First published online March 12, 2009
Journal of Experimental Biology 212, 934-944 (2009)
Published by The Company of Biologists 2009
doi: 10.1242/jeb.027680
Nervous and humoral control of cardiac performance in the winter flounder (Pleuronectes americanus)
Paula C. Mendonça and
A. Kurt Gamperl*
Ocean Sciences Centre, Memorial University, St John's, Canada, NL A1C
5S7
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Fig. 1. Cardiac output (ml min–1 kg–1) and dorsal
aortic pressure (kPa) traces for one winter flounder. These traces are
approximately 30 s in duration and were obtained 1 h after each drug
injection. The drugs were sequentially injected every 1 h 30 min in the
following order: atropine (1.2 mg kg–1), bretylium (10 mg
kg–1), atenolol (213 µgkg–1) and ICI 118
551 (250 µgkg–1).
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Fig. 2. Cardiovascular responses to sequential drug (solid circles) and saline
(open squares) administration in the winter flounder. Saline and drug
injections were made every 1 h 30 min. Drugs were administrated in the
following order: atropine (1.2 mg kg–1), bretylium (10 mg
kg–1), atenolol (213 µgkg–1) and ICI
118551 (250 µgkg–1); measurements were taken 1 h after
each injection. Values are means ± s.e.m. Saline group, N=7
for all parameters; experimental group, N=8, except dorsal aortic
pressure and total vascular resistance (N=6). *Values
significantly different (P<0.05) from pre-injection values.
aDifferent from previous treatment. bDifference between
saline and corresponding drug injections.
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Fig. 3. Maximum cardiovascular responses of winter flounder to saline
administration (open squares) and increasing doses of catecholamines (solid
circles). Saline and catecholamines were injected every 1 h. Catecholamines
were administrated in the following order: 0.1 and 0.05 (dose 1), 0.15 and
0.075 (dose 2), 0.2 and 0.1 (dose 3), 0.3 and 0.15 (dose 4) and 0.4 and 0.2
µgkg–1 (dose 5) of adrenaline and noradrenaline,
respectively. Values are means ± s.e.m., N=7.
*Values significantly different (P<0.05) from
pre-injection values. aDifferent from the previous dosage.
bDifference between saline-injected fishes and the corresponding
catecholamine dosage.
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Fig. 4. Percentage change in winter flounder cardiovascular parameters due to
catecholamine administration. Catecholamines were injected every 1 h.
Catecholamines were administrated in the following order: 0.1 and 0.05 (dose
1), 0.15 and 0.075 (dose 2), 0.2 and 0.1 (dose 3), 0.3 and 0.15 (dose 4) and
0.4 and 0.2 µgkg–1 (dose 5) of adrenaline and
noradrenaline, respectively. *Values significantly different
(P<0.05) from pre-injection values. Values are means ±
s.e.m., N=7.
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Fig. 5. (A) Total, non-specific and specific binding of [3H]CGP-12177 to
ventricular β-adrenoreceptors in the winter flounder; timolol
(10–5 nmol l–1) was used as the competitor
(N=8). (B) Specific binding of [3H]CGP-12177 to
ventricular β-adrenoreceptors in winter flounder (y=36.2 Ln(x)+103.8;
r2=0.963; N=8). (C) Comparison of the ability of
atenolol (β1-antagonist; solid circles) and ICI
118551(β2-antagonist, open squares) to displace
[3H]CGP-12177 from ventricular β-adrenoreceptors in the winter
flounder (N=6). ICI 118551
IC50=1.91x10–6 mol l–1.
Values represent means ± s.e.m.
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© The Company of Biologists Ltd 2009
