Studies on the Experimental Alteration of Water and Electrolyte Composition of the Eel (Anguilla Anguilla L.)

Abstract

The distribution of water, electrolyte composition (Na, K, Ca, Mg, PO4, Cl) and extracellular fluid volume of eels (Anguilla anguilla L.) were investigated under different experimental conditions. Adrenalectomy of the freshwater eel was followed by an increase in body weight, a fall in the amount and concentration of sodium in serum and muscle and a shift of water into the cells. The concentration of serum potassium remained within the normal range. Adrenalectomy of the sea-water eel was followed by a decrease in body weight and an increase in the concentration of extra-and intracellular sodium. The concentration of serum calcium also increased, that of potassium remained within the normal range but the actual content diminished.Removal of the corpuscles of Stannius from the freshwater eel gave some effects similar to adrenalectomy. There was, however, no significant increase in body weight but the concentrations of serum potassium and calcium rose. Removal of the corpuscles from the sea-water eel brought about changes similar to, but less pronounced than those after adrenalectomy. The results of the injection of mammalian corticotrophin, cortisol, aldosterone and anti-aldosterone compounds are given. They are discussed in the light of the possible roles of the adrenal cortex and the corpuscles of Stannius in the maintenance of homeostasis of the eel in different environments.

Cortisol treatment improves the development of hypoosmoregulatory mechanisms in the euryhaline rainbow trout, Salmo gairdneri

“…The lowered ion levels in cortisol-treated FW trout indicate increased ion-excretion and/or decreased ion-uptake rates, and is in accordance with observations by Holmes (1959): S. gairdneri, Chan et al (1967) and Henderson and Chester Jones (1967): A. anquilla and by Maetz (1969): Fundulus sp. Since in the present SW transfer experiments both the mortality rates, and changes in ion-osmotic parameters of control fish are well within the ranges normally found in uninjected control fish (Jackson 1981;Leray et al 1981;Alexis et al 1984;Madsen and Naamansen 1989) it is not likely that the handling-injection protocol per se particularly affected SW performance.…”

Effects of ambient ion concentrations on gill ATPases in fresh water eel,Anguilla anguilla

“…Plasma Na + was shown to decrease after acllimation to DW (Chan et al 1967;Masoni et al 1984;. This was confirmed in the present study.…”

Glucocorticoid and mineralocorticoid receptors regulate paracellular permeability in a primary cultured gill epithelium

“…However, deoxycorticosterone is a potent agonist of the MR (Sturm et al, 2005) and is measured at circulating levels of ~0.5-10nmoll -1 in trout (Campbell et al, 1976), leading to the idea that this corticosteroid could contribute to the endocrine control of osmoregulation (see Prunet et al, 2006). Despite these observations, the administration of either aldosterone or deoxycorticosterone in Atlantic salmon parr did not significantly alter the response of fish to a 24h seawater challenge (McCormick et al, 2008), and this lack of response is in agreement with a small number of additional studies that have similarly reported an absence of effect when considering a role for either aldosterone or deoxycorticosterone in salt and water balance in fish (Chan et al, 1967;Takahashi et al, 2006;Umminger and Gist, 1973). Nevertheless, studies have reported that the MR antagonist spironolactone can alter endpoints of osmoregulation in fish and that the effects of spironolactone can differ from the effects of the GR antagonist RU486 (Kiilerich et al, 2007;Scott et al, 2005;Shaw et al, 2007;Sloman et al, 2001).…”