The role of environmental calcium in freshwater survival of the marine teleost, Lagodon rhomboides

1976 ◽  
Vol 65 (3) ◽  
pp. 529-538
Author(s):  
J. C. Carrier ◽  
D. H. Evans
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Chelating Agent ◽  
Marine Teleost ◽  
Lagodon Rhomboides ◽  
Na Efflux ◽  
Total Body ◽  
Na Uptake ◽  
Marine Teleost Fish

(1) The marine teleost fish, Lagodon rhomboides, can only tolerate fresh water (5 mM Na) if Ca is also present (10 mM). Transfer to Ca-free fresh water is followed by a substantial increase in radioactive Na efflux with little or no change in the transepithelial potential. Addition of the chelating agent EDTA (2 mM) further increases Na efflux. Fish left in Ca-free fresh water for 2-5 h die with a total body Na less than 50% of that found in animals acclimated to Ca-supplemented fresh water. (2) Rates of Na uptake were measured on either sea-water-acclimated or Ca-supplemented fresh water-acclimated fish transferred to various low Na media. In both cases Na uptake has a high Km, is saturable, inhibited by external NH4, H and amiloride, and is not related to changes in the trans-epithelial potential. (3) It is suggested that L. rhomboides is dependent upon external Ca to decrease diffusional Na loss in low salinities so that a relatively inefficient Na uptake can balance diffusional and urinary Na loss.

ACID-BASE REGULATION, BRANCHIAL TRANSFERS AND RENAL OUTPUT IN A MARINE TELEOST FISH (THE LONG-HORNED SCULPIN MYOXOCEPHALUS OCTODECIMSPINOSUS) DURING EXPOSURE TO LOW SALINITIES

1994 ◽  
Vol 193 (1) ◽  
pp. 79-95 ◽  
Author(s):  
J Claiborne ◽  
J Walton ◽  
D Compton-Mccullough
Keyword(s):  
Teleost Fish ◽  
Sea Water ◽  
Carbon Dioxide Concentration ◽  
Marine Teleost ◽  
Total Acid ◽  
Low Salinity ◽  
External Salinity ◽  
First Time ◽  
Marine Teleost Fish

A number of studies have implied a linkage between acid­base and ion exchanges in both freshwater and seawater fish, although little is known about the branchial and renal acid­base transfers involved as the animals move between different salinities. To investigate the role of these transfers in a marine teleost fish as it is exposed to a dilute environment, we measured plasma acid­base values and net movements from fish to water of NH4+, HCO3- and H+ in long-horned sculpin (Myoxocephalus octodecimspinosus) placed in 100 %, 20 %, 8 % or 4 % sea water for 24­48 h. Renal excretion of H+ was also monitored in fish exposed to 4 % sea water. Sculpin proved to be somewhat euryhaline for they were able to maintain plasma ion and acid­base transfers in hypo-osmotic (20 %) sea water, but could not tolerate greater dilutions for more than several days. Plasma pH and carbon dioxide concentration (CCO2) increased in the 20 % and 8 % dilution groups, with CCO2 nearly doubling (control, 4.56 mmol l-1; 8 % group, 8.56 mmol l-1) as a result of a combined increase in the partial pressure of plasma CO2 (PCO2) and [HCO3-]. During a 44­46 h exposure, HCO3- transfers increased progressively in the most dilute water, with animals in the 8 % and 4 % groups exhibiting a net H+ loss that was smaller than that of seawater fish (control, 5.1 mmol kg-1; 8 %, 0.9 mmol kg-1; 4 %, -2.9 mmol kg-1). Animals exposed to 4 % sea water for 24 h and then returned to normal sea water had a variable plasma pH, an elevated CCO2 and a net efflux of H+ that effectively stopped (control, 0.10 mmol kg-1 h-1; 4 %, 0.02 mmol kg-1 h-1; seawater recovery, 0.20 mmol kg-1 h-1) during the low-salinity period. Renal acid excretion remained relatively constant throughout the experiment but only made up a significant portion (approximately 40 %) of the total acid transfers during the 4 % dilution period (control rate approximately 3 µmol kg-1 h-1: 3 % of branchial rate). We postulate that the increase in plasma CCO2 during exposure to low salinity may be due to mobilization of base from the intracellular bone compartment. The decrease in external salinity could induce base loss by alteration of gill ion exchanges (Na+/H+, Cl-/HCO3-) and/or changes in branchial HCO3- permeability. For the first time, we have shown that the effects of a dilute environment on acid­base transfers may be an important limitation to the survival of a euryhaline species in brackish or fresh water.

