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

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.

1973 ◽  
Vol 58 (1) ◽  
pp. 105-121
Author(s):  
R. KIRSCH ◽  
N. MAYER-GOSTAN

Using isotopic procedures, the drinking rate and chloride exchanges were studied in the eel Anguilla anguilla during transfer from fresh water to sea water. 1. Following transfer to sea water there is a threefold increase of the drinking rate (lasting about 1 h). Then it falls to a minimum after 12-16 h and rises again to a maximum level about the seventh day after the transfer. Then a gradual reduction leads to a steady value which is not significantly different from the one observed in fresh water. 2. The changes with time of the plasma sodium and chloride concentrations are given. Their kinetics are not completely alike. 3. The chloride outflux increases 40-fold on transfer of the eel to sea water, but even so it is very low. After the sixth hour in sea water there is a progressive increase in the flux, so that on the fourth day it is higher (500 µ-equiv. h-1.100 g-1) than in the seawater-adapted animals (230 µ-equiv.h-1.100 g-1). 4. Drinking rate values in adapted animals are discussed in relation to the external medium. The kinetics of the drinking rate together with variations in body weights after freshwater-seawater transfer are discussed in relation to the possible stimulus of the drinking reflex. 5. Chloride fluxes (outflux, net flux, digestive entry) are compared and lead one to assume that in seawater-adapted fish one-third of the chloride influx enters via the gut and two-thirds via the gills.


1969 ◽  
Vol 43 (1) ◽  
pp. 9-19 ◽  
Author(s):  
I. CHESTER JONES ◽  
D. K. O. CHAN ◽  
J. C. RANKIN

SUMMARY A method for the study of renal function and measurement of mean ventral and dorsal aortic blood pressure for the freshwater and seawater-adapted eel, and during transfer of the animal from fresh water to sea-water, is described. Freshwater eels have higher resting blood pressure, p-aminohippuric acid (PAH) and inulin clearance rates and urine flow than seawater eels. Urine from freshwater animals has low Na, K, Ca, Mg and Cl concentrations, while the clearance rate of inorganic phosphate exceeded that of inulin. Urine from seawater animals has high Na, Ca, Mg and Cl concentrations while that of inorganic phosphate was low. Clearance rates for Ca and Mg greatly exceeded those of inulin. During transfer from fresh water to sea-water there was an initial fluctuation in blood pressure, urine flow and PAH and inulin clearance rates which lasted about 2 hr. Thereafter these gradually declined to values observed for the seawater-adapted animal. The significance of PAH and inulin clearance rates in the study of renal function in the eel and in teleosts in general is discussed.


Author(s):  
K. F. Kelly ◽  
B. J. S. Pirie ◽  
M. V. Bell ◽  
J. R. Sargent

Gills of fresh-water and sea-water eels were perfused at a constant pressure with physiological Ringer containing 10−6 M sodium orthovanadate and examined by light microscopy. The secondary gill filaments were markedly vasoconstricted in both freshwater and sea-water fish although the peripheral blood route around the secondary filaments was unaffected. The central venous space in the primary filament was largely unaffected. Significant constriction of both afferent and efferent arteries on the primary filament occurred. We conclude that orthovanadate vasoconstricts eel gills mainly at the level of the secondary filaments. The study also emphasizes that chloride cells are located on both the primary and secondary filaments of fresh-water gills but solely on the primary filaments of sea-water gills.


1976 ◽  
Vol 65 (3) ◽  
pp. 529-538
Author(s):  
J. C. Carrier ◽  
D. H. Evans

(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.


1993 ◽  
Vol 71 (9) ◽  
pp. 1912-1916 ◽  
Author(s):  
Tim P. Birt ◽  
John M. Green

The ability of nonanadromous Atlantic salmon to regulate hydromineral balance in seawater was assessed by determining plasma Na+ and Cl− concentrations, gill Na+–K+ ATPase activity levels, and gill chloride-cell length in fish exposed to gradually increasing salinity. Plasma ion levels were much higher in nonanadromous salmon exposed to seawater than in anadromous smolts in the same condition, and in both forms held in fresh water. This indicates a lower level of hypoosmoregulatory ability in the nonanadromous form. The activity of gill Na+–K+ ATPase was low in nonanadromous salmon at the beginning of the experiment but increased in response to elevated external salinity. Mortality approached 100% despite increased enzyme activity levels. Salmon retained in fresh water did not exhibit increased enzyme activity. Anadromous smolts exposed to the same conditions exhibited somewhat elevated yet nonlethal plasma ion concentrations. Gill chloride cells increased in size in salmon exposed to seawater and decreased in size in fish held in fresh water. Hypoosmoregulatory inability and a general suppression of the smolting process in some stocks of nonanadromous salmon may be associated with sexual maturation at a young age. However, this is not universal, since nonanadromous salmon in some other stocks mature later yet show clear evidence of reduced smolting.


