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First published online December 10, 2003
Journal of Experimental Biology 207, 195-201 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.00742

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Intrinsic autoregulation of cardiac output in rainbow trout (Oncorhynchus mykiss) at different heart rates

Jordi Altimiras^* and Michael Axelsson

Department of Zoology, University of Göteborg, Box 463, S-405 30 Göteborg, Sweden

View larger version (39K): [in a new window]   Fig. 1. Anatomical details of the surgical implantation of a cannula in the sinus venosus. (A) Schematic drawing showing the position of insertion in the Vth gill arch. (B) Picture showing the thin-walled left duct of Cuvier (LDC) bulging from the incision site. (C) Picture showing the two silk snares in place before the cannulation. The tied snare (top one) is used to pull the vessel wall during the procedure, the untied snare (bottom one) is used to secure the cannula to the LDC after insertion.

View larger version (10K): [in a new window]   Fig. 2. Dose-response curve of the effect of zatebradine (ZAT) on heart rate fH. An arrow indicates [ZAT]0.5, the concentration of zatebradine at which heart rate was half the control value. Values are means ± S.E.M. (N=14).

View larger version (9K): [in a new window]   Fig. 3. Effect of zatebradine (ZAT) (dose equivalent to the Km for each individual fish; see Materials and Methods) on (A) dorsal aortic pressure (PDA), (B) peripheral resistance (Rsys), (C) heart rate (fH), (D) relative cardiac output () and (E) relative stroke volume (VS). Values are means ± S.E.M. (N=14). Asterisks indicate significant difference from the control value (P<0.05).

View larger version (12K): [in a new window]   Fig. 4. Effect of different doses of zatebradine on heart rate and venous pressure in vivo. Values are means ± S.E.M. (N=10). Asterisks indicate significant difference from the control value (P<0.05).

View larger version (22K): [in a new window]   Fig. 5. Time-dependent effects of zatebradine (1 mg ml-1) on heart rate (fH) and preload pressure (Pin) in the perfused heart. Zatebradine-perfused hearts (closed symbols, N=5) are shown together with control perfused hearts (open symbols, N=4) to account for the possible deterioration of the preparation over time. Values are means ± S.E.M.

View larger version (21K): [in a new window]   Fig. 6. Relationship between heart rate (fH) and preload pressure (Pin), cardiac output (), power output of the heart (mW g-1)and stroke volume (VS) in the hearts perfused with Ringer saline and zatebradine (1 mg ml-1). Values are means ± S.E.M. (N=5). Asterisks indicate significant difference from the control value (at 60 beats min-1) (P<0.05).