Blood Composition and Osmoregulation in Ammocoete Larvae

1980 ◽  
Vol 37 (11) ◽  
pp. 1665-1679 ◽  
Author(s):  
Ron Morris
Keyword(s):  
Freshwater Species ◽  
Water Fluxes ◽  
Blood Composition ◽  
Uptake Mechanism ◽  
Water Turnover ◽  
Chloride Uptake ◽  
Osmotic Water ◽  
Lampetra Planeri ◽  
Osmoregulatory Mechanism ◽  
Transport Type

Ammocoetes of all species are typical stenohaline freshwater animals which are able to regulate their blood and tissue ions very efficiently although they live in a very dilute environment. They excrete osmotic water by a well-developed kidney, and water turnover is high. Nephron units are sequentially arranged and have similar differentiated segments to those of other freshwater vertebrates. Total ion loss is low so the kidney must conserve ions efficiently. Ion loss is compensated by an ion-uptake mechanism, probably located in the interplatelet area of the gills. Here, the cells contain a sodium carrier whose transport rate is regulated by internal and external sodium levels; also they have mechanisms for potassium and chloride uptake. Both the gills and kidney have ion transport type cells, but the skin does not. The gills are probably the main access route for water, ions, and lampricides. The freshwater mechanism of osmoregulation persists beyond metamorphosis and thereafter many lampreys become euryhaline, but ammocoetes are unable to osmoregulate in hypertonic solutions and show passive responses. The adults of anadromous species like Lampetra fluviatilis and Petromyzon marinus develop a marine osmoregulatory mechanism which is similar to that of marine teleosts, whilst freshwater species like the landlocked P. marinus of the Great Lakes and the dwarf brook lamprey, Lampetra planeri, show reduced capacities for osmoregulation in seawater.Key words: ammocoetes, lampreys, osmoregulation, blood composition, gills, ion fluxes, kidney, urine, water fluxes, ion compartments

3HOH-osmotic water fluxes and ultrastructure of an epithelial syncytium

1981 ◽  
Vol 61 (2) ◽  
pp. 107-114 ◽  
Author(s):  
D. A. Brodie ◽  
R. B. Podesta
Keyword(s):  
Water Fluxes ◽  
Osmotic Water

scholarly journals Tissue Sources and Blood Flow Limitations of Osmotic Water Transport Across the Peritoneum

1999 ◽  
Vol 10 (2) ◽  
pp. 347-353
Author(s):  
HAILU DEMISSACHEW ◽  
JOANNE LOFTHOUSE ◽  
MICHAEL F. FLESSNER
Keyword(s):  
Blood Flow ◽  
Water Transport ◽  
Water Flow ◽  
Water Flux ◽  
Hypertonic Solution ◽  
Water Fluxes ◽  
Volume Changes ◽  
Doppler Flowmetry ◽  
Chamber Volume ◽  
Osmotic Water

Abstract. Despite the daily use of hypertonic solutions to remove fluid from patients throughout the world who are undergoing peritoneal dialysis, the tissue sources of this water flow are unknown. To study this phenomenon in specific tissues, small plastic chambers were affixed to parietal and visceral surfaces of the peritoneum and were filled with either an isotonic or hypertonic solution. The volume changes over 60 to 90 min were determined and divided by the chamber area to yield the volume flux. The hypertonic solution produced a positive flux into the chamber of 0.6 to 1.1 μl/min per cm2 in all tissues tested. In contrast, the isotonic solution resulted in a net loss or an insignificant change in the chamber volume. Additional experiments tested the influence of blood flow on the hypertonic water flux during periods of control, reduced (50 to 80%), or postmortem (no) blood flow, as determined by laser Doppler flowmetry. With the exception of the liver, small but insignificant changes in the flux into the chamber were observed during the period of reduced flow; all water fluxes were markedly depressed during the postmortem period. It is concluded that both parietal and visceral tissues are sources of osmotically induced water flow into the cavity. Except for the liver, marked blood flow reductions have small but insignificant effects on osmotic water transport.

