did not agree with Donnan equilibrium; these pHi values were little influenced by modifications in Em or pHe values.4. These findings could be easily explained if the length of the sensitive portion of the pH micro‐electrode exceeds the diameter of rat muscle cells and is smaller than the diameter of crab large fibres. The pHi values obtained superficially in the two preparations and which seem in agreement with the Donnan equilibrium are artificially low because the Em values recorded by the pH micro‐electrodes are partly shunted.
The effect of previous dietary intake of calcium on calcium absorption in rats
Authors: Kemm J. R. 
Published: December 2014

1. The effects are described of the calcium content of diets with a calcium: phosphate ratio of 1 fed to rats during the preceding 6 weeks on aspects of calcium and phosphate metabolism during the seventh week. The apparent absorption of calcium and phosphate, the urinary excretion of calcium and phosphate, the amounts of calcium and phosphate in the carcass and the fasting serum calcium were studied.2. Apparent absorption of calcium and phosphate decreases the longer an animal is on a high calcium diet and the more calcium there is in that diet. Under the same conditions urinary excretion of calcium is increased while urinary excretion of phosphate remains constant.3. The percentage of calcium and phosphate in the carcass is greater the longer an animal is on a high calcium diet and the more calcium there is in the diet, but dietary changes do not affect the serum calcium.4. Apparent absorption of calcium is not correlated with serum calcium but is significantly correlated with percent carcass calcium.5. A distinction is drawn between the effect of the diet currently being consumed (kinetic effect) and the effect of the diet consumed previously (adaptation).6. Changes in apparent absorption of calcium have a greater effect on calcium retention than on changes in urinary excretion.7. The mechanism bringing about the changes in absorption is discussed and it is concluded that serum calcium is unlikely to be the monitored parameter which detects the need for greater absorption; parathyroid hormone is probably not involved.
The dependence of the latency relaxation on sarcomere length and other characteristics of isolated muscle fibres
Authors: Mulieri Louis A. 
Published: December 2014

1. The latency relaxation has been examined in single fibres from frog striated muscle with particular attention given to its possible relation to Ca2+ release during excitation—contraction coupling.2. Latency relaxations were recorded at 19–23° C from massively stimulated (0·2 msec pulses) single fibres using two selected RCA 5734 transducer tubes in a bridge circuit.3. The depth of the latency relaxation has its full value when stimulus strength is between 40 and 400% above twitch threshold. Stronger stimuli reversibly diminish the latency relaxation.4. The variation in depth of latency relaxation with sarcomere length was found similar to that reported previously for multifibre preparations but in single fibres the peak of the curve consists of a plateau between sarcomere lengths of 2·8 μ and 3·2 μ.5. Sucrose hypertonicity increases the depth of the latency relaxation at sarcomere lengths below 2·8 μ but above this length it has either no effect or a depressant effect depending on the degree of hypertonicity.6. The maximal depth of the latency relaxation (measured at 3 μ) averaged 0·23% of the maximal tetanus tension (measured at 2·2 μ) and was strongly correlated (r = 0·87) with the latter in forty‐five single fibres.7. The maximal depth of the latency relaxation is not correlated with the number of sarcomeres in series in a fibre.8. The results of this study are shown to fully support and extend Sandow's (1966) hypothesis that the latency relaxation is caused by release of activator Ca2+ from the sarcoplasmic reticulum.
Factors affecting the maturation of glomerular filtration rate and renal plasma flow in the new‐born dog
Authors: Kleinman Leonard I. , Lubbe Ronald J. 
Published: December 2014

1. The maturation of glomerular filtration rate was studied by comparison of thirty‐six new‐born mongrel dogs aged 1–35 days with six adult dogs.2. Under mannitol diuresis, glomerular filtration rate (GFR) rose from 0·16 ml. min−1.g kidney−1 at 1 day of age to 0·34 ml. min−1.g kidney−1 at 1 month of age. Adult GFR averaged 0·68 ml. min−1.g−1. There was good correlation of GFR with arterial blood pressure (r = 0·76, P < 0·001). Part of the statistical correlation of GFR with blood pressure was found to be independent of the relationship between blood pressure and age.3. Acute increases or decreases in blood pressure resulted in parallel changes in GFR in the puppies. There was no change of GFR with change of blood pressure in adult dogs. Carotid artery clamping, independent of blood pressure changes, produced increased renal vascular resistance and decreased GFR in the pups.4. Renal plasma flow (RPF) increased from 0·70 ml. min−1.g−1 at 1 day of age to 1·80 ml. min−1.g−1 at 1 month and showed good correlation with blood pressure (r = 0·67, P < 0·001). Filtration fraction (GFR/RPF) and renal vascular resistance did not vary with age in the pup and were the same as those for the adult.5. These results support the hypothesis that maturation of GFR and RPF are closely related to maturation of arterial blood pressure in the mongrel dog. The factors other than blood pressure which also affect renal maturation in the dog still need to be more clearly defined.
Factors affecting the maturation of renal PAH extraction in the new‐born dog
Authors: Kleinman Leonard I. , Lubbe Ronald J. 
Published: December 2014

