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Effects of hypoxia on the venous circulation in rainbow trout (Oncorhynchus mykiss)

Journal article
Authors Erik Sandblom
Michael Axelsson
Published in Comparative Biochemistry and Physiology a-Molecular & Integrative Physiology
Volume 140
Issue 2
Pages 233-239
ISSN 1095-6433
Publication year 2005
Published at Department of Zoology
Pages 233-239
Language en
Keywords hypoxia, hypoxic bradycardia, total peripheral resistance, venous pressure, venous pooling, cardiac-output, blood-pressure, gadus-morhua, atlantic cod, heart-rate, fish, performance, exercise, flow
Subject categories Biological Sciences

Abstract

Hypoxia in fish is generally associated with bradycardia while cardiac output (Q) remains unaltered or slightly increased due to a compensatory increase in stroke volume (SV). Rainbow trout (Oncorhynchus mykiss) were subjected to severe (PWO2=7.3 +/- 0.2 kPa) or mild (PWO2=11.5 +/- 0.2 kPa) hypoxia. Central venous pressure (P-ven), dorsal aortic pressure (P-da), heart rate (f(H)) and Q, were recorded in vivo. Both levels of hypoxia triggered a significant increase in P-ven. Severe hypoxia was associated with bradycardia and unaltered Q, whereas mild hypoxia was associated with a small but significant increase in Q and no bradycardia. These findings indicate that an increase in P-ven, promotes an increase in SV during hypoxia. Since mild hypoxia increased P-ven, Q and SV without bradycardia or reduced systemic resistance (R-sys), we hypothesize that an active increase in venous tone serving to mobilize blood to the central venous compartment in order to increase cardiac preload and consequently SV, is an important cardiovascular trait associated with hypoxia. Pharmacological pre-treatment with prazosin (1 mg kg(-1)) did not conclusively reveal the underlying mechanisms to the observed changes in P-ven. This study discusses the influence of venous pooling, reduced R-sys and altered venous tone on changes in P-ven observed during hypoxia. (c) 2005 Elsevier Inc. All rights reserved.

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