A Quantitative Study of the Ionic Basis of Extraneuronal Potential Changes in the Central Nervous System of the Cockroach (Periplaneta Americana L.)

1971 ◽  
Vol 54 (3) ◽  
pp. 757-777
Author(s):  
Y. PICHON ◽  
R B. MORETON ◽  
J. E. TREHERNE
Keyword(s):  
Periplaneta Americana ◽  
Narrow Channel ◽  
Sodium Ions ◽  
Nernst Equation ◽  
In Series ◽  
Intercellular Clefts ◽  
The Central Nervous System ◽  
Solution Bathing ◽  
Ionic Basis ◽  
Perineurial Cells

1. Measurements have been made of the extraneuronal potential changes produced by replacement of sodium ions with other organic and inorganic cations in the solution bathing isolated abdominal connectives. 2. On the basis of the observed extraneuronal potential changes it is possible to arrange monovalent cations in the following sequence of effectiveness: K+ > Rb+ > Cs+ > TEA+ > Na+ > Li+ > choline+ > tris+. 3. It is concluded that the ionic dependence of the extraneuronal potentials is similar to that of a theoretical model system consisting of a perineurial diffusion barrier in series with a long, narrow channel representing the system of intercellular clefts connecting the inwardly facing surface of the perineurium with the extraaxonal fluid. 4. On the basis of this model the effect of high external concentrations of, for example, potassium ions would be to depolarize the outwardly facing perineurial cell membranes. The considerable departure of the observed potentials from the values predicted by the Nernst equation can be accounted for in terms of the short-circuiting effect, due to the finite ionic permeability of the tight junctions between perineurial cells. Qualitative predictions can also be made concerning the rates of movement of potassium and sodium ions in the extracellular system.

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 Kinetics of Sodium Transfer in the Central Nervous System of the Cockroach, Periplaneta Americana L

1961 ◽  
Vol 38 (4) ◽  
pp. 737-746
Author(s):  
J. E. TREHERNE
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Periplaneta Americana ◽  
Slow Phase ◽  
Second Phase ◽  
Sodium Ions ◽  
Rapid Phase ◽  
Fast Phase ◽  
The Central Nervous System ◽  
Sodium Extrusion

1. The exchange of sodium ions in the cockroach central nervous system has been studied by following the escape of 24Na from isolated abdominal nerve cords, single connectives and ganglia. Particular attention was paid to the initial rapid exchanges of sodium. 2. The escape of sodium ions occurred as a two-stage process, an initial rapid phase eventually giving way to a slower exponential phase of sodium loss. The fast phase of efflux was not affected by the presence of 2:4-dinitrophenol, although this poison significantly reduced the second slow phase of sodium extrusion. 3. The initial fast phase is attributed to a rapid diffusion from an extracellular space, demonstrated by 14C-inulin; the second phase is identified as the slower extrusion from the cellular components of the central nervous system.

The Efflux of Sodium Ions from the Last Abdominal Ganglion of the Cockroach, Periplaneta Americana L

1961 ◽  
Vol 38 (4) ◽  
pp. 729-736
Author(s):  
J. E. TREHERNE
Keyword(s):  
Central Nervous System ◽  
Periplaneta Americana ◽  
Physiological Solution ◽  
Abdominal Ganglion ◽  
Sodium Ions ◽  
Free Solution ◽  
Sodium Efflux ◽  
Nerve Sheath ◽  
The Central Nervous System ◽  
Rate Limiting

1. The rate of loss of 24Na from the terminal abdominal ganglion of Periplaneta americana L. has been studied by measuring the decline in radioactivity associated with an isolated preparation maintained in flowing physiological solution. 2. The rate of sodium efflux was substantially reduced in the presence Of 0.2 mM./l. dinitrophenol and in potassium-free solution. 3. The extrusion of 24Na was not significantly affected by the removal of the fibrous and cellular sheath surrounding the ganglion. The rate-limiting process in the efflux of sodium measured in the experiments was not, therefore, the transfer of ions across the nerve sheath, but an extrusion from tissues lying at a deeper level in the central nervous system.

