Meeting Abstract

P3.223  Sunday, Jan. 6  Functional and morphological changes in the trout heart during thermal acclimation KLAIMAN, J.M.*; PYLE, W.G.; GILLIS, T.E; University of Guelph; University of Guelph; University of Guelph jklaiman@uoguelph.ca

Rainbow trout remain active in waters that seasonally change between 4°C and 20°C. We have previously shown that when male trout are thermally acclimated to the extremes of this temperature range two distinctive cardiac phenotypes emerge. Cardiac hypertrophy is observed in the cold (4°C) acclimated fish with a concurrent increase in connective tissue and a decrease in the thickness of the compact myocardium. Conversely, warm acclimation (17°C), causes a decrease in the amount of connective tissue and an increase in the thickness of the compact myocardium. The opposing effects of cold and warm acclimation suggest that male trout can reversibly remodel the morphology and cellular composition of the heart. This makes the myocardium extremely plastic to changes in environmental temperature. However, how such changes influence the compliance and performance of the trout heart is not yet understood. Here we use a Langendorff preparation to measure how thermal acclimation and the subsequent cardiac remodeling affects the contractility of the isolated trout heart. Briefly, an isolated trout heart is perfused with a modified Krebs-Henseleit buffer using a peristaltic pump. A fluid filled balloon, connected to a pressure transducer, is implanted into the ventricle of the heart via the bulbous. Using this method we are able to measure maximum systolic and end diastolic pressure. By characterizing the passive and active properties of hearts from thermally acclimated trout this study is providing novel perspective into the ability of the vertebrate heart to remodel in response to a physiological stressor.