[Mechanisms of the regulation of adrenergic beta-receptors]

Adrenaline and noradrenaline exert their effects via specific adrenergic receptors. Of the nine known subtypes of these receptors, the beta 1-subtype mediates an increase in cardiac contractility, while the beta 2-subtype is responsible for vasodilatation. These receptors are not just simple signal transducers but components of a complex and highly regulated signalling machinery. A loss of sensitivity of this machinery may be induced by exogenous as well as endogenous stimuli (= desensitisation). Desensitisation of cardiac beta-adrenergic receptors may contribute to contractile dysfunction in chronic heart failure.