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Enforced exercise, but not acute temperature elevation, decreases venous capacitance in the stenothermal Antarctic fish Pagothenia borchgrevinki

Journal article
Authors Erik Sandblom
Michael Axelsson
W. Davison
Published in Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
Volume 178
Issue 7
Pages 845-851
ISSN 0174-1578
Publication year 2008
Published at Department of Zoology
Pages 845-851
Language en
Links dx.doi.org/10.1007/s00360-008-0272-...
Keywords Antarctic, Exercise, Fish, Mean circulatory filling pressure, Temperature
Subject categories Animal physiology

Abstract

The venous haemodynamic response to enforced exercise and acute temperature increase was examined in the Antarctic fish Pagothenia borchgrevinki (borch) to enable comparisons with the existing literature for temperate species, and investigate if the unusual cardiovascular response to temperature changes previously observed in the borch can be linked to an inability to regulate the venous vasculature. Routine central venous blood pressure (P cv) was 0.08 kPa and the mean circulatory filling pressure (P mcf; an index of venous capacitance) was 0.14 kPa. Acute warming from 0 to 2.5 and 5°C increased heart rate (f H), while dorsal aortic blood pressure (P da) decreased. P mcf did not change, while P cv decreased significantly at 5°C. This contrasts with the venoconstriction previously observed in rainbow trout in response to increased temperature. Exercise resulted in small increases in P mcf and P cv, a response that was abolished by α-adrenoceptor blockade. This study demonstrates that the heart of P. borchgrevinki normally operates at positive filling pressures (i.e. P cv) and that venous capacitance can be actively regulated by an α-adrenergic mechanism. The lack of decrease in venous capacitance during warming may suggest that a small increase in venous tone is offset by a passive temperature-mediated increase in compliance.

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