Altered beta-adrenergic receptor gene regulation and signaling in chronic heart failure

Beta adrenergic receptors (beta -ARs) are critical regulators of cardiac Function in both normal and pathophysiological states. Under normal conditions, beta -ARs and their signaling pathways modulate both the rate and force of myocardial contraction and relaxation. allowing individuals to respond appropriately to physiological stress or exercise, However, in chronic heart failure. sustained activation of the beta -AR signaling pathways can have overtly negative biological consequences. This notion is reinforced by the positive outcomes of a number of clinical trials demonstrating the usefulness of betablocker therapy in chronic congestive heart failure. During the last few years, significant progress has been made in understanding the molecular biological basis of beta -AR Function, both at the biochemical and genetic levels. In this review, the biological basis of adrenergic signaling and how this changes in heart failure is discussed. Aspects of adrenergic receptor pharmacology relevant to heart failure are reviewed, including the recently emerging differences described for beta (1)- v beta (2)-AR signaling pathways. Highlighting these differences is recent evidence that over-stimulation of the beta (1)-AR pathway in cardiac myocytes appears to be pro-apoptotic. whereas stimulation of the beta (2)-AR pathway may be anti-apoptotic. Overview of beta -AR gene regulation, transgenic models of beta -AR overexpression. and beta -AR polymorphisms as they relate to heart failure progression are also discussed. (C) 2001 Academic Press.