Axonal Function and Ionic Regulation in the Central Nervous System of a Phytophagous Insect (Carausius Morosus)

1967 ◽  
Vol 47 (2) ◽  
pp. 235-247
Author(s):  
J. E. TREHERNE ◽  
S. H. P. MADDRELL
Keyword(s):  
Ionic Composition ◽  
Extracellular Fluid ◽  
Extracellular Recording ◽  
Inorganic Ions ◽  
Sodium Ions ◽  
Phytophagous Insect ◽  
High Concentration ◽  
Action Current ◽  
Local Regulation ◽  
The Central Nervous System

1. Experiments vising intracellular and extracellular recording techniques indicate that, despite the specialized ionic composition of the haemolymph, the axons in the nerve cord of Carausius are conventional in that the action current is largely carried by sodium ions. 2. This effect is achieved by an appreciable regulation of the concentrations of inorganic ions in the extracellular fluid bathing the axon surfaces. 3. The extra-axonal regulation does not appear to result from any significant restriction in the accessibility of cations to the general extracellular system, but from a local regulation which appears to maintain a relatively high concentration of sodium ions at the axon surfaces. 4. It is suggested that such a regulation may be achieved by an extrusion of sodium ions from the glial cells into the restricted extra-axonal spaces demonstrated in the electron micrographs of this preparation.

scholarly journals Exchanges of Sodium Ions in the Central Nervous System of Anodonta Cygnea

1969 ◽  
Vol 51 (2) ◽  
pp. 287-296
Author(s):  
DE FOREST MELLON ◽  
J. E. TREHERNE
Keyword(s):  
Extracellular Fluid ◽  
Freshwater Mussel ◽  
Potassium Ions ◽  
Sodium Ions ◽  
Anodonta Cygnea ◽  
Rapid Exchange ◽  
Exponential Decline ◽  
The Central Nervous System ◽  
Stage Process ◽  
Sodium And Potassium

1. The concentrations of sodium and potassium ions have been measured in the blood and tissues of the cerebro-visceral connective of the freshwater mussel Anodonta. It is shown that, despite the relatively low concentration of sodium ions in the blood, a concentration gradient of this cation is maintained between the extracellular fluid and the nerve cells because of the extremely low intracellular concentration of this cation. 2. Experiments using 24Na and 22Na have shown that there is relatively rapid exchange of sodium ions between the blood and the central nervous tissues. 3. The efflux of labelled sodium occurred as a two-stage process, in which an initial fast fraction gives way to a slower exponential decline. The results can be accounted for on the assumption that efllux of sodium ions in the fast fraction, at 0° C., represents the cations contained in the extracellular fluid. This assumption implies that there is little regulation of the over-all concentration of sodium ions in the extracellular fluid. 4. The results are discussed in relation to the available evidence on the structure and electrophysiology of the cerebro-visceral connectives.

The Distribution and Exchange of Inorganic Ions in the Central Nervous System of the Stick Insect Carausius Morosus

1965 ◽  
Vol 42 (1) ◽  
pp. 7-27
Author(s):  
J. E. TREHERNE
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Extracellular Fluid ◽  
Inorganic Ions ◽  
Stick Insect ◽  
Metabolic Inhibitors ◽  
Carausius Morosus ◽  
Intracellular Compartments ◽  
Extra Cellular Fluid ◽  
The Central Nervous System

1. The distribution and exchange of inorganic ions between the central and the haemolymph has been studied in the stick insect, Carausius morosus, by flame photometry and radioactive tracers. 2. The exchanges of labelled ions show rapid and slow components which correspond to extracellular and intracellular compartments within the central nervous system. 3. The uptake of sodium from the haemolymph and its concentration in the extra-cellular fluid is reduced in the presence of metabolic inhibitors. 4. The distribution between haemolymph and extracellular fluid of calcium and magnesium, and also of sodium in poisoned preparations, conforms to a Donnan equilibrium. The distribution of potassium, even in poisoned preparations, does not conform and it is suggested that the activity of this ion may be lower than in free solution. 5. The concentration of magnesium is appreciably greater in the extracellular than in the intracellular compartment. The possible role of magnesium in nervous transmission in this insect is discussed.

scholarly journals A Quantitative Study of Potassium Movements in the Central Nervous System of Periplaneta Americana

