The Ionic Relations of Artemia Salina (L.)

1969 ◽  
Vol 51 (3) ◽  
pp. 727-738
Author(s):  
P. G. SMITH
Keyword(s):  
Sea Water ◽  
Electrical Potential ◽  
Artemia Salina ◽  
Potential Difference ◽  
Electrical Potential Difference ◽  
Gill Epithelium ◽  
Electrical Measurements ◽  
Lithium Ions ◽  
Cation Permeability ◽  
Made In

1. Measurements of ion concentrations and of electrical potential difference and resistance have been made in Artemia salina, the brine shrimp, using animals acclimatized to sea water. It is believed that the results of the electrical measurements are largely determined by the characteristics of the gill epithelium. 2. The potential difference between the blood and external medium in sea water is +23 mV. (blood positive). Considered in relation to the ionic concentrations, this indicates that chloride is subject to active transport out of the animal, potassium is pumped in, and sodium is approximately in equilibrium. 3. Measurements of potential difference in other solutions give the permeability ratios Na:K:Li:Cl as 1.00:0.6:1.0:0.11. 4. The resistance of the gill epithelium in sea water is 40 Ωcm.2. 5. Measurements of resistance in other solutions suggest that lithium ions induce a decrease in cation permeability.

The Ionic Relations of Artemia Salina (L.)

1969 ◽  
Vol 51 (3) ◽  
pp. 739-757
Author(s):  
P. G. SMITH
Keyword(s):  
Sea Water ◽  
Electrical Potential ◽  
Artemia Salina ◽  
Electrical Potential Difference ◽  
External Concentration ◽  
Sodium Efflux ◽  
Exchange Diffusion ◽  
Similar Shape ◽  
Diffusional Permeability ◽  
Free Media

I. The effects of different external media on the sodium and chloride efflux in Artemia salina, the brine shrimp, have been observed, using animals acclimatized to sea water. In sea water, both sodium and chloride fluxes across the epithelium are approximately 7,000 pmole cm.-2 sec.-1. 2. Sodium efflux drops markedly in sodium-free media, and chloride efflux falls in chloride-free media; the two effects are independent, and are not due to changes in external osmolarity. 3. The decreases in sodium efflux can be explained by changes in electrical potential difference and diffusional permeability; exchange diffusion of sodium does not occur. 4. Approximately 70% of the chloride efflux is due to exchange diffusion, and most of the remainder is due to active transport. 5. It is shown that graphs of ion efflux against external concentration which can be fitted by a Michaelis-Menten equation do not constitute evidence for the presence of exchange diffusion; graphs of similar shape can be obtained if the flux is simply diffusional. 6. The drinking rate, determined from the rate of uptake of 131I-polyvinylpyr-rolidone, is 36 pl. sec.-1, or 2.0% body weight hr.-1. 7. The diffusional influx of water is 240 pl. sec.-1.

scholarly journals Electrical-Potential Difference and Sodium Ion Fluxes across the Integument of Corophium Volutator (Crustacea; Amphipoda), a Euryhaline Hyperosmotic Regulator

1985 ◽  
Vol 114 (1) ◽  
pp. 477-491
Author(s):  
Peter M. Taylor
Keyword(s):  
Electrical Potential ◽  
Potential Difference ◽  
Electrical Potential Difference ◽  
Transport Mechanisms ◽  
Gill Epithelium ◽  
High Permeability ◽  
Corophium Volutator ◽  
Efflux Rate ◽  
Na Efflux ◽  
Efflux Rate Constant

1. Measurements of electrical-potential difference (TEP) and Na+ efflux, across the integument have been made for Corophium volutator acclimated to 85 or 15%SW. 2. The TEP of acclimated animals in 85 or 15%SW is l.4mV or 11.1 mV respectively (haemolymph negative). For acclimated animals, unidirectional Na+ efflux is 154.3 nmol mg−1 body weight h−1 in 85%SW [efflux rate constant (k) = 0.70 h-1] and approximately 35.5 nmol mg−1 h−1 in 15%SW (k = 0.50h−1 in 10%SW). 3. The results indicate that Na+ and Cl−are passively distributed across the ion-permeable (gill) integument of acclimated animals in 85%SW, but that active uptake of Cl−, and possibly Na+ also, occurs across the gills of acclimated animals in 15%SW. The ion transport mechanisms appear to effect electroneutral transfers across the gill integumental epithelium. 4. Corophium volutator gill integument has a high permeability to ions; permeability to Na+(PNa) is 7.5×10−8ms−1, and the ratio PCl/PNa is 0.45, for animals acclimated to either salinity. The resistance of the gill epithelium of acclimated animals has been calculated to be 5.3×10−3Ωm2 and 2.0×10−2Ωm2 in 85 and 15%SW respectively.

Osmoregulation in the Larva of the Marine Caddis Fly, Philanisus Plebeius (Walk.) (Trichoptera)

1972 ◽  
Vol 57 (3) ◽  
pp. 821-838
Author(s):  
JOHN P. LEADER
Keyword(s):  
Sodium Chloride ◽  
Osmotic Pressure ◽  
Body Surface ◽  
Sea Water ◽  
Electrical Potential ◽  
Chloride Ion ◽  
Chloride Ions ◽  
The Body ◽  
Electrical Potential Difference ◽  
Caddis Fly

1. The larva of Philanisus plebeius is capable of surviving for at least 10 days in external salt concentrations from 90 mM/l sodium chloride (about 15 % sea water) to 900 mM/l sodium chloride (about 150 % sea water). 2. Over this range the osmotic pressure and the sodium and chloride ion concentrations of the haemolymph are strongly regulated. The osmotic pressure of the midgut fluid and rectal fluid is also strongly regulated. 3. The body surface of the larva is highly permeable to water and sodium ions. 4. In sea water the larva is exposed to a large osmotic flow of water outwards across the body surface. This loss is replaced by drinking the medium. 5. The rectal fluid of larvae in sea water, although hyperosmotic to the haemolymph, is hypo-osmotic to the medium, making it necessary to postulate an extra-renal site of salt excretion. 6. Measurements of electrical potential difference across the body wall of the larva suggest that in sea water this tissue actively transports sodium and chloride ions out of the body.

scholarly journals Transmural electrical potential difference in the mammalian esophagus in vivo

1978 ◽  
Vol 75 (2) ◽  
pp. 286-291 ◽  
Author(s):  
Keith S. Turner ◽  
Don W. Powell ◽  
Charles N. Carney ◽  
Roy C. Orlando ◽  
Eugene M. Bozymski
Keyword(s):  
Electrical Potential ◽  
Potential Difference ◽  
Electrical Potential Difference
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