Further Evidence for Na/NH, Exchange in Marine Teleost Fish

1977 ◽  
Vol 70 (1) ◽  
pp. 213-220
Author(s):  
DAVID H. EVANS
Keyword(s):  
Teleost Fish ◽  
Sea Water ◽  
External Solution ◽  
Marine Teleost ◽  
Exchange System ◽  
Opsanus Beta ◽  
Transepithelial Potential ◽  
Na Uptake ◽  
Marine Teleost Fish

1. Four species of marine teleosts were shown to possess an external-NH4-inhibited Na uptake from 1 mM-NaCl solutions. The inhibition was not due to changes in the transepithelial potential. 2. Injection of 2 μM-NH4/g fish stimulated Na uptake by Opsanus beta and also stimulated ammonia efflux, 50% of which was dependent upon external Na. 3. The ammonia efflux from three species was partially dependent upon external Na. 4. Na/NH4 exchange in O. beta could be reversed so that 22Na efflux could be stimulated by the addition of 200 mM-NH4 to the external solution. 5. These studies show clearly that marine teleosts possess an Na/NH4 exchange system in sea water which results in a net influx of Na into the fish.

scholarly journals Ca2+-driven intestinal HCO3− secretion and CaCO3 precipitation in the European flounder in vivo: influences on acid-base regulation and blood gas transport

2010 ◽  
Vol 298 (4) ◽  
pp. R870-R876 ◽  
Author(s):  
Christopher A. Cooper ◽  
Jonathan M. Whittamore ◽  
Rod W. Wilson
Keyword(s):  
Teleost Fish ◽  
Gas Transport ◽  
Driving Forces ◽  
Marine Teleost ◽  
Acid Excretion ◽  
Acid Base ◽  
Marine Teleost Fish ◽  
Net Acid Excretion

Marine teleost fish continuously ingest seawater to prevent dehydration and their intestines absorb fluid by mechanisms linked to three separate driving forces: 1) cotransport of NaCl from the gut fluid; 2) bicarbonate (HCO3−) secretion and Cl− absorption via Cl−/HCO3− exchange fueled by metabolic CO2; and 3) alkaline precipitation of Ca2+ as insoluble CaCO3, which aids H2O absorption). The latter two processes involve high rates of epithelial HCO3− secretion stimulated by intestinal Ca2+ and can drive a major portion of water absorption. At higher salinities and ambient Ca2+ concentrations the osmoregulatory role of intestinal HCO3− secretion is amplified, but this has repercussions for other physiological processes, in particular, respiratory gas transport (as it is fueled by metabolic CO2) and acid-base regulation (as intestinal cells must export H+ into the blood to balance apical HCO3− secretion). The flounder intestine was perfused in vivo with salines containing 10, 40, or 90 mM Ca2+. Increasing the luminal Ca2+ concentration caused a large elevation in intestinal HCO3− production and excretion. Additionally, blood pH decreased (−0.13 pH units) and plasma partial pressure of CO2 (Pco2) levels were elevated (+1.16 mmHg) at the highest Ca perfusate level after 3 days of perfusion. Increasing the perfusate [Ca2+] also produced proportional increases in net acid excretion via the gills. When the net intestinal flux of all ions across the intestine was calculated, there was a greater absorption of anions than cations. This missing cation flux was assumed to be protons, which vary with an almost 1:1 relationship with net acid excretion via the gill. This study illustrates the intimate link between intestinal HCO3− production and osmoregulation with acid-base balance and respiratory gas exchange and the specific controlling role of ingested Ca2+ independent of any other ion or overall osmolality in marine teleost fish.

