[Autonomic nervous system in heart failure].
The autonomic nervous system (ANS), a complex and self-organized entity, plays a crucial role in cardiovascular regulation. In this review, the authors describe some concepts of anatomo-physiology and cellular/molecular biology of the ANS and of its two major components, the parasympathetic and sympathetic system, both in the normal individual and in the patient with heart failure. Adrenergic and cholinergic neurotransmission, neurotransmitters, adrenergic and cholinergic receptors and intracellular signal transduction are discussed. Some aspects of sympathetic-parasympathetic interaction at the cellular level are described as well as the opposite role of two cyclic nucleotides, cyclic adenosine and guanosine monophosphate. Major emphasis is placed on the beta-adrenergic system, the combination of the beta receptor, G protein complex and adenylyl cyclase. The activation of neurohumoral compensatory mechanisms in heart failure is discussed as well as the increasingly recognized importance of sympathetic overactivation and parasympathetic tonus reducting in this setting. Cellular mechanisms of adrenergic stimulation in heart failure and its consequences are presented, with special focus on down-regulation of beta-1 adrenergic receptors; the authors analyze the steps of phosphorlation and oncoupling, sequestration, internalization and lysosomal degradation, the main result of which is reduced response to catecholamines.
Campelo
Manuel
M
Serviço de Cardiologia, Faculdade de Medicina do Porto, Porto, Portugal. mcampelo@mail.telepac.pt
Abreu-Lima
Cassiano
C
D001341:Autonomic Nervous System / Q000503:physiopathology*; D006333:Heart Failure / Q000503:physiopathology*; D006801:Humans