Ionic Regulation in Rainbow Trout (Salmo Gairdneri) Adapted to Fresh Water and Dilute Sea Water

1979 ◽  
Vol 83 (1) ◽  
pp. 181-192
Author(s):  
F. B. EDDY ◽  
R. N. BATH
Keyword(s):  
Rainbow Trout ◽  
Fresh Water ◽  
Sea Water ◽  
Salmo Gairdneri ◽  
Ionic Regulation ◽  
Tissue Concentrations ◽  
Plasma Ions ◽  
Full Strength ◽  
Water Values ◽  
Eventual Death

Small rainbow trout (5–20 g) adapt to salinities of up to at least 22‰ but not to full strength sea water. In adapted fish plasma ions are regulated nearthe fresh water values, but there is an ionic invasion of the tissues, particularly by Cl− in muscle cells. Analysis of ionic regulation in adapted fish indicates that balance is maintained mainly by expending energy on Cl− regulation. Fish in full strength sea water can no longer regulate Na+ or Cl− in plasma or tissues, which results in high tissue concentrations of these ions and eventual death.

Effects of ergocryptine, prolactin, and growth hormone on survival and ion regulation in rainbow trout, Salmo gairdneri

1978 ◽  
Vol 56 (11) ◽  
pp. 2394-2401 ◽  
Author(s):  
K. J. Brewer ◽  
B. A. McKeown
Keyword(s):  
Growth Hormone ◽  
Rainbow Trout ◽  
Fresh Water ◽  
Sea Water ◽  
Salmo Gairdneri ◽  
Elevated Plasma ◽  
Ion Regulation ◽  
Simultaneous Injection ◽  
Ion Concentrations ◽  
Peripheral Action

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.

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