Copper uptake across rainbow trout gills
:
mechanisms of apical entry
Martin Grosell* and
Chris M. Wood
McMaster University, Department of Biology, 1280 Main Street West,
Hamilton, Ontario, Canada L8S 4K1
*
Present address: Zoophysiological Laboratory, August Krogh Institute,
University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen Ø,
Denmark
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Fig. 1. Copper (64Cu) uptake (pmol g-1) as a function of
incubation time (h) in juvenile rainbow trout, whole body (including gills)
(pmol g-1) (A) and gills (pmol g-1 gill) (B) assessed at
different copper concentrations. Inset: relative proportion (%) of whole-body
64Cu in the gills as a function of ambient copper concentration
after 2 h of isotope incubation. Values are means ± S.E.M.,
N=8 in all cases.
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Fig. 2. Rates of copper (64Cu) uptake (pmol g-1
h-1) as a function of ambient (A) sodium, (B) potassium and (C)
calcium concentration (nmol l-1) in juvenile rainbow trout assessed
during a 2 h incubation in the presence of 200 nmol l-1 copper.
Values are means + S.E.M., N=8 in all cases. An asterisk indicates a
statistically significant difference from the corresponding control value
(0.05 mmol l-1); two-tailed Student's unpaired t-test with
multisample comparison correction (P<0.05).
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Fig. 3. Rates of sodium (nmol g-1 h-1; left of dotted
vertical line) and copper (pmol g-1 h-1; right of
vertical dotted line) uptake in juvenile rainbow trout (A) during treatment
with 2 µmol l-1 bafilomycin A1 and (B) after treatment with 100
µmol l-1 phenamil assessed during a 2 h incubation in the
presence of 200 nmol l-1 copper. Filled columns indicate results
from pharmacologically treated fish, and open columns indicate results from
corresponding vehicle (DMSO) control fish. Values are means + S.E.M.,
N=8 in all cases. An asterisk indicates a statistically significant
difference from the corresponding control value; two-tailed Student's unpaired
t-test (P<0.05).
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Fig. 4. (A) Overall copper (64Cu) uptake rates (pmol g-1
h-1) in the presence of different ambient sodium concentrations
(indicated by different symbols), (B) calculated `sodium-insensitive' copper
uptake rates (pmol g-1 h-1) and (C) `sodium-sensitive'
copper uptake rates (pmol g-1 h-1) as a function of
ambient copper concentration in juvenile rainbow trout during a 2 h incubation
period. The `sodium-insensitive' copper uptake rates were determined
mathematically as the Jmin (see text) in a hyperbolic
curve fit (SigmaPlot 4.0 for Windows) to copper uptake rates as a function of
ambient sodium concentration. `Sodium-sensitive' copper uptake rates were
determined as the difference between the overall copper uptake and the
`sodium-insensitive' copper uptake. Inset: example of a hyperbolic curve fit:
copper uptake during a 2 h incubation at 145 nmol l-1 copper as a
function of ambient sodium concentration. Values are means ± S.E.M.,
N=8 in all cases.
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Fig. 5. Rates of sodium uptake (nmol g-1 h-1) as a function
of ambient sodium concentration in the presence of different ambient copper
concentrations in juvenile rainbow trout during a 2 h incubation period. The
lines are Michaelis—Menten curves (SigmaPlot 4.0 for Windows), and the
inset summarizes the derived sodium uptake kinetic parameters
Jmax (nmol g-1 h-1) and
Km (µmol l-1). Values are means ±
S.E.M., N=8 in all cases. In the inset, an asterisk indicates a
significant difference from the control condition (18 nmol l-1
copper).
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© The Company of Biologists Ltd 2002
