Studies on Fresh-Water Osmoregulation in the Ammocoete Larva of Lampetra Planeri (Bloch)

1970 ◽  
Vol 52 (2) ◽  
pp. 275-290
Author(s):  
R. MORRIS ◽  
J. M. BULL
Keyword(s):  
Sodium Concentration ◽  
Sodium Balance ◽  
Sodium Influx ◽  
Environmental Concentration ◽  
Carrier Mechanism ◽  
Controlling Mechanism ◽  
Lampetra Planeri ◽  
Reverse Situation ◽  
Sodium Loss ◽  
Term Response

1. Sodium influx in ammocoete larvae increases exponentially with external sodium concentration (0-1.0 mM/l.) and sodium-depleted animals show a 20% increase compared with normal animals. 2. Sodium loss decreases as the environmental concentration decreases, although the reverse situation is expected from considering diffusion outflux alone. 3. It is argued that part of the sodium loss is back-transported by the transport mechanism and this accounts for the reduced sodium loss from sodium-depleted animals whose sodium carrier activity is increased. The curves relating back-transport to environmental sodium differ from those derived by Kirschner for isolated frog skin. 4. Sodium influx increases as sodium loss increases, indicating a self mechanism whose features are discussed. In the ammocoete, the sodium carrier mechanism appears to change in affinity for sodium (short-term response) and can also change in concentration (long-term response), and it is suggested that these features, together with permeability changes, may form the basis of the controlling mechanism for sodium balance.

Studies on Sodium Balance in Gammarus Duebeni Lilljeborg and G. Pulex Pulex (L.)

1961 ◽  
Vol 38 (1) ◽  
pp. 1-15
Author(s):  
J. SHAW ◽  
D. W. SUTCLIFFE
Keyword(s):  
Loss Rate ◽  
Sea Water ◽  
Sodium Concentration ◽  
Sodium Balance ◽  
Nacl Solution ◽  
Uptake Mechanism ◽  
External Concentration ◽  
Sodium Influx ◽  
Low Concentrations ◽  
Sodium Loss

1. The mechanisms of sodium balance in Gammarus duebeni and G. pulex, adapted to various external concentrations, were compared. 2. G. duebeni could be adapted to live in 1 mm/l. NaCl solution and, in some cases, to concentrations down to 0.2 mM/l. G. pulex could survive in concentrations as low as 0.06 mM/l. 3. The sodium loss rate in G. duebeni adapted to 2% sea water was much higher than in G. pulex but was reduced to about the same level when the animals were adapted to low external concentrations. 4. In both species there was a non-linear relationship between sodium influx and the external sodium concentration. In G. duebeni the uptake mechanism was saturated at an external concentration of about 10 mM/l., whereas in G. pulex saturation was reached at a much lower concentration. The maximum rate of uptake was greater in G. duebeni than in G. pulex. 5. In both species adaptation to low concentrations involved a small increase in the sodium influx and a reduction in the loss rate. 6. The most important factor in the superiority of G. pulex over G. duebeni in surviving at low external concentrations is the high affinity for sodium displayed by the uptake mechanism in G. pulex.

Studies on Ionic Regulation in Carcinus Maenas (L.)

1961 ◽  
Vol 38 (1) ◽  
pp. 135-152
Author(s):  
J. SHAW
Keyword(s):  
Body Weight ◽  
Sea Water ◽  
Carcinus Maenas ◽  
Sodium Concentration ◽  
Sodium Balance ◽  
Uptake Mechanism ◽  
Sodium Influx ◽  
Urine Production ◽  
Sodium Loss ◽  
Total Sodium

1. The mechanism of sodium balance in Carcinus maenas has been investigated. 2. Measurements of sodium outflux showed no evidence of a decrease in surface permeability to sodium in dilute sea water. 3. The rate of urine production in normal sea water was 3.6% body weight per day and the sodium loss through the urine was insignificant compared with the total sodium loss. In 40% sea water the urine rate was increased to 30% body weight per day and the loss in the urine accounted for 20% of the total loss. 4. Measurements of sodium influx and calculation of the active component showed that the active uptake mechanism was fully saturated at all external concentrations in which the animals could survive. 5. Regulation of the blood sodium concentration is effected largely by the activation of the sodium uptake mechanism. This prevents the blood concentration falling below a critical level as long as the external concentration itself is not too low.

