Journal of Comparative Physiology B

, Volume 171, Issue 8, pp 623–633 | Cite as

The effects of endothelin-1 on the cardiorespiratory physiology of the freshwater trout (Oncorhynchus mykiss) and the marine dogfish (Squalus acanthias)

  •  S. Perry
  •  C. Montpetit
  •  J. McKendry
  •  P.R. Desforges
  •  K. Gilmour
  •  C. Wood
  •  K. Olson
Original paper

Abstract.

The aim of the present study was to evaluate the effects of endothelin-1-elicited cardiovascular events on respiratory gas transfer in the freshwater rainbow trout (Oncorhynchus mykiss) and the marine dogfish (Squalus acanthias). In both species, endothelin-1 (666 pmol kg–1) caused a rapid (within 4 min) reduction (ca. 30–50 mmHg) in arterial blood partial pressure of O2. The effects of endothelin-1 on arterial blood partial pressure of CO2 were not synchronised with the changes in O2 partial pressure and the responses were markedly different in trout and dogfish. In trout, arterial CO2 partial pressure was increased transiently by ~1.0 mmHg but the onset of the response was delayed and occurred 12 min after endothelin-1 injection. In contrast, CO2 partial pressure remained more-or-less constant in dogfish after injection of endothelin-1 and was increased only slightly (~0.1 mmHg) after 60 min. Pre-treatment of trout with bovine carbonic anhydrase (5 mg ml–1) eliminated the increase in CO2 partial pressure that was normally observed after endothelin-1 injection. In both species, endothelin-1 injection caused a decrease in arterial blood pH that mirrored the changes in CO2 partial pressure. Endothelin-1 injection was associated with transient (trout) or persistent (dogfish) hyperventilation as indicated by pronounced increases in breathing frequency and amplitude. In trout, arterial blood pressure remained constant or was decreased slightly and was accompanied by a transient increase in systemic resistance, and a temporary reduction in cardiac output. The decrease in cardiac output was caused solely by a reduction in cardiac frequency; cardiac stroke volume was unaffected. In dogfish, arterial blood pressure was lowered by ~10 mmHg at 6–10 min after endothelin-1 injection but then was rapidly restored to pre-injection levels. The decrease in arterial blood pressure reflected an increase in branchial vascular resistance (as determined using in situ perfused gill preparations) that was accompanied by simultaneous decreases in systemic resistance and cardiac output. Cardiac frequency and stroke volume were reduced by endothelin-1 injection and thus both variables contributed to the changes in cardiac output. We conclude that the net consequences of endothelin-1 on arterial blood gases result from the opposing effects of reduced gill functional surface area (caused by vasoconstriction) and an increase in blood residence time within the gill (caused by decreased cardiac output.

Catecholamines Cardiac output Ventilation Endothelin-1 Carbonic anhydrase 

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Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  •  S. Perry
    • 1
  •  C. Montpetit
    • 1
  •  J. McKendry
    • 1
  •  P.R. Desforges
    • 1
  •  K. Gilmour
    • 2
  •  C. Wood
    • 3
  •  K. Olson
    • 4
  1. 1.Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, Ontario, Canada K1N 6N5
  2. 2.Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6
  3. 3.Department of Biology, McMaster University, 1280 Main Street W., Hamilton, Ontario, Canada L8S 4K1
  4. 4.Indiana University School of Medicine, South Bend Center, University of Notre Dame, Notre Dame, IN 46556-5607, USA

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