Regulation of energy consumption in the cardiac muscle

The biochemical-mechanical basis for the well known linear relationship between left ventricular (LV) oxygen consumption and generated mechanical energy is established here. Biochemical studies and the analysis of calcium kinetics suggest a positive feedback mechanism, the cooperativity, whereby the affinity of the regulatory proteins for calcium depends on the number of force producing crossbridges (Xbs). The mechanical energy, quantified by the force-length area (FLA) or by the force-time integral (FTI) for isometric regime is in excellent correlation with the calculated energy consumption. The cooperativity regulates crossbridge ATPases recruitment, hence the rate of energy consumption and the generated force, thus providing the molecular basis for the regulation of cardiac muscle economy.