Abstract
The ventricle of salmonids is composed of an outer compact layer, routinely supplied with well-oxygenated arterial blood, and inner spongy myocardium receiving low oxygen venous blood. During hypoxia oxygen exposures for both these tissue layers declines. As well, hypoxia results in an increase to circulating epinephrine for trout, which may affect the contractile response during hypoxia. This thesis presents an investigation into effects of high epinephrine, as well, acute and chronic hypoxia exposure on the contractile performance of these ventricular tissues from rainbow trout (Oncorhynchus mykiss). Acute hypoxia resulted in a similar decline to work output in compact and spongy myocardium. High epinephrine however, improved contractile performance of spongy myocardium during hypoxia. Hypoxia acclimation resulted in a decline to work output from spongy myocardium across all oxygen exposures. It appears hypoxia causes a decline in ventricular performance; however, elevated epinephrine exposure may be important to maintain higher performance during hypoxia.