1. The maturation of renal para‐amino‐hippurate extraction (EPAH) was studied in thirty‐nine mongrel new‐born dogs aged 2–29 days. EPAH was also measured in five adult dogs for comparison.2. There was no apparent change of PAH extraction during the first month of life but EPAH was lower in the puppy than in the adult. Under mannitol diuresis EPAH averaged 0·49 for the puppies and 0·83 for the adult dogs (P < 0·001). EPAH averaged 0·48 for the puppies under nondiuretic conditions, a value not significantly different from that observed during mannitol diuresis. There was no correlation of EPAH with mean arterial blood pressure.3. Inulin extraction (EIn) remained constant during the first month of life and was the same in the new‐born and adult dog suggesting that preglomerular shunting of plasma away from functioning nephrons was the same for both the puppy and adult dog.4. EPAH did not change in the puppy when plasma concentrations varied from trace (using [3H]PAH) to 0·25 m
M indicating that excessive PAH load is not a factor in the low EPAH of the puppy.5. Diffusion of PAH from the red blood cell was excluded as an explanation for the low EPAH since diffusion was the same for both the adult and new‐born dog.
The time course of potassium contracture of single muscle fibres
Authors: Caputo Carlo 
Published: December 2014

1. At 3° C the long duration of potassium contractures and the delay in the repriming process allow one to carry out solution changes while the responses are still in progress, making it possible to study the processes that determine the contracture time course.2. The contractures can be cut short by suddenly lowering the external potassium concentration to normal values. Re‐exposure to the high potassium medium causes the fibres to redevelop tension, in a way that depends on the time at which the original response was interrupted.3. The period of interruption can be prolonged beyond the duration of the original contracture without affecting the second response. This redevelopment of tension is not associated with repriming since this process is much delayed. For thirty‐five interrupted contractures the mean of the sum of the time integrals of tension in the two responses amounts to 98% of the mean of the time integral of tension in the uninterrupted contractures.4. Addition of tetracaine or removal of calcium also causes the fibre to relax from a potassium contracture, although at a slower rate than that obtained by lowering the external potassium concentration. In these cases, however, no tension is redeveloped when the standard contracture medium is reapplied. When calcium in the contracture medium is replaced by nickel, the contracture time course is not diminished.5. The results obtained with potassium contractures clearly show that the contractile activator is released continuously during a contracture. The prolonged time course of contractile responses in the cold can be explained at least in part by a prolonged release of calcium. There are no reasons to believe that at low temperature there is more activator available for release, and therefore it can be concluded that in the cold release of calcium proceeds at a slower rate.6. Release of calcium is under control of the membrane potential, and its time course can be determined either by a fixed store of available calcium that is depleted or by a membrane mechanism which is activated upon depolarization and later inactivates with time. The evidence obtained in the present work does not allow one to decide in favour of one of these two possibilities. However, the fact that contractures are prolonged in the cold, and the finding that repriming is delayed, can be utilized in further studies to clarify the mechanism that controls the release of calcium.
Sodium dependence of the inward spread of activation in isolated twitch muscle fibres of the frog
Authors: Bezanilla F. , Caputo C. , Gonzalez‐Serratos H. , Venosa R. A. 
Published: December 2014

1. The excitatory process travelling along the T‐system may be either electrotonic or regenerative. If Na+ dependent action potential is present in the tubular membranes, high frequency of stimulation might cause a Na+ depletion in the tubules sufficient to abolish this process.2. We tested this hypothesis by recording tension in isolated muscle fibres stimulated tetanically (up to 60 shocks/sec). In low [Na+] solutions, output tension was initially similar to that in normal Ringer, but then fell smoothly to a substantially lower value.3. The activity of individual myofibrils was recorded directly with ciné‐micrographs during isotonic contractions while the fibres were stimulated at high frequencies. In low [Na+]o wavy myofibrils appeared in the centre of the fibre and spread towards the periphery, indicating failure of activation. Wavy myofibrils never appeared in normal Ringer.4. Intracellular action potentials recorded during the tetanic stimulation indicated that the inactivated myofibrils present in low [Na+] solutions cannot be explained by the changes in size and duration of the action potential.5. Our results strongly suggest the existence of a regenerative Na+ conductance in the tubular membrane during the inward spread of an excitatory process.
Transport of calcium in the perfused submandibular gland of the cat
Authors: Nielsen S. Pors , Petersen O. H. 
Published: December 2014