The Sodium Balance Mechanism in the Fresh-Water Amphipod, Gammarus Lagustris Sars

1967 ◽  
Vol 46 (3) ◽  
pp. 519-528
Author(s):  
D. W. SUTCLIFFE ◽  
J. SHAW
Keyword(s):  
Fresh Water ◽  
Loss Rate ◽  
Sodium Concentration ◽  
The Body ◽  
Sodium Balance ◽  
External Concentration ◽  
Sodium Influx ◽  
Influx Rate ◽  
Sodium Loss ◽  
Balance Mechanism

1. The sodium balance mechanism of Gammarus lacustris in fresh water is virtually identical with that found in G. pulex. 2. The sodium transporting system at the body surface has a very high affinity for sodium ions. The system is half-saturated at an external concentration of about 0.14 mM/l. and fully saturated at about 1 mM/l. sodium. 3. The lowest external concentration at which sodium balance was maintained was 0.06 mM/l. 4. Both the total sodium loss rate and the sodium influx rate remained approximately constant in animals acclimatized to the range of external concentrations from 2 to 0.3 mM/l. NaCl. At lower concentrations the loss rate was reduced and the influx increased by a factor of about 1.5. 5. Changes in the sodium influx and loss rates are very closely linked together, and it is shown how these changes are related to the external sodium concentration.

Sodium Regulation in the Freshwater Mollusc Limnaea Stagnalis (L.) (Gastropoda: Pulmonata)

1970 ◽  
Vol 53 (1) ◽  
pp. 147-163 ◽  
Author(s):  
PETER GREENAWAY
Keyword(s):  
Blood Volume ◽  
Tap Water ◽  
Sodium Concentration ◽  
Sodium Balance ◽  
Uptake Mechanism ◽  
Sodium Influx ◽  
Sodium Uptake ◽  
Limnaea Stagnalis ◽  
Total Body ◽  
Sodium Regulation

1. Sodium regulation in normal, sodium-depleted and blood-depleted snails has been investigated. 2. Limnaea stagnalis has a sodium uptake mechanism with a high affinity for sodium ions, near maximum influx occurring in external sodium concentrations of 1.5-2 mM-Na/l and half maximum influx at 0.25 mM-Na/l. 3. L. stagnalis can maintain sodium balance in media containing 0.025 mM-Na/l. Adaptation to this concentration is achieved mainly by an increased rate of sodium uptake and a fall of 37 % in blood sodium concentration, but also by a reduction of the sodium loss rate and a decrease in blood volume. 4. A loss of 23% of total body sodium is necessary to stimulate increased sodium uptake. This loss causes near maximal stimulation of the sodium uptake mechanism. 5. An experimentally induced reduction of blood volume in L. stagnalis increases sodium uptake to three times the normal level. 6. About 40% of sodium influx from artificial tap water containing 0.35 mM-Na/l into normal snails is due to an exchange component. Similar exchange components of sodium influx were also observed in sodium-depleted and blood-depleted snails in the same external sodium concentration.

Erratum

1970 ◽  
Vol 52 (2) ◽  
pp. 494-494
Keyword(s):  
Fresh Water ◽  
Sodium Transport ◽  
Sodium Concentration ◽  
Sodium Influx ◽  
Lampetra Planeri

MORRIS, R. & BULL, J. M. Studies on fresh water osmoregulation in the Ammocoete larvae of Lampetra planeri Bloch. III. The effect of external and internal sodium concentration on sodium transport. J. Exp. Biol. 52, 2, pp. 275-290. Page 287. Figure 5. For ‘Sodium influx (µM/gm./hr.)’ read ‘Sodium influx (µM/3gm./hr.)’

Studies on Freshwater Osmoregulation in the Ammocoete larva of Lampetra Planeri (Bloch)

1968 ◽  
Vol 48 (3) ◽  
pp. 597-609
Author(s):  
R. MORRIS ◽  
J. M. BULL
Keyword(s):  
Low Temperature ◽  
Extracellular Space ◽  
Ringer Solution ◽  
Temperature Treatment ◽  
Sodium Influx ◽  
Sodium Chloride Solutions ◽  
Low Temperature Treatment ◽  
Lampetra Planeri ◽  
Equilibrium Concentrations ◽  
Sodium Loss

