bluuebunny/crossref_metadata_2025_split huggingface dataset:
Contribution of Net Ion Transfer Mechanisms to Acid-Base Regulation After Exhausting Activity in the Larger Spotted Dogfish (Scyuorhinus Stellaris)
Authors: Holeton George F. , Heisler Norbert 
Published: April 2021

ABSTRACT
Specimens of the larger spotted dogfish (Scyliorhinus stellaris) were electrically stimulated to exhaustion in a closed seawater recirculation system. The production of large quantities of lactic acid by anaerobic metabolism and the resultant efflux of the dissociation products, H+ and lactate, from the white musculature resulted in severe acid-base disturbances and in increases in plasma lactate concentration, the two effects having extremely different time courses. Plasma pH and bicarbonate were maximally depressed 15–30 min after exercise, whereas peak lactate concentrations of up to 30 mm were not attained before 4–8 h after exercise. The acid-base status was restored to normal 10–14 h after exercise, long before the aerobic processing of surplus lactic acid was complete 22–30 h after exercise.
This behaviour can be explained on the basis of an interaction of transfer rates, buffer values and equilibria between intracellular and extracellular compartments with the transient net transfer of surplus H+ ions to the environmental water. About half of the original quantity of H+ was transferred net to the environment via the branchial epithelium during the first 8–10 h, and it was later taken up again at the rate of aerobic lactic acid processing in the metabolism of the fish, whereas a transfer of lactate was not observed at any time during the experiment. As a result, the distribution patterns of H+ and lactate differed from each other and varied with time elapsed after anaerobic exercise, leading to the apparent ‘H+ ion deficit’ which has been observed in the blood of several fish species during lactacidosis.
Net transfer of H+ ions to the environment facilitates rapid normalization of the acid-base status long before the original stress, lactic acid, is removed from the organism and thus represents an effective regulatory mechanism for the defence of the internal milieu in fish.
Lactate and Proton Dynamics in the Rainbow Trout (Salmo Gairdneri)
Authors: Turner Jeffrey D. , Wood Chris M. , Clark Donna 
Published: April 2021

ABSTRACT
Chronically cannulated rainbow trout were subjected to 6 min of severe burst exercise and monitored over a 12 h recovery period. There were short-lived increases in haematocrit, haemoglobin, plasma protein, Na+ and Cl− levels. Plasma [Cl−] later declined below normal as organic anions accumulated. A much larger and more prolonged elevation in plasma [K+] probably resulted from intracellular acidosis. An intense extracellular acidosis was initially of equal respiratory (i.e. ) and metabolic (i.e. ) origin. However was rapidly corrected while the metabolic component persisted. Plasma ammonia increases had negligible influence on acid-base status. Elevations in blood lactate (ΔLa−) were equal to immediately post-exercise but later rose to twice the latter. Simultaneous white muscle biopsies and blood samples demonstrated that muscle to blood gradients of lactate and pyruvate were maximal immediately post-exercise. As blood levels rose and muscle levels declined, an approximate equilibrium was reached after 4 h of recovery. Intra-arterial infusions of lactic acid in resting trout produced a severe but rapidly corrected metabolic acidosis. The rates of disappearance of and ΔLa− from the blood were equal. Infusions of similar amounts of sodium lactate produced a small, prolonged metabolic alkalosis with a much slower ΔLa− disappearance rate. It is suggested that the excess of ΔLa− over in the blood after exercise is associated with differential release rates of the two species from white muscle rather than differential removal rates from the bloodstream, and that the majority of the lactic acid load in muscle is removed by metabolism in situ.
Studies on The Plasma Colloid Osmotic Pressure of The River Lamprey, Lampetra Fluviatilis, L
Authors: Mcvicar A. J. , Rankin J. C. 
Published: April 2021

ABSTRACT
Values for the total plasma protein concentration of different teleost species range from 3·5–7·0 g% (Field, Elvelhjem & Juday, 1943; Fine, Boffa & Drilhon, 1963; Larsson & Lewander, 1972; Hargens, Millard & Johansen, 1974) and this considerable interspecific variation is reflected in values for the plasma colloid osmotic pressure which ranged from 0·87–2·75 kPa (Keys & Hill, 1934; Hargens et al. 1974).
The Mechanism of Intracardiac Shunting in the Lizard Varanus Exanthematicus
Authors: Heisler N. , Neumann P. , Maloiy G. M. O. 
Published: April 2021

