Fig 1.
Workflow of routine investigations to measure hemodynamic and cardiac parameters in vivo.
After an anesthesia with 0.04% tricaine, the fish were injected i.p. with 12 μl (1 nmol/L) of the paralyzing agent μ-conotoxin GIIIB (μ-CTX). After paralysis was observed, the fish was adapted to the oral perfusion for 10 min. Thereafter, baseline values have been acquired between t0 and t8. Drug solutions were orally administered with the perfusate at 9.5 min.
Fig 2.
Electrocardiographic (ECG) measurements to validate heart rate (HR) stability during paralysis.
(A) Placement of the electrodes for the ECG. The reference electrode was coupled to the perfusion needle. (B) Optical measurements of HR of non-treated zebrafish (n = 5). The HR remained constant with deviations of less than ±5%. (C) Example of an ECG recorded during stopped oral perfusion. (D) Representative image of plotted PP-intervals in a non-perfused window.
Fig 3.
Optical measurement of heart rates in response to isoprenaline, tricaine and sodium nitroprusside (SNP) in vivo.
The heart rates of the same fish were followed over a period of 30 min at intervals of 2 min. Values obtained between t10 and t30 are expressed as percentage of the baseline (t0-t8). Drug solutions were administered at 9.5 min (indicated by the dashed line).
Fig 4.
Blood velocity and shear stress measurements in the submental vein.
(A) Ventral view of the head of an adult zebrafish. White arrowheads indicate the submental vein. (B) Still image of a 3 second-movie of the blood flow in the submental vein. (C+D) Blood velocity at the inlet and shear stress plotted in percent as deviation from baseline (t0-t8). (C’+D’) Simulations of blood velocity and shear stress performed at the time points designed in C+D.
Fig 5.
Hemodynamic response in the submental vein to application of 50 μmol/L Iso and 1 mmol/L SNP.
Blood flow velocity, shear stress and an example of a numerical simulation of (A) control animals, (B) isoprenaline-treated, and (C) SNP-treated animals. Control fish were observed after 10 min of oral perfusion with system water (“before”) and 10 min later (“after”).