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First published online September 16, 2005
Journal of Experimental Biology 208, 3665-3674 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01815

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Perfusion of the isolated trout heart coronary circulation with red blood cells: effects of oxygen supply and nitrite on coronary flow and myocardial oxygen consumption

F. B. Jensen^1,* and C. Agnisola²

¹ Institute of Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
² Department of Biological Sciences, University of Naples Federico II, Napoli, Italy

View larger version (27K): [in a new window]   Fig. 1. Scheme of the perfusion set-up. The isolated heart was mounted into a saline-filled, temperature-controlled chamber. The coronary cannula was connected to two input reservoirs, one filled with saline (maintained at constant level by a re-circulating pump; not shown) and the other filled with the red blood cell (RBC) suspension. Perfusion could be shifted between the two reservoirs via a three-way tap. Each reservoir was associated with a coronary flow measurement device similar to that described by Agnisola et al. (1994), but computer controlled. The aortic cannula was occluded so the output from the preparation was into the chamber via the atrial cannula. An ISO-NOP electrode was inserted into the atrial cannula to measure relative changes in NO level in the effluent from the preparation. The saline level in the chamber was kept constant by an overflow. Samples could be taken from both input and atrium.

View larger version (12K): [in a new window]   Fig. 2. Relationship between myocardial O2 consumption (O2) and (A) input O2 concentration, (B) coronary flow or (C) the O2 extraction coefficient during perfusion of the isolated trout heart coronary circulation with saline (open circles) and red blood cell (RBC) suspensions (filled circles). The solid line in A is the linear regression between O2 and input CO2, using all saline and RBC perfusion points (y=0.432x; R=0.85, N=40, P<0.0001), and the broken line in B shows the linear relationship between O2 and coronary flow during RBC perfusion (y=6.6x+0.6; R=0.81, N=17, P=0.00013).

View larger version (13K): [in a new window]   Fig. 3. Relationship between Hb O2 saturation (SO2) and oxygen tension (PO2) in samples taken from the input and the atrium. The broken curve shows the overall in situ O2 equilibrium curve. See text for details. (1 mmHg=133.3 Pa.)

View larger version (24K): [in a new window]   Fig. 4. Representative NO trace showing the NO signal as a function of time during saline perfusion, after switching to red blood cell (RBC) perfusion and after nitrite addition. The grey curve is the raw signal (3 measurements s-1), and the black curve is the isolated NO signal, resulting from a 400-point adjacent averaging smoothing of the raw data.

View larger version (9K): [in a new window]   Fig. 5. NO production in the isolated, non-working trout heart preparation. Open bars: perfusion in absence of L-NA; filled bars: perfusion in presence of L-NA. (A) NO production rate during saline perfusion; (B) change in the NO production rate during RBC perfusion; (C) change in the NO production rate after addition of nitrite to RBC perfusate. # signifies that NO production or NO production is significantly different from zero. * signifies a significant effect of L-NA.

View larger version (12K): [in a new window]   Fig. 6. Relationship between NO production rate and ventricle mass following the switch from saline perfusion to RBC perfusion in the absence of L-NA (y=–90x+32.4; R=–0.95, P=0.015).

View larger version (13K): [in a new window]   Fig. 7. Methaemoglobin (metHb) content and extracellular [NO2-] in input and atrium samples during RBC + nitrite perfusion of the coronary circulation. * signifies a significant difference in metHb.

View larger version (15K): [in a new window]   Fig. 8. Comparison of mean values for (A,D) input oxygen concentration (CO2), (B,E) myocardial oxygen consumption (O2) and (C,F) coronary flow () during saline perfusion, red blood cell (RBC) perfusion and RBC + nitrite perfusion in the absence (A–C) and presence (panels D–F) of L-NA. # signifies significant effects of L-NA; * signifies significant effects of RBC perfusion or RBC + nitrite perfusion compared with saline perfusion.

View larger version (19K): [in a new window]   Fig. 9. Time-dependent changes in extracellular [NO2-] after addition of nitrite to red blood cell (RBC) suspensions in a tonometer (A,B). The decrease in extracellular [NO2-] reflects an influx of nitrite into the RBCs. Note the different [NO2-] axes, haematocrits and O2 saturations. N2 and O2 indicate full deoxygenation and oxygenation, respectively. C and D show the corresponding methaemoglobin (metHb) values. See text for further details.