In vivo bafilomycin-sensitive Na(+) uptake in young freshwater fish
In vivo treatment with external bafilomycin A(1), a selective inhibitor of V-ATPase H(+) pumps, reduced whole-body Na(+) influx by up to 90 % in young tilapia and 70 % in young carp. The inhibition was rapidly reversible, with whole-body Na(+) influx rebounding to 280 % of pre-treatment values within 20 min of removal from the bafilomycin. This rebound effect is consistent with the prior accumulation of protons during the period when the cells were exposed to bafilomycin. Bafilomycin also inhibited Cl(-) uptake, an effect that was still apparent 30 min after the removal of bafilomycin. These data provide circumstantial evidence for previous suggestions that Na(+) uptake in freshwater fish is associated with a proton-motive force created by a proton pump and indirect evidence for the major significance of this mechanism in the branchial uptake of Na(+) by freshwater fish.
Fenwick
JC
Department of Biology, University of Ottawa, PO Box 450 STN A, Ottawa, Ontario, Canada K1N 6N5 and Department of Animal Physiology, Faculty of Science, University of Nijmegen, Toernooiveld, The Netherlands. james@science.uottawa.ca.
Wendelaar Bonga SE
Flik
G