The effects of transecting the IXth and Xth cranial nerves on hydromineral balance in the eel Anguilla anguilla

1976 ◽  
Vol 64 (2) ◽  
pp. 461-475
Author(s):  
N. Mayer-Gostan ◽  
T. Hirano
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Cranial Nerves ◽  
Anguilla Anguilla ◽  
Vagus Nerves ◽  
Rapid Reduction ◽  
Ion Concentrations ◽  
Excess Loss ◽  
Na Efflux ◽  
Hydromineral Balance

The IXth and the Xth cranial nerves in Anguilla anguilla were transected, and the effects upon ion and water balance were studied in fresh water and sea water, and during transfer from fresh water and vice versa. In fresh water there is a slow demineralization due to an excess loss of Na and Cl ions. During freshwater to seawater transfer the eel survives only for 4–5 days. The fish do not drink and Na efflux does not increase enough to extrude excess ions. In sea water the glossopharyngeal and vagus nerves are necessary for the maintenance of the hydromineral balance. Denervation is followed by an increase in plasma ion concentrations. Na fluxes are not modified and increased water loss is not compensated by drinking. The rapid reduction of Na efflux during transfer from sea water to fresh water is not modified by denervation.

THE OSMOREGULATORY ROLE OF THE THYROID GLAND IN THE STARRY FLOUNDER, PLATICHTHYS STELLATUS

1959 ◽  
Vol 37 (6) ◽  
pp. 997-1060 ◽  
Author(s):  
Cleveland P. Hickman Jr.
Keyword(s):  
Thyroid Gland ◽  
Fresh Water ◽  
Body Fluid ◽  
Sea Water ◽  
Salt Water ◽  
Standard Metabolic Rate ◽  
Energy Demands ◽  
Platichthys Stellatus ◽  
Fluid Concentration

Energy demands for osmotic regulation and the possible osmoregulatory role of the thyroid gland were investigated in the euryhaline starry flounder, Platichthys stellatus. Using a melting-point technique, it was established that flounder could regulate body fluid concentration independently of widely divergent environmental salinities. Small flounder experienced more rapid disturbances of body fluid concentration than large flounder after abrupt salinity alterations.The standard metabolic rate of flounder adapted to fresh water was consistently and significantly less than that of marine flounder. In supernormal salinities standard metabolic rate was significantly greater than in normal sea water. These findings agree with the theory that energy demands for active electrolyte transport are greater in sea water than fresh water.Thyroid activity was studied in flounder adapted to fresh water and salt water. Percentage uptake of radioiodine by the thyroid was shown to be an insensitive and inaccurate criterion for evaluating thyroid activity in different salinities because removal rates of radioiodine from the body and blood differed between fresh water and marine flounder. Using thyroid clearance of radioiodine from the blood as a measure of activity, salt-water flounder were shown to have much greater thyroid clearance rates and, hence, more active thyroid glands than flounder adapted to fresh water. The greater activity of the thyroid of marine flounder correlates with greater oxygen demands in sea water and suggests a direct or adjunctive osmoregulatory role of the thyroid gland of fish.

Effect of a chelating agent (EDTA) on zinc uptake and regulation by Palaemon elegans (Crustacea: Decapoda)

1988 ◽  
Vol 68 (1) ◽  
pp. 25-40 ◽  
Author(s):  
D. Nugegoda ◽  
P. S. Rainbow
Keyword(s):  
Sea Water ◽  
Chelating Agent ◽  
The Body ◽  
Zn Uptake ◽  
Zn Concentration ◽  
Zinc Concentrations ◽  
The Mean ◽  
Palaemon Elegans ◽  
Total Body ◽  
Body Concentration

