Covariation in regulation of affinity for branchial zinc and calcium uptake in freshwater rainbow trout

Christer Hogstrand, Nathan Webb, Chris M. Wood

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53 Scopus citations

Abstract

The possible coupling between regulation of the affinities for branchial Zn and Ca influx was investigated in juvenile rainbow trout Oncorhynchus mykiss acclimated to relatively hard fresh water ([Ca]=l.0 mmoll-1). The K(m) for branchiai Ca influx was manipulated experimentally by exposing the fish to 2.3 μmoll-1 waterborne Zn for a total of 28 days. This procedure resulted in rapidly increased K(m) values for both Ca and Zn influx, an effect that remained through the experimental period. There was a significant linear correlation (r=0.88, P<0.02) between K(m) values for Ca and Zn measured at the same time points. Zn exposure caused progressively increasing maximum rate of transport, J(max), values for Zn relative to the control value, but there was little, if any, effect on J(max) for Ca. These results support the idea of a shared transport site for Zn and Ca at the apical membrane of the gill epithelium and suggest that there is a certain degree of coregulation of branchial Zn and Ca uptake in rainbow trout. Removal of Ca from the water resulted in a large (six- to 24-fold) increase in affinity (decreased K(m)) for Zn influx and a modest (1.1- to 1.8-fold) increase in J(max) for Zn. Thus, Ca is a competitive inhibitor of Zn influx. In water lacking Ca, the K(m) for Zn in Zn-acclimated fish was no different from that of the control fish, suggesting that the Ca2+/Zn2+ transporter was regulated to improve Ca uptake.

Original languageEnglish (US)
Pages (from-to)1809-1815
Number of pages7
JournalJournal of Experimental Biology
Volume201
Issue number11
StatePublished - Jun 1 1998

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Keywords

  • Acclimation
  • Branchial
  • Calcium
  • Fish
  • Gill
  • Influx
  • Oncorhynchus mykiss
  • Rainbow trout
  • Regulation
  • Uptake
  • Zinc

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Agricultural and Biological Sciences (miscellaneous)

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