1970 ◽  
Vol 53 (1) ◽  
pp. 109-136
Author(s):  
J. E. TREHERNE ◽  
N. J. LANE ◽  
R. B. MORETON ◽  
Y. PICHON
Keyword(s):  
Periplaneta Americana ◽  
Electrical Response ◽  
Ionic Composition ◽  
Inorganic Ions ◽  
Potassium Ions ◽  
Bathing Medium ◽  
Outward Diffusion ◽  
Giant Axons ◽  
Intercellular Clefts ◽  
The Central Nervous System

1. Using the electrical response of giant axons in the isolated abdominal nerve cord of the cockroach, Periplaneta americana, as an indication of the ionic composition of the fluid bathing their surfaces, it has been shown that the movement of potassium ions from the bathing medium to the extra-axonal fluid, following an increase in the external concentration of this cation, involves an appreciable degree of restriction. 2. This effect is associated with an extracellular diffusion potential, which appears to result from the more rapid penetration of potassium relative to the outward diffusion of sodium ions from the extracellular system. 3. It is suggested that the restriction of intercellular diffusion may occur in the region containing tight junctions and separate desmosomes at the inner end of the intercellular clefts which traverse the perineurium. 4. If the connectives are stretched during mounting, a more rapid depolarization of the giant axons is observed. Comparison of the calculated and the experimentally observed half-times for diffusion of potassium ions to the axon surface indicates that in these preparations the rate of movement of inorganic ions from the external medium is largely determined by the extended intercellular diffusion pathway represented by the mesaxon cleft. 5. In de-sheathed preparations penetration of potassium ions is still more rapid, an effect which is postulated to result from damage to the perineurium, and the consequent production of a shorter, intracellular diffusion channel through the glial system.

scholarly journals Epithelial Sodium Transport and Its Control by Aldosterone: The Story of Our Internal Environment Revisited

2015 ◽  
Vol 95 (1) ◽  
pp. 297-340 ◽  
Author(s):  
Bernard C. Rossier ◽  
Michael E. Baker ◽  
Romain A. Studer
Keyword(s):  
Sodium Transport ◽  
Water Conservation ◽  
Ionic Composition ◽  
Basolateral Membrane ◽  
Extracellular Fluid ◽  
High Concentration ◽  
Regulatory Pathways ◽  
Extracellular Milieu ◽  
Epithelial Barriers ◽  
Set Up

Transcription and translation require a high concentration of potassium across the entire tree of life. The conservation of a high intracellular potassium was an absolute requirement for the evolution of life on Earth. This was achieved by the interplay of P- and V-ATPases that can set up electrochemical gradients across the cell membrane, an energetically costly process requiring the synthesis of ATP by F-ATPases. In animals, the control of an extracellular compartment was achieved by the emergence of multicellular organisms able to produce tight epithelial barriers creating a stable extracellular milieu. Finally, the adaptation to a terrestrian environment was achieved by the evolution of distinct regulatory pathways allowing salt and water conservation. In this review we emphasize the critical and dual role of Na+-K+-ATPase in the control of the ionic composition of the extracellular fluid and the renin-angiotensin-aldosterone system (RAAS) in salt and water conservation in vertebrates. The action of aldosterone on transepithelial sodium transport by activation of the epithelial sodium channel (ENaC) at the apical membrane and that of Na+-K+-ATPase at the basolateral membrane may have evolved in lungfish before the emergence of tetrapods. Finally, we discuss the implication of RAAS in the origin of the present pandemia of hypertension and its associated cardiovascular diseases.

scholarly journals Self-buffering capacity of a human sulfatase for central nervous system delivery

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yi Wen ◽  
Nazila Salamat-Miller ◽  
Keethkumar Jain ◽  
Katherine Taylor
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Buffering Capacity ◽  
The Self ◽  
High Concentration ◽  
Formulation Design ◽  
The Central Nervous System ◽  
Therapeutic Enzymes ◽  
Intrathecal Space

AbstractDirect delivery of therapeutic enzymes to the Central Nervous System requires stringent formulation design. Not only should the formulation design consider the delicate balance of existing ions, proteins, and osmolality in the cerebrospinal fluid, it must also provide long term efficacy and stability for the enzyme. One fundamental approach to this predicament is designing formulations with no buffering species. In this study, we report a high concentration, saline-based formulation for a human sulfatase for its delivery into the intrathecal space. A high concentration formulation (≤ 40 mg/mL) was developed through a series of systematic studies that demonstrated the feasibility of a self-buffered formulation for this molecule. The self-buffering capacity phenomenon was found to be a product of both the protein itself and potentially the residual phosphates associated with the protein. To date, the self-buffered formulation for this molecule has been stable for up to 4 years when stored at 5 ± 3 °C, with no changes either in the pH values or other quality attributes of the molecule. The high concentration self-buffered protein formulation was also observed to be stable when exposed to multiple freeze–thaw cycles and was robust during in-use and agitation studies.