1. In the perfused cat submandibular gland efflux and influx of 45Ca, and concentrations of K, 40Ca and Mg in the effluent from the gland were measured under different experimental conditions.2. When the standard perfusion fluid was shifted to a high Mg (5 m
M) or a low Ca (0·25 m
M) solution the efflux of 45Ca from the pre‐labelled gland declined. The magnitude and the duration of the effect of the high Mg concentration was more marked at a low external Ca concentration and was abolished by Mersalyl (1 m
M). When the standard perfusion fluid was shifted to a Mg‐free solution the efflux of 45Ca from the pre‐labelled gland increased.3. After shift of 45Ca containing perfusion fluid from normal to a high Mg (5 m
M) solution the influx of 45Ca to the gland increased rapidly.4. Both acetylcholine (ACh) and adrenaline caused a marked increase in the efflux of 45Ca from the pre‐labelled gland. This increase in efflux was also seen under conditions where the gland was unable to secrete, i.e. during perfusion with Ca‐free and Na‐free tetraethylammonium Locke solutions.5. Stimulation with ACh failed to reveal any rapidly occurring increase in influx of 45Ca.6. Stimulation with ACh evoked a small temporary increase in the concentration of 40Ca. and Mg in the effluent.7. It is suggested that Ca uptake by intracellular Ca‐accumulating systems of the submandibular gland depends on the external Mg concentration and that ACh and adrenaline cause a release of Ca bound intracellularly.
Heat production and fluorescence changes of toad sartorius muscle during aerobic recovery after a short tetanus
Authors: Becker Anne Godfraind‐De 
Published: December 2014

1. The time course of the aerobic recovery following a 0·5 sec tetanus at 20° C of the sartorius muscle of the toad Bufo bufo, equilibrated in bicarbonate‐CO2 Ringer solution, has been followed by recording simultaneously the heat production and the fluorescence excited by ultra‐violet light at 366 nm.2. The fluorescence light emitted in these conditions in the region of 450 nm monitors the state of oxidation‐reduction of the nicotinamideadenine dinucleotides (NAD+‐NADH). After a short tetanus, the cycle evoked consists of an initial increase of the fluorescence (reduction of NAD+) followed by a long lasting phase of decreased light emission. This includes an early period of oxidation of NADH succeeded by a slow reduction of the NAD+ formed in excess over the resting state. After iodoacetate, the initial reduction is suppressed.3. The time course of both fluorescence and heat production may be analysed into a rapid and a slow component by a double exponential model.4. The time courses of the aerobic recovery heat and of the fluorescence changes are similar after five minutes, but differ in their fast components. IAA significantly increases the rate constants of the fast terms of both monitors.5. The slow component is mainly related to aerobic processes while the fast one is due to both oxidative and glycolytic reactions occurring simultaneously.
The effects of anaesthetics on synaptic excitation and inhibition in the olfactory bulb
Authors: Nicoll Roger A. 
Published: December 2014

1. The effects of anaesthetics (pentobarbitone, hexobarbitone, halothane, urethane, chloralose, chloral hydrate and ethanol) on the extracellular field potentials of the olfactory bulb produced by lateral olfactory tract stimulation were analysed.2. Relatively large doses of all the anaesthetics (e.g. pentobarbitone, 40–70 mg/kg) depressed the synaptic excitation of granule cells.3. The antidromic invasion of mitral cell dendrites was only slightly less sensitive to the anaesthetics than was the synaptic excitation of granule cells.4. A wide dose range of anaesthetics (e.g. pentobarbitone, 3–60 mg/kg) prolonged the granule cell post‐synaptic inhibition of mitral cells. All the anaesthetics, except ethanol, prolonged the inhibition.5. The action of anaesthetics on post‐synaptic inhibition was due to a specific effect on the inhibitory synapses.6. Amino‐oxyacetic acid, an inhibitor of GABA catabolism, had little effect on the synaptic inhibition or on the ability of hexobarbital to prolong the inhibition. This suggests that the prolongation seen with anaesthetics is not a result of interfering with GABA catabolism.7. The present results are compared with results obtained with anaesthetics in other areas of the nervous system and it is proposed that prolongation of ‘gaba‐ergic’ inhibition might contribute to an agent's ability to produce general anaesthesia.
An investigation of spontaneous potentials recorded from the smooth‐muscle cells of the guinea‐pig seminal vesicle
Authors: Kajimoto N. , Kirpekar S. M. , Wakade A. R. 
Published: December 2014