1. An investigation has been made of the factors which cause sodium loss from ammocoetes when they are immersed in de-ionized water at 1° and 10° C. 2. Sodium influx ceases when animals are first immersed in de-ionized water, but can recommence when the animal loses sufficient sodium to the environment. The concentration of sodium required for influx to take place decreases with succeeding periods of immersion in de-ionized water at 10° C. and reaches minimum equilibrium concentrations as low as 0.005 mM-Na/l. 3. Low temperature inhibits sodium influx and thus promotes net loss of sodium to de-ionized water. 4. Low temperature also decreases the initial loss of sodium to de-ionized water and probably lowers the permeability of the external surfaces of the animal to ions. This effect is small compared with the inhibition of ion uptake so that the combined result is to increase the net loss of sodium from the animal. 5. Since animals lose calcium to de-ionized water and show a decreased rate of sodium loss when calcium salts are added, it is believed that the high rates of sodium loss in de-ionized water are attributable to the effect of calcium on permeability. 6. Lack of calcium may also explain why animals which have been depleted of sodium by low-temperature treatment take up sodium much faster at higher temperatures from dilute Ringer solutions than from pure sodium chloride solutions. 7. When animals lose ions to de-ionized water at low temperature, sodium and chloride are lost from the extracellular space, whilst the muscle cells lose potassium. These ions are recovered into the extracellular space when animals are allowed to take up ions at 10° C. from diluted Ringer solution later.

Sodium Regulation in the Fresh-Water Amphipod, Gammarus Pulex (L.)

1967 ◽  
Vol 46 (3) ◽  
pp. 499-518
Author(s):  
D. W. SUTCLIFFE
Keyword(s):  
Fresh Water ◽  
Body Surface ◽  
Loss Rate ◽  
Sodium Concentration ◽  
The Body ◽  
Uptake Mechanism ◽  
Sodium Influx ◽  
Sodium Uptake ◽  
Sodium Loss ◽  
Total Sodium

1. Sodium influx and loss rates in Gammarus pulex were measured at constant temperatures. The sodium loss rate was immediately influenced by a change in temperature, with a Q10 of 1.5 to 2.0 at temperatures between 0.3 and 21.5° C. The sodium influx rate is apparently influenced in the same way. 2. The sodium uptake mechanism in G. pulex from three localities was half-saturated at an external concentration of 0.10-0.15 mM/l. sodium. 3. The total sodium loss rate remained approximately constant in animals acclimatized to the range of external concentrations from 2 to about 0.2 mM/l. sodium. 18% of the sodium was lost in urine with a sodium concentration estimated at 30-50 mM/l. The remainder of the sodium loss was due to diffusion across the body surface. 4. In animals acclimatized to concentrations below about 0.2 mM/l. sodium the sodium loss rate was reduced, due to (a) a lower diffusion rate following a fall in the blood sodium concentration, and (b) the elaboration of a more dilute urine. 5. There was a very close association between changes in the blood sodium concentration, the elaboration of a very dilute urine, and the rate of sodium uptake at the body surface. The results indicate that a fall in the blood sodium concentration leads to simultaneous activation of the sodium uptake mechanisms at the body surface and in the antennary glands. 6. It is estimated that, by producing a dilute urine, total sodium uptake in G. pulex is shared equally between the renal uptake mechanism and the mechanism situated at the body surface. 7. In sea-water media G. pulex drinks and expels fluid from the gut. In a medium slightly hyperosmotic to the normal blood concentration the amount imbibed was equal to the normal rate of urine flow when in fresh water.

The Contribution of Hemofiltration among the Treatment Modalities of Chronic Uremia

1993 ◽  
Vol 16 (12) ◽  
pp. 809-815 ◽  
Author(s):  
E. Vidi ◽  
F. Bianco ◽  
G. Panzetta
Keyword(s):  
Sodium Concentration ◽  
Treatment Modalities ◽  
Sodium Balance ◽  
Efficient Removal ◽  
Treatment Change ◽  
Balance Study ◽  
Plasma Urea ◽  
Fluid Removal ◽  
Before And After ◽  
Sodium Loss

