ADRENERGIC CONTROL OF THE FORCE-FREQUENCY RELATION

This article briefly reviews recent experimental studies which show th at beta-adrenergic receptor stimulation produces an important enhancem ent of the force-frequency relation on myocardial contractility. The b asic property of the force-frequency effect to progressively enhance m yocardial contractility as heart rate increases is augmented at each l evel of increasing adrenergic stimulation. This newly described intrin sic mechanism for the control of cardiac inotropic state, graded beta- adrenergic amplification of the force-frequency relation, is strongly manifested during normal exercise and infusion of a beta-adrenergic ag onist at rest, and it influences both systolic and diastolic ventricul ar function. Significant impairment of adrenergic amplification of the force-frequency relation is observed in experimental heart failure an d could contribute to impaired cardiac function during stress or exerc ise in this setting.