First published online June 6, 2005
Journal of Experimental Biology 208, 2421-2431 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01636
Nitric oxide and the control of catecholamine secretion in rainbow trout Oncorhynchus mykiss
B. McNeill and
S. F. Perry*
Department of Biology, University of Ottawa, 10 Marie Curie, Ottawa,
ON, Canada K1N 6N5
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Fig. 1. The effects of the NO donor SNP (5x10–3 mol
l–1; cross-hatched bars; N=6) on (A) noradrenaline
(unfilled component of bars), adrenaline (filled component of bars) and total
catecholamine (sum of noradrenaline + adrenaline) and (B) nitric oxide (NO)
secretion rates over a 10 min period in response to electrical stimulation (60
V,20 Hz) of a perfused posterior cardinal vein preparation of rainbow trout.
Values are means ± 1 S.E.M. A dagger denotes a significant
difference (P<0.5) between pre-stimulated and stimulated samples.
An asterisk denotes a significant difference (P<0.5) between the
control (N=6) and the SNP treated group.
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Fig. 2. The effects of nitric oxide synthase (NOS) inhibitors on (A) noradrenaline
(unfilled bars), adrenaline (filled bars) and total catecholamine (sum of
noradrenaline + adrenaline) and (B) nitric oxide (NO) secretion rates over a
10 min period in response to a bolus injection of 10 mmol l–1
KCl in a perfused posterior cardinal vein preparation of rainbow trout.
Preparations were either pre-treated with saline (N=6) or with saline
containing the combination of the NOS inhibitors 7-NI (10–4
mol l–1) and L-NAME (5x10–3
mol l–1; cross-hatched bars; N=6). Values are means
± 1 S.E.M. A dagger denotes a significant difference
(P<0.5) between pre-KCl and post-KCl samples. An asterisk denotes
a significant difference (P<0.5) between the control and the
inhibitor treated group (cross-hatched).
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Fig. 3. The effects of field stimulation for 2 min at 30 V and either 1 Hz
(N=5), 8 Hz (N=14) or 20 Hz (N=8) on (A)
noradrenaline (unfilled component of bars), adrenaline (filled component of
bars) and total catecholamine (sum of noradrenaline + adrenaline) and (B)
nitric oxide (NO) secretion rates in a perfused posterior cardinal vein
preparation of rainbow rout. Values are means ± 1 S.E.M. A
dagger denotes a significant difference (P<0.5) between
pre-stimulated and stimulated samples (cross-hatched bars).
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Fig. 4. The effects of nitric oxide synthase (NOS) inhibition (using a cocktail of
7-NI and L-NAME; N=9; cross-hatched bars) on (A)
noradrenaline (unfilled component of bars), adrenaline (filled component of
bars) and total catecholamine secretion (sum of noradrenaline + adrenaline)
and (B) nitric oxide (NO) secretion in response to electrical stimulation (30
V, 8 Hz) of a perfused posterior cardinal vein preparation of rainbow trout.
Values are means ± 1 S.E.M. A dagger denotes a significant
difference (P<0.5) between pre-stimulated and stimulated groups.
An asterisk denotes a significant difference (P<0.5) between the
control (N=6) and inhibitor treated group (cross-hatched).
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Fig. 5. The dose-dependent effects of sodium nitroprusside (SNP) on catecholamine
degradation in vitro. (A) The sigmoidal dose–response curve
depicting catecholamine degradation over a 5 min period as a function of SNP
concentration was drawn using iterative curve-fitting software (Sigmaplot).
(B) The data constituting the dose–response curve in A was transformed
to generate the Hill plot. The following linear regression was calculated:
y=0.45x+2.89; r2=0.97. The
EC50 for the Hill plot was calculated to be
2.63x10–7 mol l–1.
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Fig. 6. The effects of the sGC inhibitor ODQ (10–4 mol
l–1; cross-hatched bars; N=6) on (A) noradrenaline
(unfilled component of bars), adrenaline (filled component of bars) and total
catecholamine (sum of noradrenaline + adrenaline) and (B) nitric oxide (NO)
secretion rates in response to field stimulation of 30 V and 8 Hz. Values are
means ± 1 S.E.M. A dagger denotes a significant difference
between pre-stimulation and stimulation. An asterisk denotes a significant
difference between the control (N=6) and ODQ (cross-hatched bars)
treated group.
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Fig. 7. Real-time PCR results showing the expression of rainbow trout iNOS mRNA
relative to anterior kidney. The highest expression of this NOS isoform was
detected in the anterior kidney and the lowest in the anterior posterior
cardinal vein (PCV). Values are means ± 1 S.E.M.;
N=6.
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Fig. 8. The effects of calcium free saline (N=6; cross-hatched bars) on
in situ (A) noradrenaline (filled bar), adrenaline (unfilled bar) and
total catecholamine (sum of noradrenaline + adrenaline) and (B) nitric oxide
(NO) secretion rates in response to electrical stimulation at 30 V and 8 Hz.
Values are means ± 1 S.E.M. A dagger denotes a significant
difference (P<0.5) between pre-stimulated and stimulated groups.
An asterisk denotes a significant difference (P<0.5) between the
control (N=6) and the Ca2+-free treated group
(cross-hatched).
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Fig. 9. The effects of hypoxia followed by electrical stimulation (30 V and 8 Hz)
on (A) noradrenaline (unfilled bars), adrenaline (filled bars) and total
catecholamine (sum of noradrenaline + adrenaline) and (B) nitric oxide (NO)
secretion rates in untreated preparations (N=6; no cross-hatching)
and in preparation treated with saponin (N=6; cross-hatched bars).
Values are means ± 1 S.E.M. A dagger denotes a significant
effect (P<0.5) of hypoxia or electrical stimulation. An asterisk
denotes a significant difference (P<0.5) between the control and
the saponin-treated group.
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© The Company of Biologists Ltd 2005