Responses to Hypersaline Exposure in the Euryhaline Crayfish PAcifastacus Leniusculus: II. Modulation of Haemocyanin Oxygen Binding In Vitro and In Vivo

1982 ◽  
Vol 99 (1) ◽  
pp. 447-467
Author(s):  
MICHÈLE G. WHEATLY ◽  
B. R. MCMAHON
Keyword(s):  
Salt Effect ◽  
Ionic Composition ◽  
Inorganic Ions ◽  
Pacifastacus Leniusculus ◽  
Oxygen Binding ◽  
Complete Saturation ◽  
O2 Delivery ◽  
O2 Binding

The effect of 48 h of hypersaline exposure (25, 50 and 75% SW) on haemocyanin oxygenation properties in the euryhaline crayfish Pacifastacus leniusculus was investigated in vitro and in vivo. In vitro significant increases in affinity and cooperativity were measured, although the magnitude of the Bohr shift was unaffected. In vitro dialysis of haemolymph against physiological salines of variable ionic composition proved that these changes were only partly attributable to altered levels of haemolymph ions, implicating the existence of modulators other than H+ and inorganic ions, the possible identities of which are discussed. Significant depressions of both pre- and postbranchial oxygen tensions (Pv, Ov, O2 and Pa, Oa, O2) were observed, but O2 delivery was maintained by utilization of the venous reserve and by an increase in haemocyanin O2 affinity. This occurred despite a concomitant acidosis whose effect on O2 affinity was directly opposed by the ‘salt’ effect. Under hypersaline conditions, haemocyanin played an increasingly important role in O2 delivery in vivo. Despite a reduction in the concentration of combined O2 at complete saturation of the pigment (CmaxHCyOHCyO2). indicating lowered haemocyanin concentration, compensatory changes in O2-binding and cardiac output precluded an impairment to O2 transfer. Equilibration at the tissues (Et,Ot,O2) in FW was less effective than at the gills (Eb,Ob,O2 but progressively improved with hypersaline exposure reversing this trend. Although effects of increased salinity on O2 equilibrium characteristics were qualitatively similar in vivo and in vitro, some interesting quantitative differences are discussed.

Sodium and Potassium Fluxes in the Abdominal Nerve Cord of the Cockroach, Periplaneta Americana L

1961 ◽  
Vol 38 (2) ◽  
pp. 315-322
Author(s):  
J. E. TREHERNE
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Nerve Cord ◽  
Periplaneta Americana ◽  
Unit Area ◽  
Potassium Ions ◽  
Sodium Ions ◽  
Nerve Sheath ◽  
The Central Nervous System ◽  
Sodium And Potassium

1. The influx of sodium and potassium ions into the central nervous system of Periplaneta americana has been studied by measuring the increase in radioactivity within the abdominal nerve cord following the injection of 24NA and 42K. into the haemolymph. 2. The calculated influx of sodium ions was approximately 320 mM./l. of nerve cord water/hr. and of potassium ions was 312 mM./l. of nerve cord water/hr. These values are very approximately equivalent to an influx per unit area of nerve cord surface of 13.9 x 10-2 M cm. -2 sec.-1 for sodium and 13.5 x 10-12 M cm. -2 sec.-1 for potassium ions. 3. The relatively rapid influxes of these ions are discussed in relation to the postulated function of the nerve sheath as a diffusion barrier. It is suggested that a dynamic steady state rather than a static impermeability must exist across the sheath surrounding the central nervous system in this insect.

