ABSTRACT
Zebrafish are increasingly used as a vertebrate model to study human cardiovascular disorders. Although heart structure and function are readily visualized in zebrafish embryos because of their optical transparency, the lack of effective tools for evaluating the hearts of older, nontransparent fish has been a major limiting factor. The recent development of high-frequency echocardiography has been an important advance for in vivo cardiac assessment, but it necessitates anesthesia and has limited ability to study acute interventions. We report the development of an alternative experimental ex vivo technique for quantifying heart size and function that resembles the Langendorff heart preparations that have been widely used in mammalian models. Dissected adult zebrafish hearts were perfused with a calcium-containing buffer, and a beat frequency was maintained with electrical stimulation. The impact of pacing frequency, flow rate and perfusate calcium concentration on ventricular performance (including end-diastolic and end-systolic volumes, ejection fraction, radial strain, and maximal velocities of shortening and relaxation) were evaluated and optimal conditions defined. We determined the effects of age on heart function in wild-type male and female zebrafish, and successfully detected hypercontractile and hypocontractile responses after adrenergic stimulation or doxorubicin treatment, respectively. Good correlations were found between indices of cardiac contractility obtained with high-frequency echocardiography and with the ex vivo technique in a subset of fish studied with both methods. The ex vivo beating heart preparation is a valuable addition to the cardiac function tool kit that will expand the use of adult zebrafish for cardiovascular research.
Footnotes
Competing interests
The authors declare no competing or financial interests.
Author contributions
Conceptualization: A.V.D.; Methodology: H.Z., A.V.D., X.M.; Software: A.V.D.; Validation: H.Z., A.V.D., I.G.H., C.F.S.; Formal analysis: H.Z., A.V.D., C.F.S.; Investigation: H.Z., A.V.D., I.G.H., X.M., C.F.S.; Data curation: H.Z., A.V.D., I.G.H., X.M., C.F.S., D.F.; Writing - original draft: A.V.D., X.X.; Writing - review & editing: H.Z., A.V.D., I.G.H., D.F., X.X.; Supervision: D.F., X.X.; Project administration: A.V.D., I.G.H., D.F., X.X.; Funding acquisition: D.F., X.X.
Funding
The work was supported by the National Heart, Lung, and Blood Institute (R01HL107304 and R01HL81753 to X.X.), the Mayo Foundation for Medical Education and Research (to X.X.), the National Health and Medical Research Council, the Estate of the Late RT Hall, St. Vincent's Clinic Foundation and the Simon Lee Foundation (to D.F.).
Supplementary information
Supplementary information available online at http://dmm.biologists.org/lookup/doi/10.1242/dmm.034819.supplemental
- Received April 4, 2018.
- Accepted July 10, 2018.
- © 2018. Published by The Company of Biologists Ltd
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.