Mechanisms behind Pb-induced disruption of Na+ and Cl - balance in rainbow trout (Oncorhynchus mykiss)

Joseph T. Rogers, Monika Patel, Kathleen M. Gilmour, Chris M. Wood

Research output: Contribution to journalArticle

47 Scopus citations

Abstract

The mechanism of Pb-induced disruption of Na+ and Cl- balance was investigated in the freshwater rainbow trout (Oncorhynchus mykiss). Na+ and Cl- influx rates were reduced immediately in the presence of 2.40 ± 0.24 and 1.25 ± 0.14 μM Pb, with a small increase in efflux rates occurring after 24-h exposure. Waterborne Pb caused a significant decrease in the maximal rate of Na+ influx without a change in transporter affinity, suggesting a noncompetitive disruption of Na+ uptake by Pb. Phenamil and bafilomycin markedly reduced Na + influx rate but did not affect Pb accumulation at the gill. Time-course analysis in rainbow trout exposed to 0, 0.48, 2.4, and 4.8 μM Pb revealed time- and concentration-dependent branchial Pb accumulation. Na +-K+-ATPase activity was significantly reduced, with 4.8 μM exposure resulting in immediate enzyme inhibition and 0.48 and 2.4 μM exposures inhibiting activity by 24 h. Reduced activity was weakly correlated with gill Pb accumulation after 3- and 8-h exposures; this relationship strengthened by 24 h. Reduced Na+ uptake was correlated with gill Pb burden after exposures of 3, 8, and 24 h. Immediate inhibition of branchial carbonic anhydrase activity occurred after 3-h exposure to 0.82 ± 0.05 or 4.30 ± 0.05 μM Pb and continued for up to 24 h. We conclude that Pb-induced disruption of Na+ and Cl- homeostasis is in part a result of rapid inhibition of carbonic anhydrase activity and of binding of Pb with Na+-K+-ATPase, causing noncompetitive inhibition of Na+ and Cl- influx.

Original languageEnglish (US)
Pages (from-to)R463-R472
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume289
Issue number2 58-2
DOIs
StatePublished - Aug 1 2005

    Fingerprint

Keywords

  • Carbonic anhydrase
  • Ionoregulation
  • Na-K-ATPase
  • Waterborne lead

ASJC Scopus subject areas

  • Physiology

Cite this