|
|
|
|||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
First published online June 29, 2007
Journal of Experimental Biology 210, 2574-2584 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.004028
Cardiac remodelling in rainbow trout Oncorhynchus mykiss Walbaum in response to phenylhydrazine-induced anaemia
Department of Biological Sciences, 8888 University Drive, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
* Author for correspondence at present address: Department of Zoology and Faculty of Land and Food Systems, 6270 University Boulevard, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada (e-mail: farrellt{at}interchange.ubc.ca)
Accepted 2 May 2005
We examined the nature, extent and timing of cardiac ventricular
remodelling in response to chronic, chemically induced anaemia in warm- and
cold-acclimated rainbow trout Oncorhynchus mykiss. Chronic anaemia
was induced by bi-weekly injections of phenylhydrazine hydrochloride (PHZ) and
resulted in transient but large decreases in haematocrit (Hct) and haemoglobin
concentration. After 2 weeks of anaemia, relative ventricular mass
(rMV) in warm-acclimated rainbow trout had already
increased significantly and, by the eighth week of anaemia,
rMV was 58% greater than in the sham-injected control
fish. Temperature modulated the anaemia-induced ventricular remodelling and
erythropoietic responses, as indicated by cold-acclimation reducing the extent
of the cardiac remodelling and slowing erythropoietic recovery. For example,
in cold-acclimated fish, PHZ reduced Hct to 8.8±1.9% (ranging from
416%) and increased rMV by 15% over a 4-week
period, whereas the same treatment in warm-acclimated fish reduced Hct to only
17.4±2.1% (ranging from 629%) and yet increased
rMV by 28%. Cold-acclimated fish also recovered more
slowly from anaemia. In addition, warm-acclimated fish maintained compact
myocardium between 32% and 37% during anaemia, while cold-acclimated fish
responded with an increase in compact myocardium (from 29% to 37%). Routine
cardiac output (
) was continuously
monitored following a single PHZ injection to examine the initial cardiac
response to anaemia. Contrary to expectations, acute anaemia did not produce
an immediate, proportionate increase in routine
. In fact,
did not increase significantly until
Hct had decreased to 10%, suggesting that rainbow trout may initially rely on
venous oxygen stores to compensate for a reduced arterial oxygen-carrying
capacity. Thus, we conclude that myocardial oxygenation, acclimation
temperature and cardiac work load could all influence anaemia-induced cardiac
remodelling in rainbow trout.
Key words: cardiac remodelling, compact myocardium, anaemia, temperature acclimation, heart