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 The Ultrastructure of the Perineurium in two Insect Species, Carausius Morosus and Periplaneta Americana

1967 ◽  
Vol 2 (1) ◽  
pp. 119-128
Author(s):  
S. H. P. MADDRELL ◽  
J. E. TREHERNE
Keyword(s):  
Connective Tissue ◽  
Periplaneta Americana ◽  
Fluid Transport ◽  
Insect Species ◽  
Carausius Morosus ◽  
Insect Central Nervous System ◽  
Connective Tissue Sheath ◽  
Extracellular Sodium ◽  
Perineurial Cells ◽  
Cellular Layer

The organization of the perineurium in two insect species (Carausius morosus and Periplaneta americana) has been examined with the electron microscope. In both species this cellular layer has been found to possess an extensive system of tortuous channels between the lateral cell walls. These channels are open at the outer margin adjacent to the fibrous connective-tissue sheath, but appear to be closed at the inner margin by regions of septate desmosomes and/or ‘tight’ junctions. There is an increased surface area at the inner margin of the perineurial cells produced by the presence of long inwardly directed flanges. An electron-dense coat has also been identified on the cytoplasmic side of the type II perineurial cell membranes at points of contact with the underlying extracellular system and at the outer surface adjacent to the connective-tissue sheath. This organization of the perineurium is strikingly similar to that observed in a variety of fluid-secreting epithelia and its possible function in fluid transport is discussed in relation to the available evidence on the physiology of the insect central nervous system. It is suggested, contrary to some earlier suppositions, that the perineurium may not be primarily involved in the control of the extracellular sodium level and that this regulation may be effected at a deeper level in the central nervous tissues.

The Mode of Action of the Corpus Cardiacum on the Hind Gut in Periplaneta Americana

1962 ◽  
Vol 39 (3) ◽  
pp. 319-324
Author(s):  
K. G. DAVEY
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Peripheral Nervous System ◽  
Mode Of Action ◽  
Periplaneta Americana ◽  
Corpus Cardiacum ◽  
Corpora Cardiaca ◽  
The Central Nervous System ◽  
Hind Gut

1. Addition of a homogenate of corpora cardiaca to the fluid bathing an isolated hind gut of Periplaneta produces an increase in tonus, amplitude, frequency and co-ordination of contractions. 2. The corpus cardiacum acts by stimulating cells in the upper colon to release an indolalkylamine. 3. This amine acts on the mucles through a peripheral nervous system which can function in isolation from the central nervous system.

scholarly journals Action of Antidiuretic Hormone on the Equivalent Pore Radius at both Surfaces of the Epithelium of the Isolated Toad Skin

1962 ◽  
Vol 46 (1) ◽  
pp. 117-130 ◽  
Author(s):  
Guillermo Whittembury
Keyword(s):  
Epithelial Cells ◽  
Antidiuretic Hormone ◽  
Outer Surface ◽  
Pore Radius ◽  
Model Membrane ◽  
Toad Skin ◽  
Inner Surface ◽  
In Series ◽  
Solution Bathing ◽  
Swelling And Shrinking

A previously described method (1) allows the observation of swelling and shrinking of the epithelial cells of the isolated toad skin, when the solution bathing either the outer or inner side of the skin is modified. Thus, the concentration of probing molecules of graded size, isotonic to the epithelial cells, across each face of the isolated toad skin can be determined. These concentrations have been used for the estimation of the equivalent pore radius at the outer and inner face of the skin epithelium, following the approach of Goldstein and Solomon for red cells (3). An equivalent pore radius of 4.5 A for the outer surface, and one of 7 A for the inner surface have been obtained. Antidiuretic hormone had an effect only when added to the inner side. This effect was only at the outer surface and is interpreted as widening of the 4.5 A pores to about 6.5 A. A model membrane, formed by narrow and wide pores in series, may explain some of the apparent inconsistencies previously observed.

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