1978 ◽  
Vol 56 (11) ◽  
pp. 2394-2401 ◽  
Author(s):  
K. J. Brewer ◽  
B. A. McKeown

Ergocryptine, an ergot alkaloid that suppresses prolactin (PRL) secretion and also affects growth hormone (GH) levels in mammals, was injected into juvenile rainbow trout, Salmo gairdneri, averaging 8 to 31 g. In fresh water the drug caused few fatalities but lowered plasma Na+, plasma Ca2+, muscle K+, muscle Mg2+, and haematocrit values. The simultaneous injection of low doses of PRL or GH did not significantly modify the results obtained with the drug alone except for an increase in muscle Mg2+ levels. This suggests a possible peripheral action of the drug.Ergocryptine caused the death of S. gairdneri in dilute sea water, while in certain circumstances PRL and GH prevented mortalities. In this medium the drug caused elevated levels of plasma Ca2+ and muscle K+. The simultaneous injection of ergocryptine plus PRL in hyperosmotic media produced an elevated plasma Na+ concentration but a decrease in intracellular Na+ content and concentration.The results suggest that PRL is not critical for the survival of S. gairdneri in fresh water but may still be necessary to maintain body ion concentrations. In hyperosmotic media, however, PRL and GH may be essential for survival and may act on general metabolic processes rather than specific osmoregulatory organs.


1992 ◽  
Vol 162 (1) ◽  
pp. 197-208 ◽  
Author(s):  
R.G.J. M. HANSSEN ◽  
N. MAYER-GOSTAN ◽  
G. FLIK ◽  
S.E. WENDELAAR BONGA

The cells of the corpuscles of Stannius appeared to be more active in eels acclimated to sea water than in eels acclimated to fresh water. In acclimated eels, however, total and ionic plasma calcium concentrations and stanniocalcin titers did not differ. This suggests that levels of stanniocalcin in freshwater-acclimated eels are sufficient to maintain normocalcemia in sea water. When freshwateracclimated eels were transferred directly to sea water, total and ionic calcium concentrations in the plasma increased significantly within 24 h but there was no apparent effect on the corpuscles of Stannius within the same time. This suggests that changes in secretory activity of the corpuscles of Stannius do not occur rapidly when they are presented with a hypercalcemic challenge. Conversely, when seawater-acclimated eels were transferred to fresh or distilled water there appeared to be a very rapid reduction in secretory activity in the corpuscles of Stannius, as indicated by the rapid accumulation of secretory granules. These data suggest that stanniocalcin turnover is more rapid in seawater-acclimated eels and that the secretory activity of the corpuscles of Stannius is rapidly reduced when a hypercalcic challenge is removed.


1974 ◽  
Vol 144 (1) ◽  
pp. 69-75 ◽  
Author(s):  
John R. Sargent ◽  
Alison J. Thomson

1. Gill tissue from eels adapted to fresh water or to sea water was disrupted in 0.32m-sucrose containing 0.1% (w/v) sodium deoxycholate and the subcellular distribution of (Na++K+)-dependent adenosine triphosphatase was determined. 2. About 70% of the recovered enzyme was in a fraction sedimenting between 225000gav.-min and 6000000gav.-min; the specific activities of enzymes from tissues of freshwater and seawater eels were 16 and 51 μmol of phosphate/h per mg of protein respectively. 3. The enzymes from gills of freshwater and seawater eels were indistinguishable on the basis of a number of parameters. These included phosphorylation by [γ-32P]ATP, the binding of [3H]ouabain, the extent to which bound [3H]ouabain was displaced by increasing concentrations of KCl and pH optima. 4. Electrophoresis on polyacrylamide gels in sodium dodecyl sulphate showed that enzyme preparations from both sources had an identical number of protein components. 5. The higher specific activity of (Na++K+)-dependent adenosine triphosphatase from tissue of seawater eels was accompanied by increased amounts of two protein components. One of these proteins retained 32P after treatment of the enzyme with [γ-32P]ATP and had mol.wt. 97000; the other component was a glycoprotein with mol.wt. approx. 46000. 6. The results are discussed in terms of the nature of the transepithelial NaCl pumps in the gills of freshwater and seawater fish.


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