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.

Sodium, Chloride and Water Balance of the Intertidal Teleost, Pholis Gunnellus

1969 ◽  
Vol 50 (1) ◽  
pp. 179-190
Author(s):  
DAVID H. EVANS
Keyword(s):  
Sea Water ◽  
Electrical Potential ◽  
The Body ◽  
Exchange Diffusion ◽  
Diffusional Permeability ◽  
Diffusion Component ◽  
Na Ions ◽  
Method Of Measurement ◽  
Passive Movements ◽  
Cl Permeability

1. Measurements were made of the regulation of the body ionic content, the fluxes of Na, Cl and water and the electrical potential across the intertidal teleost, Pholis gunnellus in 100% (410 mM-Na/1.) and 20% sea water. 2. The rates of the ion flux depended on the method of measurement. The flux of Cl is much below the flux of Na in 100% sea water. In 20% sea water the fluxes of Na and Cl are the same. 3. In 100% sea water only the Na flux has an exchange-diffusion component. There is no exchange-diffusion component of the flux of either ion in 20% sea water. 4. The electrical potential across Pholis changes from 18 mV. (inside positive) in 100% sea water to 6 mV (inside negative) in 100% sea water. Comparison with the Nernst potentials indicate that Cl is actively transported in both salinities while Na may possibly be actively transported in 100% sea water. 5. In 20% sea water the permeability to Na decreases to 51% of the permeability in 100% sea water, while the Cl permeability decreases to 82% and the water permeability remains at the sea-water level. 6. In both salinities the rate of diffusion of Na ions is greater than the rate of diffusion of Cl ions. 7. The osmotic permeability to water is approximately equal to the diffusional permeability to water in both salinities. 8. It is concluded that the passive movements of Na, Cl and water must be independent of each other and not via uncharged, water-filled pores.

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.

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.

The Effect of External Potassium Ions on the Electrical Potential Measured Across the Gills of the Teleost, Dormitator Maculatus

1974 ◽  
Vol 61 (2) ◽  
pp. 277-283
Author(s):  
DAVID H. EVANS ◽  
JEFFREY C. CARRIER ◽  
MARGARET B. BOGAN
Keyword(s):  
Sea Water ◽  
Electrical Potential ◽  
Potassium Ions ◽  
Sodium Efflux ◽  
Electrical Potentials ◽  
External Potassium ◽  
Potassium Influx ◽  
Sodium Extrusion ◽  
Sufficient Magnitude ◽  
Stimulation Of

1. A technique has been developed for the measurement of electrical potentials (TGP's) across the gills of free-swimming, Dormitator maculatus. 2. Transfer of fish to various KCl solutions is correlated with changes in the TGP, which are not of sufficient magnitude to account for the known potassium stimulation of sodium efflux from this species. 3. Transfer to potassium-free sea water results in little or no change in TGP while previous results have shown that such a transfer is correlated with a 22% reduction of sodium efflux. 4. Transfer to fresh water results in a reduction of TGP from +17 mV (inside positive) to -36 mV which is sufficient to account for the instantaneous reduction in sodium efflux previously shown for this species. 5. It is concluded that while changes in TGP can account for the ‘Na-free effect’ in D. maculatus they cannot account for the potassium effects on sodium extrusion. This supports the previous conclusion that sodium efflux and potassium influx are chemically linked in this species.

scholarly journals On the Mechanism of Sodium Extrusion across the Irrigated Gill of Sea Water-Adapted Rainbow Trout (Salmo gairdneri)

1974 ◽  
Vol 64 (2) ◽  
pp. 148-165 ◽  
Author(s):  
Leonard B. Kirschner ◽  
Lewis Greenwald ◽  
Martin Sanders
Keyword(s):  
Rainbow Trout ◽  
Active Component ◽  
Sea Water ◽  
Salmo Gairdneri ◽  
Sodium Efflux ◽  
Exchange Diffusion ◽  
The Difference ◽  
Sodium Extrusion ◽  
Trout Gill ◽  
Electrical Data

