Meeting Abstract
P1.82 Saturday, Jan. 4 15:30 Temperature Dependent Cardiac Remodeling in the Rainbow Trout (Oncorhynchus mykiss) KEEN, Adam N*; GARDNER, Peter; SHIELS, Holly A; Univ. of Manchester; Univ. of Manchester; Univ. of Manchester adam.keen@manchester.ac.uk
The heart will remodel under stressful circumstances to maintain an optimal cardiac output and appropriate pressure volume relationships. The ectothermic nature of fish means the heart will remodel seasonally. Cold temperature induces a pressure-overload hypertrophy and fibrosis of cardiac muscle, while warm temperature causes atrophy of cardiac tissue and a reduction in collagen fibre density. The effect of remodeling on cardiac compliance, structure and tissue biochemistry was studied in fish acclimated to 3 temperatures (5, 10 and 18° C), to simulate seasonal temperature fluctuation, on which 3 experimental techniques were then used: generation of pressure volume curves, tissue histology and tissue FTIR spectroscopy. Temperature acclimation had no effect on the cardiac compliance of the ventricle or the outflow tract (OFT), however, there did appear to be an alteration in atrial compliance. Temperature did not affect heart chamber morphology, but collagen density increased in the cold acclimated group, especially in the compact layer of the ventricle. Finally, FTIR spectra showed temperature dependent changes in amide I and amide II absorption bands indicating an increase in protein in the ventricle, a decrease in the OFT and the atrium remaining constant after cold acclimation. The conclusions agree with recent work suggesting temperature acclimation does not affect ventricular filling volume or pressure in addition to showing a remodeling response in the atrium and OFT as well as the ventricle, both of which have until recently been overlooked. Finally, we show the potential of FTIR to determine alterations in protein and metabolic state of fish cardiac tissue as well as suggesting changes in the underlying chemistry of the tissue may arise before morphological or physiological changes during cardiac remodeling.
