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[Beta adrenergic receptors in circulating lymphocytes of patients with chronic heart failure]
E Guarda1, R Corbalan, S Lavandero
1Departamento de Enfermedades Cardiovasculares, Pontificia Universidad Católica de Chile, Santiago de Chile.
Insights
Patients with chronic heart failure have fewer beta-adrenergic receptors on lymphocytes. This decrease in beta receptors may be linked to higher circulating catecholamines, especially during exercise.
Area of Science:
- Cardiology
- Molecular Biology
- Pharmacology
Context:
- Chronic heart failure (CHF) is characterized by neurohormonal dysregulation.
- Elevated circulating catecholamines and reduced myocardial beta-adrenergic receptors are hallmarks of severe CHF.
- Lymphocytes serve as a surrogate for studying adrenergic receptor density in vivo.
Purpose:
- To investigate the density of beta-adrenergic receptors and cyclic AMP (cAMP) levels in circulating lymphocytes of patients with stable, class II-III heart failure.
- To compare these values with those of healthy controls.
Summary:
- This study examined 14 patients with stable heart failure and 10 healthy controls.
- Results showed a significant reduction in the number of beta-adrenergic receptors on lymphocytes in heart failure patients (105 +/- 16 fmol/mg protein) compared to controls (185 +/- 24 fmol/mg protein, p < 0.01).
- No significant differences were observed in the dissociation constant (Kd) or intracellular cAMP levels between the groups.
Impact:
- The findings suggest that decreased beta-adrenergic receptor density on circulating lymphocytes is a feature of stable heart failure.
- This reduction may be associated with elevated circulating catecholamines, potentially exacerbated during physical activity.
- Understanding these alterations can inform therapeutic strategies targeting the adrenergic system in heart failure management.
Abstract:
Severe decompensated chronic heart failure is associated to increased levels of circulating catecholamines and decreased density of myocardial beta-adrenergic receptors. In 14 patients with stable, class II-III heart failure we studied circulating lymphocytes to determine the number of beta adrenergic receptors, the dissociation constant of 3H dihydroalprenolol (kd) and the intracellular content of cyclic AMP (AMPc). Results (mean +/- SEM) were compared to those obtained in 10 healthy controls. The number of beta receptors was significantly decreased (105 +/- 16 vs 185 +/- 24, fmol/mg of membrane protein, p less than 0.01). No differences were found in Kd (1.65 +/- 0.2 vs. 1.36 +/- 0.28 nm) nor the level of AMPc (7.9 +/- 2.1 vs 7.1 +/- 2.9 pmol/mg protein), respectively. The decreased number of beta adrenergic receptors in the circulating lymphocytes may be related to the increased level of circulating catecholamines that have been shown to be present during exercise in these patients.