First published online January 27, 2004
Journal of Experimental Biology 207, 881-890 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.00820
In situ cardiac performance of Pacific bluefin tuna hearts in response to acute temperature change
Jason M. Blank,
Jeffery M. Morrissette,
Ana M. Landeira-Fernandez,
Susanna B. Blackwell,
Thomas D. Williams and
Barbara A. Block*
Tuna Research and Conservation Center, Hopkins Marine Station,
Department of Biological Sciences, Stanford University, Oceanview Boulevard,
Pacific Grove, CA 93950, USA
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Fig. 5. Diving behavior of Atlantic bluefin tunas recorded with electronic tags.
Data on ambient and internal temperature and pressure are recorded at 2 min
intervals for two Atlantic bluefin tuna in the North Atlantic. (A) Fish 521;
219 cm, 179 kg; (B) Fish 485; 208 cm, 154 kg at time of release. Days shown
are representative of behaviors observed daily in the Gulf of Maine (A) and
Flemish Cap (B). Both fish show a pattern of rapid diving into cool water and
regular returns to the surface. Conservation of internal body temperature is
also shown. The lack of any temperature effect (significant cooling) on the
peritoneal cavity suggests that the continuous resurfacing may be associated
with physiological requirements for rewarming of the heart and reoxygenation
of the tissues.
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Fig. 1. Heart rate from a Pacific bluefin tuna heart perfused with Ringer's
solution in situ. Cardiac output pressure data from a single fish at
30°C (top), 15°C (middle) and 2°C (bottom) are shown.
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Fig. 2. Cardiac performance in bluefin tuna in situ. Values of cardiac
parameters were recorded in spontaneously beating bluefin tuna hearts perfused
in situ with oxygenated Ringer's solution at temperatures of
2–25°C. At each test temperature, values were recorded at standard
conditions (open circles) of ambient input pressure and then input pressure
was elevated to maximize stroke volume and cardiac output (A–C, filled
circles). Input and output pressures were then elevated until power output was
maximized (D, filled circles). (A) Heart rate, (B) stroke volume, (C) cardiac
output, (D) power. Values are means ± S.E.M.; N=3
(2°), N=4 (10°, 20°, 25°), N=5 (5°),
N=6 (15°). Significant differences between standard and maximal
conditions (P<0.05) occur in A at 2°C only, in B at all
temperatures, in C at all temperatures  5°C and in D at all
temperatures 10°C. Significant differences between temperatures are
indicated in Table 1. For
details of standard and maximal conditions, see Materials and methods.
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Fig. 3. Comparison of cardiac performance in situ in three tuna species.
Maximal values of cardiac parameters recorded in spontaneously beating hearts
of albacore tuna (red triangles), bluefin tuna (blue squares) and yellowfin
tuna (yellow diamonds) are presented. (A) Heart rate, (B) stroke volume, (C)
cardiac output, (D) power output. Sample sizes for bluefin tuna are as in Fig.
3. Values are means ± S.E.M.; for yellowfin tuna,
N=4 (10°, 25°), N=5 (15°, 20°); for albacore
tuna, N=1.
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Fig. 4. Scope for increase in cardiac output (open symbols) and myocardial power
output (filled symbols) of in situ perfused bluefin tuna hearts at
temperatures of 2–25°C. Scope was calculated from data in
Table 1 as the percentage
difference between mean values of cardiac power output at standard conditions
vs. maximal flow (cardiac output) or maximal power (power output)
conditions.
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© The Company of Biologists Ltd 2004
