Cortisol stimulates whole body calcium uptake and the branchial calcium pump in freshwater rainbow trout.
Exposure of rainbow trout to a reduced ambient calcium level (from 490 to 25 mumol Ca2+/l) caused hypocalcaemia and induced a rapid increase (within 1 h) in systemic cortisol levels. Under conditions of low environmental calcium concentrations, cortisol levels remained increased for at least 8 days. After this time the in-vitro Ca2+-transport capacity of branchial basolateral membrane vesicles was increased due to stimulation of Ca2+-ATPase activity, presumably as a result of chloride cell proliferation. Pituitary prolactin cells were unaffected by low ambient calcium levels. Fish kept in water containing 490 mumol Ca2+/l and treated with cortisol for 7 days displayed an increase in whole body calcium uptake and an enhancement of the branchial calcium transport capacity; concomitantly, hypercalcaemia was observed. We conclude that, in the rainbow trout, cortisol exerts hypercalcaemic effects by stimulating Ca2+ uptake from the water and that this effect forms an intrinsic part of the established mineralocorticoid action of cortisol in fish.
Flik
G
G
Department of Animal Physiology, Faculty of Science, University of Nijmegen, The Netherlands.
Perry
S F
SF
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000097:blood / Q000493:pharmacokinetics*; D005260:Female; D005880:Gills / Q000378:metabolism*; D006854:Hydrocortisone / Q000031:analogs & derivatives* / Q000097:blood / Q000494:pharmacology; D008274:Magnesium / Q000097:blood; D008297:Male; D012487:Salmonidae / Q000502:physiology*; D012964:Sodium / Q000097:blood; D013997:Time Factors; D014337:Trout / Q000502:physiology*
D012964:Sodium; D000251:Adenosine Triphosphatases; D008274:Magnesium; C007133:hydrocortisone hemisuccinate; D002118:Calcium; D006854:Hydrocortisone