1. A spontaneous discharge of small potentials from smooth muscle cells of the guinea‐pig seminal vesicle has been described. The mean amplitude, frequency and duration of the potentials were 0·9 mV, 12·2/min, and 92 msec, respectively. Occasionally, large potentials of 5–7 mV were recorded.2. The frequency of spontaneous potentials was enhanced by about twofold in 15 m
M potassium—Krebs solution. Removal of calcium from the perfusing solution, or adding excess magnesium (12 m
M) suppressed the rate of these potentials. Cobalt (2·5 m
M) did not affect them but blocked excitatory junction potentials evoked by the hypogastric nerve stimulation.3. The spontaneous potentials were unaffected by atropine. Their rate and amplitude were reversibly reduced in the presence of high concentrations of phentolamine (10−4 but not by 10−5 g/ml.). Guanethidine enhanced the frequency initially (5 min), but subsequently the control rate was not appreciably changed, even after 20 min of guanethidine perfusion.4. After post‐ganglionic denervation or reserpine treatment, the frequency of discharge of spontaneous potentials was reduced, without any effect on amplitude.5. The properties of the spontaneous potentials recorded from the smooth muscle cells of the seminal vesicle are similar to those reported for the vas deferens. They appear to be due to an interaction between noradrenaline released from sympathetic nerve endings and the smooth‐muscle cell membrane. Present experiments cannot completely rule out the possibility that another transmitter in addition to noradrenaline may be released at this neuroaffector junction.
The heat of shortening during repeated tetanic contractions of muscle treated with 1‐fluoro‐2,4‐dinitrobenzene
Authors: Lebacq J. 
Published: December 2014

1. The effect of repeated stimulation and of FDNB on the heat of shortening has been studied in sartorius muscles of Rana temporaria at 0° C.2. The muscles were stimulated at 15 min intervals during 1·2 sec. During the plateau of tetanic activity, they were allowed to shorten 4·3 mm at constant velocity. After eight such contractions, they were poisoned with 0·4 m
M‐FDNB and the series continued.3. From tetanus to tetanus, the tension during shortening decreased faster than the isometric tension; FDNB enhanced this effect. Despite a progressive decrease in the initial heat production, the heat of shortening did not change significantly in the normal muscle; immediately after poisoning it became larger, but from then on, it declined rapidly from tetanus to tetanus, faster than the over‐all heat production.4. The first tetanus after FDNB is thus especially favourable when looking for a chemical counterpart of heat of shortening. On the other hand, the postulated development of a friction in the intoxicated muscle cannot explain the changes in mechanical and thermal properties of the muscle. This point is discussed.
Potassium ion accumulation near a pace‐making cell of Aplysia
Authors: Eaton D. C. 
Published: December 2014

1. A delayed current decrease associated with prolonged depolarization was studied in R15 (the parabolic burster) of Aplysia by using intracellular recording and voltage clamp techniques.2. For long duration command pulses (3 sec), the outward current shows a delayed decrease. The current goes from a maximum near 100 msec and falls until a steady‐state outward current is reached between 1·5 and 2·5 sec after the beginning of the command step. This final steady‐state current is usually only about 20–30% of the peak outward current.3. Double step voltage clamps show that this current decrease is associated with a large shift of e.m.f. Measurements of conductance, on the other hand, fail to show any significant difference in conductance associated with peak and steady‐state currents.4. From the results of application of high K+ ringer, the conclusion is reached that this shift in e.m.f. is due to an accumulation of K+ near the exterior cell membrane. Several other experiments exclude the possibility of either metabolic events or compensating conductance changes producing the phenomenon.5. The location of the accumulation is considered on the basis of anatomical studies. It is concluded that the accumulation takes place in the extensive infoldings found in cells like R15. An explanation of the difference in delayed current decrease between pace‐makers and non‐pace‐makers is suggested, since the pace‐makers apparently have more extensive invaginations than the non‐pace‐makers. This suggestion is lent support by measurements of capitance and current density.