Asymmetry in osmotic response of frog gastric mucosa

1980 ◽  
Vol 238 (4) ◽  
pp. G298-G302
Author(s):  
L. Villegas
Keyword(s):  
Gastric Mucosa ◽  
Water Flux ◽  
Mucosal Surface ◽  
Ion Fluxes ◽  
Water Fluxes ◽  
Serosal Surface ◽  
Opposite Surface ◽  
Osmotic Water ◽  
Osmotic Response ◽  
Net Water Flux

The effects of hyperosmolality of the serosal and mucosal bathing solutions on the transmucosal net water and ion fluxes were studied in frog gastric mucosa. Addition of 100 mosM glucose to the solution at the serosal surface produces a reversed mucosal-to-serosal net water flux of 7.1 +/- 1.4 microliter . cm-2 . h-1. When added to the abolished spontaneous net water flux, this results in an increment in the net water flux of -17.8 +/- 1.4 microliter . cm-2 . h-1. Addition of the same amount of glucose to the solution at the mucosal surface produces an increment in the serosal-to-mucosal net water flux of 3.7 +/- 1.1 microliter . cm-2 . h-1 when the solution at the opposite surface was kept in 220 mosmol/kg H2O. Simultaneous increments of both solutions of 320 to 420 and 420 to 520 mosM changes the osmotic serosal-to-mucosal induced fluxes to 1.9 +/- 0.9 and 3.4 +/- 1.6 microliter . cm-2 . h-1, respectively. The initial spontaneous net water fluxes measured in 220, 320, and 420 mosM solutions were 11.3 +/- 0.9, 6.9 +/- 1.6, and -1.5 +/- 1.5 microliter . cm-2 . h-1. It is proposed that the osmotic water flux is asymmetric, independent of the solutions tonicities, and not significantly affected by the sweep of solutes at the mucosal surface.

Comparative water flux and daily energy expenditure of lizards of the genus Gallotia (Lacertidae) from the Canary Islands

1995 ◽  
Vol 16 (1) ◽  
pp. 55-66 ◽  
Author(s):  
Marcos Baez ◽  
Roland Vernet ◽  
Jacques Castanet
Keyword(s):  
Energy Expenditure ◽  
Water Flux ◽  
Climatic Conditions ◽  
Daily Energy Expenditure ◽  
Water Fluxes ◽  
Water Turnover ◽  
Doubly Labelled Water ◽  
Water Influx ◽  
Daily Energy ◽  
Average Water

AbstractWater fluxes and daily energy expenditure (DEE) of Gallotia galloti, G. stehlini and G. atlantica, were estimated over a three-year period using the doubly-labelled water (DLW) method. Water influx varied little between seasons and between sexual categories. Juveniles tended to have higher water fluxes in spring in all three species; after a dry period the water turnover tended to decrease for all sexes in G. galloti and G. stehlini, whereas little variation was observed for G. atlantica. The average water influx, combined for all periods, was 46.27, 50.97 and 38.20 ml H2O.kg-1 d-1 for the three species respectively; only the last value differs significantly from the remaining two. The mean DEE, for all periods combined, were 189.7, 179.4 and 146.5 J g-1 d-1 for the three species respectively. As for water turnover, only the value for G. atlantica differed significantly. These data suggest that: G. atlantica may be better adaptated to maintain homeostasis during dry periods and that differences in interspecific DEE can also be explained by others factors than differences in habitat, climatic conditions, daily profiles of activity or body temperatures. We suspect that the incidence of intraspecific competition has more importance in G. atlantica than in the two other species.

Chloride transport through the n onshort-circuited isolated skin of Rana esculenta

1975 ◽  
Vol 228 (3) ◽  
pp. 845-849 ◽  
Author(s):  
F Garcia-Romeu ◽  
J Ehrenfeld
Keyword(s):  
Sodium Transport ◽  
Chloride Transport ◽  
Water Flux ◽  
External Solution ◽  
Rana Esculenta ◽  
Ringer Solution ◽  
Chloride Uptake ◽  
Predominant Component ◽  
Osmotic Water

The effects of acetazolamide (Diamox), ouabain, and amiloride on chloride movements through the isolated, nonshort-circuited Rana esculenta skin were investigated at different external NaCl concentrations. From hyposmotic solutions of low NaCl concentration (2 mM), two principal components of the chloride uptake may be distinguished: one dependent on the osmotic water flux and the other inhibited by Diamox but not by ouabain, amiloride, or removal of sodium from the external solution. Chloride uptake from a Ringer solution is always inhibited when either the sodium transport is blocked with amiloride or ouabain or when sodium is absent from the external solution. It can be concluded that the predominant component of the chloride transport mechanism when the external solution is concentrated (Ringer) is a sodium-dependent one. When chloride is absorbed from a solution of low concentration, however, a component predominated which is independent of sodium transport. It is suggested that the latter mechanism should be capable of exchanging chloride against endogenous base as in the in vivo skin.

