Molecular Adaptive Mechanisms in the Cardiac Muscle of Exercised Fish

Abstract

This chapter reviews the current knowledge on molecular adaptive mechanisms in the cardiac muscle in response to swimming-induced exercise. Although an impressive and fruitful effort has been committed in the last 50 years to understand the cardiovascular and systemic effects that exercise training produces in fish, very little is known regarding the molecular adaptive mechanisms behind these effects. We present and discuss available information related to mRNA and protein expression adaptations that may further substantiate the exercise training benefits to the cardiac system in fish. In particular, we review molecular mechanisms related to cardiac growth, contractility, energy metabolism, vascularization, and hematopoiesis. In light of the intriguing benefits of exercise training to improve disease resistance in fish, we present an overview of exercise-induced cardiac immune adaptations including inflammatory, complement, and tissue protective responses. Altogether, exercise training seems to promote molecular adaptations that strengthen the overall cardiac capacity and immune competence.