ABSTRACT
Intracardiac shunting was studied in unanaesthetized and unrestrained specimens of Varanus exanthematicus by simultaneous injection of radio- actively labelled microspheres (15 μm) into the right and left atria. Lung ventilation was monitored by intratracheal pneumotachography. It was found that intracardiac shunting was not significantly affected by the spontaneously occurring periods of ventilation and apnoea: the right-to-left shunt averaged 29 and 31%, respectively, and the left-to-right shunt was 11% in both conditions. The observed shunting, although rather constant with time and independent of the ventilatory state, varied in different individuals. Anatomical studies and intracardiac pressure measurements revealed that, in spite of crocodilian-like systolic pressure separation between pulmonary and systemic circulation (based on the muscular ridge, ‘Muskelleiste’, between cavum venosum and cavum pulmonale), the cavum venosum is shared by both the pulmonary and the systemic circulation. Intracardiac shunting appears to be mainly due to wash-out of the cavum venosum: blood remaining in this chamber at the end of systole (oxygenated) or at the end of diastole (deoxygenated) is washed into the respective ‘inadequate’ vascular bed during the next half-cycle of heart action. Thus the extent of intracardiac shunting is expected to depend primarily on the volume and the changes in volume of the cavum venosum during the cardiac cycle.
Giant Fibre Activation of Direct Flight Muscles in Drosophila
Authors: Tanouye Mark A. , King David G. 
Published: April 2021

ABSTRACT
Electrical stimuli delivered to the brain were used to activate the giant fibre of Drosophila. The giant fibre drove a prominent wing opening movement. Intracellular microelectrode recordings from direct wing opener muscle fibres showed that giant fibre activation of an anterior pleural muscle, pa3, was responsible for the wing opening movement. The giant fibre drove a slight wing elevation movement. Intracellular recordings from direct wing elevator muscle fibres showed that these muscles were not activated by the giant fibre. It is suggested that giant fibre-driven wing elevation movements were mediated by the tergotrochanter muscle (TTM).
Locomotion in the North American Mink, A Semi-Aquatic Mammal II. the Effect of an Elongate Body on Running Energetics and Gait Patterns
Authors: M. Williams Terrie 
Published: April 2021

ABSTRACT
Oxygen consumption of minks increased non-linearly with running speed over the range of 0·70–6·40 km h−1. A break in the vs speed relationship occurred at approximately 3·94km h−1 and corresponded to the transition from a walking to a half-bounding gait pattern. Incremental transport costs associated with bounding were 36% lower than for walking at similar speeds. The lower energetic cost of bounding was attributed in part to low stride frequencies and in part to spinal flexion. The latter was particularly important in circumventing stride length restrictions associated with the short limbs of these animals. As a result, stride frequency and stride length of these elongate mustelids at the gait transition speed were similar to values predicted for conventionally-shaped mammals.
Eye Movement Dynamics in the Dogfish
Authors: Montgomery J. C. 
Published: April 2021

ABSTRACT
A method is described of obtaining the relationship between electrical stimulation of the abducens nerve and horizontal eye movement in the dogfish. The stump of the Vlth nerve was stimulated intracranially in a fish in which the brain had been removed, but in which the circulation remained intact, and the gills were perfused with sea water. Horizontal rotation of the eye was monitored with an opto-electronic movement detector. Eye rotation was linearly related to stimulus frequency in the 0–20 Hz range, and was maximal at frequencies above 40 Hz. Stimulation of the Vlth nerve, with a pulse train whose frequency was modulated sinusoidally between 0 and 20 Hz, produced sinusoidal eye movements. The frequency response of the system approximates a first order low pass filter with a characteristic frequency of 0·23 Hz, and an additional phase lag equivalent to a time delay of approximately 50 ms.
Control of a Central Pattern Generator By an Identified Modulatory Interneurone in Crustacea I. Modulation of the Pyloric Motor Output
Authors: Nagy F. , Dickinson P. S. 
Published: April 2021

