ABSTRACT
Heart muscle is an efficeint energy converter. It derives the bulk of its energy for contraction from oxidative phosphorylation of ADP. In this system the transfer of energy is, in turn, tied to oxidative metabolsim of energy-producing substrates. In broader terms, and for all practical purposes, there is no life without oxygen. What applies to the body as a whole, applies even more to the heart. The heart is well designed, both anatomically and biochemically, for uninterrupted, rhythmic aerobic work. In short, the heart makes a living by liberating energy from different oxidizable substrates. Although under resting conditions and in the fasted state, the heart prefers fatty acids as its fuel for respiratio, the heart readily switches to carbohydrates when stressed or when supplied with glucose, insulin and potassium. In short, there is considerable flexibility in the system of energy substrate metabolism of the heart, as the heart responds to changes in the physiological state.