Sodium efflux (JoutNa) across the irrigated trout gill was rapid in sea water (SW), but only about 25 % as large in fresh water (FW). The difference correlated with a change in the potential difference across the gill (TEP). The latter was about +10 mV (blood positive) in SW, but –40 mV in FW. Both flux and electrical data indicated that gills in this fish are permeable to a variety of cations including Na+, K+, Mg2+, choline, and Tris. They are less permeable to anions; PNa:PK:PCl was estimated to be 1:10:0.3, and PCl > Pgluconate. The TEP was shown to be a diffusion potential determined by these permeabilities and the extant ionic gradients in SW, FW as well as in other media. JoutNa appeared to be diffusive in all of the experiments undertaken. Exchange diffusion need not be posited, and the question of whether there is an active component remains open.

Potassium transport by flounder intestinal mucosa

1984 ◽  
Vol 246 (6) ◽  
pp. F946-F951 ◽  
Author(s):  
R. A. Frizzell ◽  
D. R. Halm ◽  
M. W. Musch ◽  
C. P. Stewart ◽  
M. Field
Keyword(s):  
Apical Membrane ◽  
Basolateral Membrane ◽  
Electrical Potential ◽  
Electrical Potential Difference ◽  
Cell Type ◽  
K Secretion ◽  
Single Cell Type ◽  
Free Media ◽  
Membrane Electrical Potential ◽  
K Transport

We studied the mechanisms of K transport across an epithelium in which NaCl absorption is mediated primarily by Na/K/Cl cotransport at the apical membrane. Rubidium served as a reliable K substitute; under control conditions, both K and Rb were actively secreted. During secretion, K (Rb) enters across the basolateral membrane via the Na/K pump and exits across the apical membrane through K conductance pathways, since serosal ouabain or mucosal barium abolished K secretion, mucosal furosemide or Cl-free media blocked K secretion by interfering with access of Na to the pump, and elevated mucosal solution [K] or [Rb] depolarized the apical membrane electrical potential difference. Mucosal Ba unmasked active Rb absorption that could be blocked by mucosal furosemide. These findings illustrate active K absorption and secretion across an epithelium that comprises a single cell type in which opposing K fluxes across the apical membrane are mediated by Na/K/Cl cotransport entry and conductive K exit. The direction of transepithelial K transport is determined by the relative activities of these pathways.

scholarly journals Direct Conversion of Standard Sea Water Electrolyte to Electrical Energy

KnE Energy ◽  
2015 ◽  
Vol 1 (1) ◽  
pp. 135
Author(s):  
Sugandar Sumawiganda
Keyword(s):  
Fuel Cell ◽  
Energy Conversion ◽  
Sea Water ◽  
Strong Electric Field ◽  
Electrical Potential ◽  
Electrical Energy ◽  
Hydrogen Gas ◽  
Electrical Potential Difference ◽  
Free Gibbs Energy ◽  
Free Ions

<p>This paper explains the techno-economical feasibility of very efficient direct energy conversion of standard seawater electrolytes to electrical energy based on solid state power electronics. It can be shown by applying free Gibbs energy concept and chemical REDOX reaction that the ions are in higher entropy than their associated solid crystal’s form, and therefore they have higher potential energy. The key problem is obviously to separate these free ions in separate subspaces according to its charge, since this separation will create electrical potential difference between them. The ions are essentially  electrons carrier and therefore despites they are moving with random velocity magnitude and direction, the external observer will observe an increasing electric charge due to free ions influx. This separation and migration can be performed by a rather strong electric field created by a special varnish insulated wire grid, VIWG. It will be shown that the energy expenditure for the liberation of ions from hydrates structure containment and migrate them to separate subspaces is  similar to energy activation for the oxidation exothermal process, which requires only marginal external energy. Thus the energy gain is 250 kJoule/kg standard seawater, which is only 0.55% of the fuel value of 1kg Texas’ crude oil, U.S.A. Unlike thermal energy conversion, this system may has 95% efficiency, since all rotating machines are eliminated. With this efficency, the “priceless” seawater feedstock leads to the electric energy tariff which can be as low as 30% of the current one. In addition, this system  provides with a number of significant comparative and competitive advantages compare to any known energy generation technology today, a.o.: zero pollution process, significant by products (fresh water, hydrogen gas, pure solid crystal atoms precipates) renewable since the availabilty of seawater feedstock is unlimited, scalable, modular, small foot-print, co-generation of Sodium/Chlorine fuel cell, and table salt (NaCl), and conventioanl hydrogen/oxygen fuel cell. It can be modified as power house for any kind of ship, as small as traditional fishing vessel to ocean liner. </p><p><strong>Keywords</strong>: Gibbs free energy, REDOX, hydrates, zero polution, fuel cell, scalable, modular </p><p> </p>