ABSTRACT
In the lobsters Jasus lalandii and Palinurus vulgaris, the rhythmical activity of the pyloric pattern generator of the stomatogastric nervous system is strongly modified by the firing of a single identified interneurone, whose activity we have recorded from the cell body, in vitro.
The cell body of this interneurone, the anterior pyloric modulator (APM), is located in the oesophageal ganglion and sends two axons to the stomatogastric ganglion via the inferior oesophageal nerves, the commissural ganglia, the superior oesophageal nerves and the stomatogastric nerve.
Firing of neurone APM modifies the activity of all the neurones of the pyloric network, including pacemaker and follower neurones. Its effects are both quantitative (increase in the frequency of the rhythm and in the frequency of spikes within cell bursts) and qualitative (modifications in relative efficacies of the synaptic relationships within the pyloric network, which in turn lead to changes in the phase relationships between the discharges of the neurones).
The effects on pyloric activity induced by firing of neurone APM are established slowly (one or two seconds) and are of long duration (ten times the duration of APM’s discharge). These modifications most probably involve muscarinic cholinergic receptors.
APM’s influences on the activity of pyloric neurones appear to be characteristic of a neuromodulatory process and are such that they may be of behavioural significance in the intact animal.
Factors Affecting Lactate and Proton Efflux From Pre-Exercised, Isolated-Perfused Rainbow Trout Trunks
Authors: Turner Jeffrey D. , Wood Chris M. 
Published: April 2021

ABSTRACT
Glycolysis in muscle during the anaerobic component of severe exercise rapidly produces lactate (La−) and metabolic protons in equal amounts, some of which may enter the blood (Krebs, Wood & Alberti, 1975). In vivo experimentation using strenuously exercised fish has yielded two patterns: La− accumulating in blood either in greater or lesser amounts than . It was rare to find both species at the same concentration, as is the usual case in man (Keul, Keppler & Doll, 1967). In the dogfish (Piiper, Meyer & Drees, 1972) and rainbow trout (Turner, Wood & Clark, 1983a) after exercise, ΔLa− in blood greatly exceeded . The opposite discrepancy occurred in the starry flounder (Wood, McMahon & McDonald, 1977), muskellunge (Beggs, Holeton & Crossman, 1980), and flathead sole (Turner, Wood and Hōbe, 1983b), where ΔLa− was consistently lower than These discrepan cies could be caused either by differential removal rates of the two ionic species from the blood space or by differential release rates from the myotome. We have recently argued that the latter is the dominant process (Turner et al. 1983a,b). However, this is extremely difficult to prove with in vivo methodology, as measurements in a single body compartment with periodic sampling give little information about the dynamic equilibrium between production, metabolism and fluxes between compartments. In vitro muscle preparations can be used to overcome many of these difficulties (e.g., Mainwood & Worsley-Brown, 1975; Benadé & Heisler, 1978). Isolated-perfused rainbow trout trunks have been employed to examine the physiology of systemic vascular resistance control (Wood & Shelton, 1975; Wood, 1977) and substrate utilization by muscle (Moen & Klungsoyr, 1981). In the present study, by strenuously exercising intact trout, then rapidly preparing them as isolated-perfused trunks, it was possible to determine net and La− movement from muscle to perfusate during recovery while simultaneously monitoring muscle [La−] by repetitive biopsy.
Occurrence of Resilin in Elastic Structures in the Food-Pump of Reduviid Bugs
Authors: Edwards H. A. 
Published: April 2021

ABSTRACT
Resilin is a naturally occurring rubber. It is extremely efficient, returning almost all the energy stored during its deformation. Resilin was first described by Weis-Fogh (1960), who with Andersen (Andersen & Weis-Fogh, 1964) produced an extensive review covering the identification, physical and chemical properties of the substance. Andersen & Weis-Fogh set out five diagnostic characters for resilin and reported five sites of resilin occurrence: the wing hinge in all insects studied, includingSchistocerca gregaria and Periplaneta americana; tendons in Aeshna cyanea and Calliphora ery-throcephala; the hindleg spring of various fleas; the abdominal spring of Oryctes sp. and Melolontha sp.; and the clypeolabral spring of Schistocerca gregaria. This communication reports the occurrence of resilin in the food-pump of Reduviid bugs and discusses its functional significance.
Pardaxin Produces Sodium Influx in Theteleost Gill-Like Opercular Epithelia
Authors: Primor Naftali 
Published: April 2021

