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.

Sodium Regulation in the Amphipod Gammarus Duebeni From Brackish-Water and Fresh-Water Localities in Britain

1967 ◽  
Vol 46 (3) ◽  
pp. 529-550 ◽  
Author(s):  
D. W. SUTCLIFFE
Keyword(s):  
Fresh Water ◽  
Body Surface ◽  
Brackish Water ◽  
Loss Rate ◽  
Sea Water ◽  
The Body ◽  
Sodium Ions ◽  
Sodium Uptake ◽  
Sodium Loss ◽  
Sodium Regulation

1. A quantitative study of sodium influx and loss rates was made on Gammarus duebeni obtained from brackish-water localities. Both influx and loss rates were immediately doubled by a rise in temperature from 10 to 20° C. 2. It is estimated that when animals are fully acclimatized to a series of media decreasing from 50 to 2% sea water the rate of sodium uptake at the body surface is doubled to balance the rate of sodium loss, which is also doubled. The increased loss rate is due equally to an increase in the rate of diffusion across the body surface and to loss in hypotonic urine containing about 160-190 mM/l. sodium. Diffusion losses normally account for at least 35% of the total losses, even when the urine is isotonic with the blood. 3. The sodium-transporting system at the body surface is fully saturated at an external concentration of about 10 mM/l. NaCl (2% sea water). The system has a low affinity for sodium ions and is only half-saturated at 1.5-2.5 mM/l. sodium. The overall rate of uptake is increased to its maximum rate to balance sodium losses when in fresh water. 4. When acclimatized to fresh water (0.25 mM/l. NaCl) the sodium loss rate is greatly reduced. This was partly due to a lower rate of diffusion across the body surface following a fall in the blood sodium concentration, and mainly due to elaboration of a very dilute urine. 5. It is suggested that increases in sodium uptake in the antennary glands, resulting in a hypotonic urine, are linked with increases in uptake at the body surface. Both uptake systems are possibly activated by a single internal regulator responding to changes in the blood concentration. 6. Sodium regulation at concentrations below 10 mM/l. NaCl was examined in G. duebeni obtained from fresh-water streams on the Lizard peninsula, the Kintyre peninsula, and the Isle of Man. The regulation of sodium uptake and loss is very similar to regulation in brackish-water animals, and the sodium-transporting system has the same low affinity for sodium ions at concentrations below about 10 mM/l. 7. It is suggested that fresh-water localities in north-west Europe, excluding Ireland, have been colonized from brackish water without any modifications in the sodium-regulatory mechanism. But the fresh-water animals tolerate very low sodium concentrations better than brackish-water animals. This is apparently due to natural selection of individuals in which the sodium uptake rate is higher than the average uptake rate in brackish-water animals.

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.

Active Transport and Sodium Fluxes at Moult in the Amphipod, Gammarus Duebeni

1969 ◽  
Vol 51 (3) ◽  
pp. 591-605
Author(s):  
A. P. M. LOCKWOOD ◽  
W. R. H. ANDREWS
Keyword(s):  
Fresh Water ◽  
Body Surface ◽  
Major Part ◽  
Sea Water ◽  
Sucrose Solution ◽  
The Body ◽  
Active Sodium ◽  
Sodium Influx ◽  
Sodium Uptake ◽  
High Level

1. The sodium fluxes of individual Gammarus duebeni, which moulted in sea water, have been followed daily from the morning following moult for at least 6 days. 2. Sodium influx from sea water declined from 15.1µM/animal/hr. on the first morning after moult to 1.7µM/animal/hr. by the tenth day after moult. 3. Sodium influx from 10 mM/l. NaCl plus sucrose solution isotonic with sea water declines from 4.48µM/animal/hr. to 0.14µM/animal/hr. in inter-moult animals. 4. Thionine inhibits over 90% of the influx from 10 mM/l NaCl plus isotonic sucrose on the first day after moult, and this, together with other evidence, suggests that the major part of the influx from this medium is due to active sodium uptake. The rate of active uptake is comparable with, or faster than, the rate of uptake by animals acclimatized to fresh water. 5. The influx occurs primarily across the body surface. It is suggested that the high level of sodium uptake is associated with the water uptake which occurs at moult.

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.

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.

Sodium Regulation and Adaptation to Fresh Water in Gammarid Crustaceans

1968 ◽  
Vol 48 (2) ◽  
pp. 359-380
Author(s):  
D. W. SUTCLIFFE
Keyword(s):  
Body Weight ◽  
Fresh Water ◽  
Body Surface ◽  
Sea Water ◽  
Sodium Concentration ◽  
The Body ◽  
Outward Diffusion ◽  
Gammarus Zaddachi ◽  
Freshwater Habitats ◽  
Sodium Regulation