The littoral prawn Palaetnon elegans Rathke regulates the body concentration of zinc at higher external zinc concentrations in the presence of EDTA. The dissolved zinc concentration in artificial sea water corresponding to the threshold of regulation breakdown changed from ca. 100 μg Zn 1-1 (ca. 1.53 μmol Zn 1-1) without EDTA, to ca. 316 μg Zn 1-1 (ca. 4.8 μmo1 Zn 1-1) in the presence of 8.6μmol EDTA 1-1 at 10 °C. The regulated body Zn concentration remained unchanged at 77–79 μg Zn g-1 dry wt with or without EDTA. Increased levels of EDTA in the medium decreased the rate of uptake of labelled zinc by P. elegans. The presence of 3 μmol EDTA 1-1 decreased the mean Zn uptake rate of prawns in 100 fig Zn 1-1 (ca. 1.53 μmol Zn 1-1) from 2.9 to 0.25% of total body Zn g-1 day"1 at 10 °C. The increased ability of P. elegans to regulate zinc in the presence of EDTA may be explained by the reduced bioavailability of the zinc-EDTA complex for uptake. There is marked individual variation in the rate of uptake of labelled zinc in prawns, even in the presence of the same concentration of zinc or zinc-EDTA.

The effect of hypophysectomy and prolactin treatment on the osmotic water influx into the isolated gills of the Japanese eel (Anguilla japonica)

1977 ◽  
Vol 55 (5) ◽  
pp. 872-876 ◽  
Author(s):  
Mizuho Ogawa
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Anguilla Japonica ◽  
Japanese Eel ◽  
Osmotic Permeability ◽  
Water Influx ◽  
In Vitro Technique ◽  
Osmotic Water

An in vitro technique has been used to measure the osmotic water influx into the isolated gills and the osmotic permeability of the gill surface of the Japanese eel, Anguilla japonica. Hypophysectomy increases both of these measurements. Prolactin injections decrease both osmotic water influx and osmotic permeability to water in both the intact and hypophysectomized eels in fresh water but produce no change in either of these parameters when the fish (either intact or hypophysectomized) are in sea water. The possible role of the pituitary (especially prolactin) in osmoregulation of fishes is discussed and considered in relation to the environmental calcium in sea water.

Magnesium transport in freshwater teleosts

1998 ◽  
Vol 201 (13) ◽  
pp. 1981-1990 ◽  
Author(s):  
MJ Bijvelds ◽  
JA Velden ◽  
ZI Kolar ◽  
G Flik
Keyword(s):  
Soft Tissues ◽  
Sea Water ◽  
Molecular Probes ◽  
Magnesium Transport ◽  
Terrestrial Vertebrates ◽  
Magnesium Homeostasis ◽  
Low Magnesium ◽  
Magnesium Uptake ◽  
Total Body

The magnesium handling of freshwater teleost fish is discussed, with an emphasis on the role of branchial, intestinal and renal transport. In response to the eminent threat of constant diffusive losses of minerals such as magnesium, freshwater fish have developed efficient mechanisms for magnesium homeostasis. Magnesium losses are overcome by the uptake of magnesium from the food, making the intestine an important route for magnesium uptake. Some evidence suggests that intestinal magnesium uptake in fish is a regulated, cellular process. The ambient water is an additional magnesium source for fish, implicating the gills as a secondary route for magnesium uptake. Certainly, in some species, direct uptake from the water, probably via branchial routes, ameliorates the effects of a low-magnesium diet. The hard tissues, representing over 50 % of the total body magnesium pool, form a reservoir from which magnesium can be recruited to perform its functions in the cellular metabolism of soft tissues such as muscle. In fish, as in terrestrial vertebrates, the balance of a variety of elements becomes disturbed when the magnesium homeostasis of the soft tissues is disrupted. However, fish appear to be less sensitive than terrestrial vertebrates to these perturbations. Magnesium is reabsorbed in the kidneys to minimise losses. For renal cells, part of a cellular pathway has been elucidated that would allow absorptive magnesium transport (a magnesium conductive pathway in renal brush-border membranes). In some euryhaline teleosts, the kidneys appear to switch instantaneously to rapid magnesium secretion upon magnesium loading, a response common to marine fish that are threatened by diffusive magnesium entry. This enigmatic mechanism underlies the capacity of some euryhaline species to acclimate rapidly to sea water. Despite the progress made over the last decade, much of the cellular and molecular basis of magnesium transport in the gills, intestine and kidneys remains obscure. The application of fluorescent, radioactive and molecular probes, some of which have only recently become available, may yield rapid progress in the field of magnesium research.

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