Uptake and Loss of Potassium by Rainbow Trout (Salmo Gairdneri) in Fresh Water and Dilute Sea Water

Potassium turnover was studied in rainbow trout, Salmo gairdneri Richardson, adapted to fresh water or 22% sea water using 42K and 86Rb. Potassium space of the whole body increased with time and was about 5 mmol kg−1 after 20h, while Rb+ space under the same conditions was only about 0.5 mmol kg−1, indicating slow penetration of body K+ by Rb+, especially in muscle and red blood cells. Potassium influx, measured by decrease in specific activity of the medium, was 0.07 mmol kg−1 h−1 in fresh water and 0.48 mmol kg−1 h−1 in 22 % sea water; the values for efflux were comparable, indicating that unfed fish are able to maintain K+ balance. In both fresh water and dilute sea water, K+ fluxes are 5% or less of the simultaneous Na+ and Cl− fluxes. The mechanism for K+ fluxes is discussed in terms in K+-ATPases.

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Adaptational Responses of Rainbow Trout to Lowered External Nacl Concentration: Contribution of the Branchial Chloride Cell

Journal of Experimental Biology ◽

10.1242/jeb.147.1.147 ◽

1989 ◽

Vol 147 (1) ◽

pp. 147-168 ◽

Cited By ~ 6

Author(s):

STEVE F. PERRY ◽

PIERRE LAURENT

Keyword(s):

Rainbow Trout ◽

Surface Area ◽

Fresh Water ◽

Primary Response ◽

Chloride Cell ◽

Whole Body ◽

Salmo Gairdneri ◽

Apical Surface ◽

Ionic Fluxes ◽

Area 5

1. Whole-body ionic fluxes and gill chloride cell (CC) morphology were monitored in rainbow trout (Salmo gairdneri) exposed acutely or chronically to natural fresh water (NFW; [Na+]=0.120 mmoll−1; [Cr]=0.164 mmoll−1) or artificially prepared fresh water with reduced [NaCl] (AFW; [Na+]=0.017 mmoll−1; [CT]=0.014 mmoll−1). 2. Net fluxes of Na+ (JnetNa) and Cl− (JnetCl) became extremely negative (indicating net NaCl loss to the environment) upon immediate exposure to AFW exclusively as a result of reduced NaCl influx (JinNa and JinNa). JnetNa and JnetCl were gradually restored to control rates during prolonged (30 days) exposure to AFW. 3. The restoration of JnetCl in AFW was due both to increased JinCl and to reduced Cl− efflux (JoutCl) whereas the primary response contributing to the restoration of JnetNa a t was an increase of JNain. 4. The total apical surface area of branchial CCs exposed to the external environment increased markedly after 24 h in AFW and remained elevated for 1 month as a consequence of enlargement of individual CCs and, to a lesser extent, increased CC density. JinNa and JinNa were correlated significantly with total CC apical surface area. 5. Plasma cortisol levels rose transiently in fish exposed to AFW. Treatment of NFW-adapted fish with cortisol for 10 days (a protocol known to cause CC proliferation) caused pronounced increases in JinCl and JinNa, as measured in both NFW and AFW. 6. These results suggest that an important adaptational response of rainbow trout to low environmental [NaCl] is cortisol-mediated enlargement of branchial epithelial CCs which, in turn, enhances the NaCl-transporting capacity of the gill as a result of the proliferation of Na+ and Cl− transport sites.

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Acclimation to Copper by Rainbow Trout,Salmo gairdneri: Biochemistry

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f87-013 ◽

1987 ◽

Vol 44 (1) ◽

pp. 105-111 ◽

Cited By ~ 152

Author(s):

Darrel Jon Laurén ◽

D. G. McDonald

Keyword(s):

Rainbow Trout ◽

Specific Activity ◽

Gill Tissue ◽

Microsomal Protein ◽

Whole Body ◽

Salmo Gairdneri ◽

Copper Accumulation ◽

Copper Exposure ◽

Copper Uptake ◽

Liver Copper

Whole body, gill, and liver copper uptake, gill Na+-K+-ATPase specific activity, and gill and liver acid-soluble thiols (AST), glutathione, and cysteine of rainbow trout (Salmo gairdneri) were measured during 28 d of exposure to 55 μg copper∙L−1. Na+-K+-ATPase specific activity was inhibited by 33% within 24 h of copper exposure, but this was compensated by a significant increase in microsomal protein so that the total Na+-K+-ATPase activity per milligram of gill tissue returned to normal by day 14. There was no accumulation of copper and no increase in AST, glutathione, or cysteine in the gill. However, after 7 d of exposure, hepatic AST and glutathione had increased by about 2 times, and a sulfhydryl-rich, acid-soluble protein, tentatively identified as metallothionein, increased by 2.8 times. Copper accumulation was highest in the liver, but other tissues also accumulated copper.

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