To assess the role of hemofiltration (HF) among different treatment modalities, we reviewed our clinical material from 37 patients that consecutively underwent the treatment from 1981 on. A number of 12 patients on HF for at least 1 year deliberately switched to hemodialysis (HD) or hemodiafiltration (HDF) were studied retrospectively. Biochemical and nutritional parameters, cardiovascular aspects and morbidity data were collected during one year before and after the treatment change. A sodium balance study was perfomed in 9 patients during HF as well. No significant differences in plasma urea, creatinine, phosphate, body weight, serum albumin, transferrin, hemoglobin and PCR were found. BUN tended to be lower during HD-HDF because of the more efficient removal of urea with these treatments. Indeed, the Kt/V index was 0.91 during HF and it was 1.15 with HD-HDF. There were no differences in hypotensive episodes and morbidity. Sodium loss was strictly related to body fluid removal during HF session with a net sodium loss (NSL) of 128 mEq per liter of fluid removal (FR) (NSL = 6.44 + 122 FR; r:0.83; p<0.01). Adapting sodium concentration of substitution fluid to patients weight gain, cardiovascular stability improved in those subjects more prone to collapse. With equivalence in PCR during the 2 periods, although Kt/V was 20% lower during HF, it seems reasonable to assume that the lower urea clearance might be compensated by the more efficient removal of higher molecular weight substances and/or by the improved biocompatibility of HF.

The Effect of Some Anions and Cations Upon the Fluxes and Net Uptake of Sodium in the Larva of Aedes Aegypti (L)

1965 ◽  
Vol 42 (1) ◽  
pp. 29-43 ◽  
Author(s):  
R. H. STOBBART
Keyword(s):  
Sodium Concentration ◽  
Sodium Content ◽  
Deionized Water ◽  
Sodium Balance ◽  
Sodium Influx ◽  
Sodium Uptake ◽  
Chloride Uptake ◽  
Net Uptake ◽  
The Relationship ◽  
Anal Papillae

1. Starved 4th-instar larvae of Aädes aegypti, when put into deionized water at a density of ten larvae/20 ml., are able to achieve sodium balance at the low external concentration of 5µM Na/l. 2. The balancing process involves a 10% drop in total sodium content, a more or less complete activation of the mechanism for sodium transport, and a reduction in the permeability of the larva to sodium as measured by the net sodium loss into deionized water. It is very probable that most of this reduction occurs in the anal papillae. 3. The relationship between external sodium concentration and sodium influx in larvae previously ‘balanced’ in deionized water is described approximately by the Michaelis equation. The sodium outflux also increases with increasing external sodium concentrations. 4. The net uptake of sodium by ‘balanced larvae’ appears to be significantly greater from solutions of NaCl than from solutions of NaNO3 NaHCO3 and Na2SO4. 5. The ions K+ Ca++ Mg++ and NH4+ when present as chlorides stimulate the influx of sodium from 0.1 mM/l. sodium chloride. When present as nitrates or sulphates they either have no effect or cause an inhibition of influx. 6. The results in 4 and 5 suggest that movements of chloride may be important in sodium uptake, and chloride uptake has been found to occur independently of sodium uptake. Measurements of potential difference between haemolymph and medium demonstrate active transport of both sodium and chloride.

The Absorption of Sodium Ions by the Crayfish, Astacus Pallipes Lereboullet

1959 ◽  
Vol 36 (1) ◽  
pp. 126-144 ◽  
Author(s):  
J. SHAW
Keyword(s):  
Uptake Rate ◽  
Equilibrium Concentration ◽  
Maximum Level ◽  
Sodium Concentration ◽  
Sodium Content ◽  
Sodium Balance ◽  
Sodium Ions ◽  
External Concentration ◽  
Sodium Influx ◽  
True Measure

1. The effects of external and internal sodium concentrations on the uptake of sodium ions by the crayfish, Astacus pallipes, has been studied. 2. The normal sodium influx, measured with 24Na, from O.3 mM /l. NaCl solution is 1.5 µM./10 g. body weight/hr. The rate of loss of sodium to de-ionized water has roughly the same value. 3. Net loss of sodium reduces the external sodium concentration required for sodium balance. The minimum equilibrium concentration is about 0.04 mM./l. NaCl. 4. The relation between the external sodium concentration and the sodium influx is non-linear. The influx has a maximum of about 10 µM./10 g./hr. at an external concentration of approx. 1 mM./l. 5. The 24Na influx is a true measure of the sodium uptake rate at low external concentrations. At higher concentrations the influx may exceed the uptake rate by some 20%. 6. Net loss of sodium increases the influx by three to five times. Loss of 5-10% of the total internal sodium increases the influx from the normal to the maximum level. A 1% change has a significant effect on the influx. Changes in the internal sodium content reflect changes of the blood sodium concentration. 7. A scheme is suggested whereby the external and internal sodium concentrations interact together on the influx to produce a self-regulating system which maintains the animal in sodium balance.

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