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Venous hemodynamic responses to acute temperature increase in the rainbow trout (Oncorhynchus mykiss)

Journal article
Authors Erik Sandblom
Michael Axelsson
Published in American Journal of Physiology - Regulatory, Integrative and Comparative Physiology
Volume 292
Issue 6
Pages 2292-2298
ISSN 1522-1490
Publication year 2007
Published at Department of Zoology
Pages 2292-2298
Language en
Links dx.doi.org/10.1152/ajpregu.00884.20...
Keywords cardiac performance, cardiac preload, stroke volume, venous capacitance, 51Chromium
Subject categories Biological Sciences, Animal physiology

Abstract

Many ectotherms regularly experience considerable short-term variations in environmental temperature, which affects their body temperature. Here we investigate the cardiovascular responses to a stepwise acute temperature increase from 10 to 13 and 16°C in rainbow trout (Oncorhynchus mykiss). Cardiac output increased by 20 and 31% at 13 and 16°C, respectively. This increase was entirely mediated by an increased heart rate (fH), whereas stroke volume (SV) decreased significantly by 20% at 16°C. The mean circulatory filling pressure (MCFP), a measure of venous capacitance, increased with temperature. Central venous pressure (Pven) did not change, whereas the pressure gradient for venous return (MCFP-Pven) was significantly increased at both 13 and 16°C. Blood volume, as measured by the dilution of 51Cr-labeled red blood cells, was temperature insensitive in both intact and splenectomized trout. This study demonstrates that venous capacitance in trout decreases, but cardiac filling pressure as estimated by Pven does not change when cardiac output increases during an acute temperature increase. SV was compromised as fH increased with temperature. The decreased capacitance likely serves to prevent passive pooling of blood in the venous periphery and to maintain cardiac filling pressure and a favorable pressure gradient for venous return.

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