1. Sodium uptake and loss rates are given for three gammarids acclimatized to media ranging from fresh water to undiluted sea water. 2. In Gammarus zaddachi and G. tigrinus the sodium transporting system at the body surface is half-saturated at an external concentration of about 1 mM/l. and fully saturated at about 10 mM/l. sodium. In Marinogammarus finmarchicus the respective concentrations are six to ten times higher. 3. M. finmarchicus is more permeable to water and salts than G. zaddachi and G. tigrinus. Estimated urine flow rates were equivalent to 6.5% body weight/hr./ osmole gradient at 10°C. in M. finmarchicus and 2.8% body weight/hr./osmole gradient in G. zaddachi. The permeability of the body surface to outward diffusion of sodium was four times higher in M. finmarchicus, but sodium losses across the body surface represent at least 50% of the total losses in both M. finmarchicus and G. zaddachi. 4. Calculations suggest that G. zaddachi produces urine slightly hypotonic to the blood when acclimatized to the range 20% down to 2% sea water. In fresh water the urine sodium concentration is reduced to a very low level. 5. The process of adaptation to fresh water in gammarid crustaceans is illustrated with reference to a series of species from marine, brackish and freshwater habitats.

Sodium Balance in Eriocheir Sinensis (M. EDW.). The Adaptation of the Crustacea to Fresh Water

1961 ◽  
Vol 38 (1) ◽  
pp. 153-162
Author(s):  
J. SHAW
Keyword(s):  
Fresh Water ◽  
Body Surface ◽  
Eriocheir Sinensis ◽  
Vital Role ◽  
The Body ◽  
Sodium Balance ◽  
Progressive Reduction ◽  
Uptake Mechanism ◽  
Active Uptake ◽  
Main Factors

1. In Eriocheir sinensis active uptake of sodium plays a vital role in the maintenance of sodium balance. At external concentrations down to about 6 mM./l. the active uptake mechanism is fully saturated and the uptake rate just balances the rate of loss, which occurs primarily through the body surface. At lower external concentrations balance may be achieved, at least in part, by the activation of the uptake mechanism. 2. A hypothesis is put forward to account for the mechanism of adaptation of the Crustacea to fresh water. Two main factors are involved: (a) a progressive reduction in the permeability of the body surface to salts and, (b) the acquisition of an active uptake mechanism with a high affinity for the ions which it transports. 3. This hypothesis is discussed in relation to previous theories on the adaptation of the Crustacea to fresh water.

scholarly journals The Effect of External Sodium and Calcium Concentrations on Sodium Fluxes by Salt-Depleted and Non-Depleted Minnows, Phoxinus Phoxinus (L.)

1987 ◽  
Vol 131 (1) ◽  
pp. 417-425
Author(s):  
W. J. FRAIN
Keyword(s):  
Sodium Concentration ◽  
Uptake Mechanism ◽  
Sodium Influx ◽  
Sodium Efflux ◽  
Sodium Uptake ◽  
Km Value ◽  
Concentration Changes ◽  
The Relationship ◽  
Very High ◽  
External Calcium

The relationship between sodium influx and external sodium concentration in Phoxinus is complex and unusual. In non-depleted fish the relationship is approximately that given by the Michaelis-Menten equation of enzyme kinetics. However, the Km value (a measure of the affinity of the sodium uptake mechanism for sodium) is very high (3mmoll−1), indicating a low affinity of the uptake mechanism for sodium. On sodium depletion, the relationship between sodium influx and external sodium concentration changes to produce a curve which has a stepped appearance, and is unusual in that the maximum influx is not increased above that in non-depleted fish. The overall Km alters very little; however, the Km for the lower part of the curve is very low (0.05 mmoll−1). A model is proposed to explain these results in the form of two sodium uptake mechanisms working in parallel across the gill. The second carrier is only active when the fish is sodium-depleted and kept in low external sodium concentrations. Neither the external sodium concentration nor the external calcium concentration has any direct effect on sodium efflux. However, fish depleted in 1 mmoll−1 calcium have a lower sodium efflux than fish depleted in distilled water. Calcium appears to reduce the permeability of the gill to ions such as sodium. Since calcium has no effect on sodium influx, changes in gill permeability do not involve the sodium influxmechanism.

Sodium Regulation and Adaptation to Fresh Water in the Isopod Genus Asellus

1974 ◽  
Vol 61 (3) ◽  
pp. 719-736
Author(s):  
D. W. SUTCLIFFE
Keyword(s):  
Fresh Water ◽  
Loss Rate ◽  
The Body ◽  
Sodium Balance ◽  
Short History ◽  
Sodium Influx ◽  
Km Value ◽  
Sodium Regulation ◽  
Natural Series ◽  
Total Concentrations

1. The principal features of the sodium regulatory mechanism are compared in Asellus communis Say, A. aquaticus (L.) and A. meridianus Rac. 2. Water content and total concentrations of sodium and chloride are similar in the three species, but they differ with respect to values for Kmax, Km, the loss rate, and the minimum sodium balance concentration. 3. It is suggested that A. meridianus, A. aquaticus and A. communis represent a natural series of increasing adaptation to fresh water. A. communis from North America is completely adapted to fresh water. It has the lowest loss rate, the lowest maximum saturation level (Kmax) for sodium influx, and the highest affinity (low Km value) for sodium ions in the transporting system at the body surface. In many respects A. meridianus resembles freshwater populations of Mesidotea entomon and Gammarus duebeni, and may therefore have had a relatively short history in fresh water.

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