Is the teleost heart oxygen limited? – Insights using “hyperoxic” incubations of contracting cardiac tissue from rainbow trout

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Considerable effort has been devoted to understanding the negative effects of reduced PO 2 on cardiac function. Much less is known about the impacts of elevated PO 2 (hyperoxia) on cardiac performance and energetics, especially in fishes. The fish heart is of particular interest because cardiac dependence on oxygen is extremely variable between species and the early evolution of fish occurred when atmospheric PO 2 was higher than current conditions. Although extracellular PO 2 is variable and normally does not exceed 21 kPa, recent evidence suggests that teleost cardiac function is stimulated at supraphysiological PO 2 values. The purpose of this study was to address whether cardiac contractility and energy metabolism is responsive to elevated PO 2 values in sexually-immature female rainbow trout. Isometric force development (contractility) and oxygen consumption (V̇O 2 ) were recorded in electrically-paced ventricular preparations. Contractility and V̇O 2 decreased when superfusate PO 2 was decreased from ~70 kPa to 57 kPa or 45 kPa. However, PO 2 calculated at the preparation core was always above 18 kPa. This estimate, along with complete recovery of contractility and V̇O 2 at ~70 kPa, suggests that decreases observed in cardiac performance were not due to tissue hypoxia at the lower PO 2 levels. In conclusion, the heart of female rainbow trout may be oxygen-limited in vitro and this study raises new questions about the choice of appropriate PO 2 for experimentation, the relevance of elevated and varying PO 2 to measurements of cardiac performance, and the possible existence of an oxygen sensor within rainbow trout cardiomyocytes.

Original languageEnglish
JournalComparative Biochemistry and Physiology -Part A : Molecular and Integrative Physiology
Volume231
Pages (from-to)124-130
Number of pages7
ISSN1095-6433
DOIs
Publication statusPublished - 1 May 2019

    Research areas

  • Cardiac performance, Force development, Oxygen, Oxygen consumption, Rainbow trout

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