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

1960 ◽  
Vol 37 (3) ◽  
pp. 557-572 ◽  
Author(s):  
J. SHAW
Keyword(s):  
Potassium Chloride ◽  
Loss Rate ◽  
Equilibrium Concentration ◽  
Chloride Ions ◽  
Uptake Mechanism ◽  
Chloride Solutions ◽  
Sodium Chloride Solutions ◽  
Chloride Uptake ◽  
Net Uptake ◽  
Chloride Influx

1. The mechanism of chloride uptake in the crayfish, Astacus pallipes, has been investigated. 2. In the absence of chloride uptake, chloride is lost from the animal at a mean rate of 0.8 µM./hr./10 g. body weight. This is about 72% of the sodium loss rate. 3. In salt-depleted animals, chloride balance can be maintained at a minimum external concentration of 0.028 mM./l. This is lower than the corresponding value for sodium. 4. In salt-depleted animals, chloride is taken up from sodium chloride solutions above the equilibrium concentration, but at about one-third of the rate of sodium uptake. From potassium chloride solutions the net uptake of chloride is slight or non-existent. The addition of sodium increases the rate of net chloride uptake from KCl. 5. The chloride influx is always high and is similar from sodium and potassium chloride solutions. The influx is much higher than expected from measurements of loss rate and net uptake. Up to 90% of the influx may be accounted for by exchange diffusion. 6. Activation of the chloride uptake mechanism can be brought about if the animal is made deficient in chloride only. Chloride influx is not increased but the rate of net uptake may now be high and account for 70% of the influx. 7. Net uptake of chloride by chloride-deficient animals takes place against an electrochemical gradient and chloride is exchanged for other anions, probably bicarbonate.

Chloride and osmotic water permeabilities of isolated rabbit renal papillary surface epithelium

1989 ◽  
Vol 257 (2) ◽  
pp. F218-F224 ◽  
Author(s):  
R. K. Packer ◽  
J. M. Sands ◽  
M. A. Knepper
Keyword(s):  
Interstitial Fluid ◽  
Ussing Chamber ◽  
Surface Epithelium ◽  
Fluid Composition ◽  
Water Fluxes ◽  
Chloride Permeability ◽  
Osmotic Water ◽  
Solute Fluxes ◽  
Dilution Potential ◽  
Cl Permeability

The papillary surface epithelium (PSE) covers the mammalian renal papilla. It has been proposed that water or solute fluxes across the PSE might result in changes in urine or medullary interstitial fluid composition. To study osmotic water and chloride permeabilities, the PSE was dissected from underlying medullary tissue and mounted in a small Ussing chamber. Osmotic water permeability was low (14.2 +/- 3.0 microns/s) and was unaffected by 100 nM vasopressin added to the basolateral surface. In contrast, the PSE showed a substantial chloride permeability of 3.1 +/- 0.4 x 10(-5) cm/s that decreased reversibly to 2.2 +/- 0.3 x 10(-5) cm/s (P less than 0.01) with vasopressin. Vasopressin also reversibly increased the transepithelial resistance of the PSE from 87 +/- 9 to 106 +/- 13 omega.cm2 (P less than 0.02). Apical bumetanide (10(-6) M) had no significant effect on PSE chloride permeability. The apparent Na-Cl permeability ratio (0.75 +/- 0.01) calculated from dilution potential measurements was not affected significantly by vasopressin or apical bumetanide. We conclude that it is unlikely that physiologically significant osmotic water fluxes occur across the papillary surface epithelium. However, the NaCl permeability is sufficiently high that physiologically significant transepithelial NaCl fluxes could occur under conditions associated with reflux of urine backward from the papillary tip.

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