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Reversible decrease of surface beta 2-adrenoceptor number and response in lymphocytes of patients with
1Hypertension Research Unit, Hospital Clinic i Provincial, Barcelona, Catalonia, Spain.
Summary
Chronic high catecholamines, like epinephrine, reduce beta 2-adrenoceptor density and response in lymphocytes. This effect is reversible after tumor removal, highlighting catecholamine
Area of Science:
- Endocrinology
- Pharmacology
- Cell Biology
Background:
- Elevated plasma catecholamines are associated with various physiological changes.
- Understanding the impact of chronic catecholamine excess on cellular receptors is crucial for disease management.
Purpose of the Study:
- To investigate the effect of chronic elevated plasma catecholamines on surface beta 2-adrenoceptor density and function.
- To determine the reversibility of these changes after normalization of catecholamine levels.
Main Methods:
- Measured beta 2-adrenoceptor density on lymphocytes using [3H]-CGP12177 binding assays.
- Assessed lymphocyte beta 2-adrenergic response via isoproterenol-stimulated cAMP increase.
- Compared receptor density and response in patients with pheochromocytoma versus healthy controls.
Main Results:
- Patients with pheochromocytoma exhibited significantly reduced beta 2-adrenoceptor density and isoproterenol-stimulated cAMP response.
- These parameters normalized four weeks after tumor removal and normalization of plasma catecholamine levels.
- A strong inverse correlation was observed between plasma epinephrine levels and beta 2-adrenoceptor density.
Conclusions:
- Chronic excess of catecholamines, particularly epinephrine, leads to a reversible decrease in lymphocyte beta 2-adrenoceptor number and function.
- Normalization of plasma catecholamine levels restores beta 2-adrenoceptor density and response.
- Norepinephrine may also contribute to this regulation at very high concentrations.