ABSTRACT
Transport by the gill-like opercular epithelium of the teleost, Fundulus heteroclitus, was affected by pardaxin, a protein that is toxic to fish, isolated from the Red Sea flatfish Pardachirus marmoratus. Administration of pardaxin to the mucosal (seawater) side of the isolated short-circuited opercular epithelium, caused a transient stimulation of the active transport of ions (Isc), followed by an inhibition. The Isc stimulation was abolished by ouabain or/and in Na+-free Ringer but not in Cl−-or HCO3−-Ringer. When applied to the serosal (blood) side, pardaxin did not affect the Isc. Pardaxin produced a net transient Na+ current from the mucosal side to the serosal side of 2·2μequivcm−2h−1. It is concluded that this Na+ influx caused the Isc stimulation. The influx is suggested to be the mechanism of pardaxin’s toxicity in fish.
Cl−-Stimulated Adenosine Triphosphatase: Existence, Location and Function
Authors: Gerencser George A. , Lee Soon-Ho 
Published: April 2021

Abstract
The three universally accepted mechanisms of chloride transport across plasma membranes are: (i) sodium-coupled symport; (ii) anion-coupled antiport; and (iii) coupling to primary ion transport through electrical and/or chemical mechanisms. No direct evidence has been provided for primary chloride transport despite numerous reports of cellular, anion-stimulated ATPases and of chloride transport that cannot be accounted for by the three well-accepted chloride transport processes. Anion-stimulated ATPases are of mitochondrial origin and are a ubiquitous property of practically all animal cells. It also appears that there are other subcellular sites of anion-stimulated ATPase activity, especially the plasma membranes. Recent studies have provided indirect evidence (through parallel studies on the same tissue of anion-stimulated ATPase activity and chloride fluxes) which suggests a possible involvement of ATPase in net movement of chloride up its electrochemical gradient across plasma membranes. Further studies are required to substantiate a direct transport function to Cl−-stimulated ATPases located in the plasma membrane.
Paracellular and Transcellular Routes for Water and Solute Movements Across Insect Epithelia
Authors: O’Donnell M. J. , Maddrell S. H. P. 
Published: April 2021

ABSTRACTBecause the frontal area of the intercellular clefts in Malpighian tubules is small, and the osmotic permeability of the cell membranes is large, the route for transepithelial water movement during fluid secretion is transcellular. Water movements appear to be a passive response to osmotic gradients of a few mosmol 1−1 produced in the cells and in the lumen by active ion transport.The excretory functions of Malpighian tubules are discussed in relation to recent analyses of the routes of passive permeation for non-electrolytes. Uncharged molecules smaller than a disaccharide appear to move at significant rates through the cells whereas molecules as large as inulin traverse the epithelium by a paracellular path. In addition there are specific active transport mechanisms for a variety of organic molecules.The routes and mechanisms proposed for water and solute movements are discussed in relation to comparable studies in other epithelia.
Introduction: Trends in Epithelialtransport and Control
Authors: Phillips John , Lewis Simon 
Published: April 2021

ABSTRACT
Osmotic and ionic regulation ultimately depend on epithelial transport mechanisms and their control in most metazoans, although intracellular osmotic adjustments are probably more important in marine osmoconformers. There are a great variety of osmoregulatory organs throughout the animal kingdom and physiological information about many of these is still so incomplete that it seemed inappropriate to attempt a comprehensive review or synthesis of osmoregulation in a small discussion meeting of this type. However, given the general conservative nature of many cellular processes during the course of animal evolution, we might anticipate common protein carrier mechanisms which are organized and controlled in a limited number of ways within most epithelia. A number of such general concepts and models of epithelial transport have developed over the last ten years and these should prove useful in the future when less well studied osmoregulatory organs are investigated. With this in mind, we have included in this volume reports on some of the most intensively studied epithelia having a range of different regulatory functions. These papers will indicate (1) the types of primary and secondary transport mechanisms which are now well established and partially characterized, (2) their typical asymmetrical distribution in epithelia, and (3) cellular processes associated with their regulation. (4) Finally we consider the relative importance and characteristics of the paracellular route for ion and fluid transfer across epithelia.
Responses of Regularly-Firing Aplysia R3-R13 Neurones to Normoxia and Hypoxia
Authors: Coyer Philip E. 
Published: April 2021

