Open AccessJournal Article
Sodium regulation in the freshwater mollusc Limnaea stagnalis (L.) (Gastropoda: Pulmonata).
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TLDR
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/l, and an experimentally induced reduction of blood volume increases sodium uptake to three times the normal level.Abstract:
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.read more
Citations
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References
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Book
Osmotic Regulation in Aquatic Animals
TL;DR: This book is a systematic presentation of material concerning osmoregulation in each of the major phyla of invertebrates and vertebrates and one chapter is devoted to osmotic problems encountered by eggs and embryos of aquatic animals.
Journal ArticleDOI
Simplified apparatus and procedure for freezing-point determinations upon small volumes of fluid
J A Ramsay,R H J Brown +1 more
TL;DR: In this article, the freezing-point of small volumes of aqueous solutions is determined by first freezing the sample and then determining the thawing point, and the method works best with volumes of the order of 10-3 to 10-4 mm3.
Journal ArticleDOI
Interpretation of the Exchange of Radio-Sodium in Isolated Muscle
TL;DR: Calculated the minimal energy required for extrusion of sodium from the normal frog's sartorius if sodium entered as fast as potassium, and found that more than the energy available from the metabolism of the resting muscle would be needed.
Journal ArticleDOI
The Absorption of Sodium Ions by the Crayfish, Astacus Pallipes Lereboullet : I. The Effect of External and Internal Sodium Concentrations
TL;DR: 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.