OSMOTIC INHIBITION OF THE NATRIFERIC RESPONSE OF THE TOAD URINARY BLADDER TO VASOPRESSIN

1975 ◽  
Vol 67 (1) ◽  
pp. 119-125
Author(s):  
P. J. BENTLEY
Keyword(s):  
Urinary Bladder ◽  
Water Movement ◽  
Short Circuit ◽  
Electrical Potential ◽  
Short Circuit Current ◽  
Toad Bladder ◽  
Toad Urinary Bladder ◽  
Electrical Potential Difference ◽  
Osmotic Gradient

SUMMARY The electrical potential difference and short-circuit current (scc, reflecting active transmural sodium transport) across the toad urinary bladder in vitro was unaffected by the presence of hypo-osmotic solutions bathing the mucosal (urinary) surface, providing that the transmural flow of water was small. Vasopressin increased the scc across the toad bladder (the natriferic response), but this stimulation was considerably reduced in the presence of a hypo-osmotic solution on the mucosal side, conditions under which water transfer across the membrane was also increased. This inhibition of the natriferic response did not depend on the direction of the water movement, for if the osmotic gradient was the opposite way to that which normally occurs, the response to vasopressin was still reduced. The natriferic response to cyclic AMP was also inhibited in the presence of an osmotic gradient. Aldosterone increased the scc and Na+ transport across the toad bladder but this response was not changed when an osmotic gradient was present. The physiological implications of these observations and the possible mechanisms involved are discussed.

Reversal of glibenclamide and voltage block of an epithelial KATP channel

1996 ◽  
Vol 271 (4) ◽  
pp. C1122-C1130 ◽  
Author(s):  
O. Mayorga-Wark ◽  
W. P. Dubinsky ◽  
S. G. Schultz
Keyword(s):  
Hydrophobic Interactions ◽  
Basolateral Membrane ◽  
Electrical Potential ◽  
Membrane Vesicles ◽  
Voltage Gating ◽  
Electrical Potential Difference ◽  
Outer Solution ◽  
Channel Inhibition ◽  
K Concentration ◽  
Voltage Gate

K+ channels present in basolateral membrane vesicles isolated from Necturus maculosa small intestinal cells and reconstituted into planar phospholipid bilayers are inhibited by MgATP and sulfonylurea derivatives, such as tolbutamide and glibenclamide, when these agents are added to the solution bathing the inner mouth of the channel. In addition, these channels possess an intrinsic "voltage gate" and are blocked when the electrical potential difference across the channel is oriented so that the inner solution is electrically positive with respect to the outer solution. We now show that increasing the concentration of permeant ions such as K+ or Rb+ in the outer solution reverses channel inhibition resulting from the addition of 50 microM glibenclamide to the inner solution and also inhibits intrinsic voltage gating; these effects are not elicited by increasing the concentrations of the relatively impermeant ions, Na+ or choline, in the outer solution. Furthermore, increasing the K+ concentration in the outer solution in the absence of glibenclamide inhibits voltage gating, and, under these conditions, the subsequent addition of glibenclamide to the inner solution is ineffective. These results are consistent with a model in which the voltage gate is an open-channel blocker whose action is directly reversed by elevating the external concentration of relatively permeant cations and where the action of glibenclamide is to stabilize the inactivated state of the channel, possibly through hydrophobic interactions.

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