ABSTRACT
Exposure of 10 R3-R13 neurones to a 115-min period of hypoxia resulted in depolarization of their membrane potentials (EM) from a mean of −46·9 ± 3·1 to −20·8 ± 4·4mV (S.E.). Intracellular potassium ion activities decreased significantly from 118·9 ± 5·1 to 67·7 ± 8·5 mm-K+. This is equivalent to a change in EK from − 70·9 mV to −54·5 mV, which is insufficient to account for depolarization of approximately 26 mV. During reoxygenation of the saline surrounding the ganglion, there was a continued depolarization of EM to − 11·5 ± 3·2 mV and progressive fall in to 49·2 ± 4·9 mm. Decreases in the membrane slope resistance were also observed in these depolarizing neurones. The depression in resistance remained irreversible for as long as experiments were conducted. Computations of PNa /PK ratios were made using a steady-state calculation. Increases in the PNa/PK ratio from 0·030 to 0·045 were observed during hypoxic depolarization using a modification of the Goldman equation which neglects the contribution of chloride ions. Subsequent depolarization and loss of a’K during reoxygenation elevated this value to 0·183. Whether or not the observed depression of the membrane resistance is linked to a change in either the sodium or potassium ion permeability is unknown. Release of neurotransmitter and related permeability changes cannot be ruled out as an effect of hypoxia.
Haemolymph Concentration and Apparent Permeability in Varying Salinity Conditions of Gammarus Duebeni, Chaetogammarus Marinus and Gammarus Locusta
Authors: Bolt Stephen R. L. 
Published: April 2021

ABSTRACT
Haemolymph and external medium sodium concentrations have been investigated in three euryhaline amphipods, Gammarus duebeni (Lillje-borg), Chaetogammarus marinus (Leach) and Gammarus locusta (Linnaeus). These were subjected to various salinity regimes, including sudden and cycling salinity changes. The apparent permeability to water of these three species was investigated in various salinity regimes using THO as a marker. Of the three species, only G. duebeni demonstrated large and significant changes in apparent permeability to water. The bulk flow into and out of the animals was calculated showing a variation of responses in the three species, G. duebeni exhibiting the smallest bulk flow and G. locusta the largest.
These results were related to the ecology of the three species.
Electrical Potentials from the Regenerating Eye of Strombus
Authors: Gillary Howard L. 
Published: April 2021

ABSTRACT
Following amputation of the eye of Strombus luhuanus, a morphologically equivalent one is regenerated. Early regenerates exhibited a relatively simple, single-peaked electroretinogram (ERG) that progressively matured to display two ‘on’ peaks, a ‘steady state’ during sustained illumination, and repetitive ‘off’ potentials. ERGs of regenerates were dependent on stimulus intensity, wavelength, light adaptation and temperature, as are those of mature eyes. Intracellularly recorded light-evoked depolarizations from retinas of early stages of regeneration tended to be simpler in waveform than those of more mature stages. In addition, certain cells exhibited light-evoked and electrically evoked action potentials, while others were hyperpolarized by light. Optic nerves of eyes in early stages of regeneration showed only ‘on’ activity, while those of later stages also exhibited ‘off’ responses.
Proprioceptive Reflexes Change When an Insect Assumes an Active, Learned Posture
Authors: Zill Sasha N. , Forman Robin R. 
Published: April 2021

ABSTRACT
Imposed changes in activity of a joint angle receptor of the locust leg, the metathoracic femoral chordotonal organ, produce variable, phasic reflex responses in a leg extensor motoneurone in untrained animals. After training the locust to maintain a posture in extension beyond a minimum required joint angle, these reflexes are consistently tonic and excitatory. This plasticity of reflex responsiveness permits the locust to couple motoneurone firing to afferent activity when receptor input is behaviourally relevant.