The Effect of Enzymatic Depolymerization of Arterial Mucopolysaccharides on Sodium Ion Content and Vessel Reactivity

1971 ◽  
Vol 40 (4) ◽  
pp. 293-303 ◽  
Author(s):  
G. S. Harris ◽  
W. A. Palmer
Keyword(s):  
Cation Binding ◽  
Sodium Ion ◽  
Sodium Ions ◽  
High Concentration ◽  
Ion Content ◽  
Binding Properties ◽  
Arterial Walls ◽  
Testicular Hyaluronidase ◽  
Enzymatic Depolymerization

1. The presence of mucopolysaccharides within arterial walls may be associated with the high concentration of sodium ions within this tissue. These polyanions are sensitive to enzymatic depolymerization which results in a loss of the cation binding properties of the molecule. 2. In this study testicular hyaluronidase perfused through isolated arterial segments resulted in a decrease in reactivity of the artery to 65% that of control arteries. Associated with this finding was a 33% decrease in the sodium ion content of the stimulated hyaluronidase-treated artery. When a variety of other sympathetically innervated tissues were treated with hyaluronidase there was no decrease in reactivity or sodium ion content.

Propagation of electrical signals along giant nerve fibres

1952 ◽  
Vol 140 (899) ◽  
pp. 177-183 ◽  
Keyword(s):  
Sea Water ◽  
Giant Axon ◽  
High Concentration ◽  
Nerve Fibres ◽  
Giant Fibre ◽  
Electrical Signals ◽  
Small Fibre ◽  
The Central Nervous System ◽  
Good Conductor ◽  
Ionic Movement

In this part of the discussion we shall attempt to describe the way in which electrical signals are propagated along the giant nerve fibres of squids and cuttlefish. These fibres consist of cylinders of protoplasm, 0.2 to 0.6 mm in diameter, and ire bounded by a thin membrane which acts as a barrier to ionic movement. The protoplasm, or axoplasm as it is commonly called, is an aqueous gel which is a reasonably good conductor of electricity. It contains a high concentration of K + and a low concentration of Na + and Cl - , this situation being the reverse of that in the animal’s blood or sea water. Axons which are left in sea water slowly lose potassium and gain sodium. This process takes about 24 hours and is roughly 80 000 times slower than the diffusion of ions out of a cylinder of gelatin of the same size. The interchange of sodium and potassium is very greatly accelerated by stimulating the fibres. Experiments with tracers, such as those made by Keynes & Lewis (1951) or Rothenberg (1950), allow the interchange to be measured quantitatively, and there is general agreement that the impulse is associated with an entry of 3 to 4 µ µ mol of Na + through 1 cm 2 of membrane and an exit of a corresponding quantity of K + . These quantities are very small compared with the total number of ions inside the fibre. In the giant axon of the squid the quantity of potassium lost in each impulse corresponds to only about 1 millionth if the total internal potassium. One would therefore expect that a giant fibre should be able to carry a great many impulses without recharging its batteries by metabolism. On the other hand, a very small fibre such as a dendrite in the central nervous system should be much more dependent on metabolism since the ratio of surface to volume may be nearly 1000 times greater.

scholarly journals Studying the central control of food intake and obesity in rats

2009 ◽  
Vol 22 (1) ◽  
pp. 163-171 ◽  
Author(s):  
Eliane Beraldi Ribeiro
Keyword(s):  
Genetic Model ◽  
Monosodium Glutamate ◽  
Extracellular Fluid ◽  
Experimental Models ◽  
Central Control ◽  
Physiological Control ◽  
Potential Applications ◽  
The Central Nervous System ◽  
Immunoblot Technique ◽  
Feeding Control

The central nervous system regulates energy intake and expenditure through a complex network of neurotransmitters and neuromodulators. It is of great interest to understand the relevance of these systems to the physiological control of energy balance and to the disturbances of obesity. The present paper discusses some of the methods to address this field used at the laboratory of Endocrine Physiology of Universidade Federal de São Paulo. Initially, different experimental models of rat obesity are presented, namely the hypothalamic induced monosodium glutamate model, the Zucker genetic model, and the dietary model. The principles of brain microdialysis are also presented, the technique applied to obtain representative samples of the extracellular fluid of brain sites involved in feeding control. The microdialysate levels of serotonin, an important anorexigenic neurotransmitter, are determined by HPLC with electrochemical detection. The immunoblot technique (Western blot) is used to determine hypothalamic levels of proteins relevant to the anorexigenic effect of serotonin and to analyze the acute activation of the insulin signaling cascade in the hypothalamus. The final section addresses the potential applications of proteomics in the study of the central control of feeding.

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