Key result
Chronic beta-blockade induced a time-dependent reduction of alpha2-adrenergic receptors and Gi proteins, resulting in reduced catecholamine-induced activation and aggregation of human platelets.
Why the study?
Does chronic beta-blockade transregulate the expression of alpha2-adrenergic receptors on human platelets and modulate platelet activation in healthy volunteers?
Observational
Does chronic beta-blockade transregulate the expression of alpha2-adrenergic receptors on human platelets and modulate platelet activation in healthy volunteers?
Chronic beta-blockade reduces alpha2-adrenergic receptor density and function on platelets, impairing platelet activation, which provides a mechanistic explanation for its therapeutic benefits in coronary heart disease.
May attenuate platelet reactivity in coronary disease; leaves open clinical translation from this in vitro evidence.
Platelets play a pivotal role in the pathophysiology of acute coronary syndromes. Chronic beta-blockade has been shown to improve the long-term clinical outcome in coronary heart disease. Because platelets play a central role in thrombus formation, the aim of the present study was to investigate if chronic beta-blockade may transregulate the expression of alpha2-adrenergic receptors on human platelets and via this mechanism may modulate platelet activation. The densities of alpha2-adrenergic receptors of platelets were determined in healthy volunteers under chronic beta-blockade and as alpha2-adrenergic receptor-mediated function in catecholamine-induced platelet aggregation was determined. Chronic beta-blockade induced a time-dependent reduction of alpha2-adrenergic receptors. This reduction was accompanied by a decrease of the alpha-subunit of Gi proteins as demonstrated by Western blot analysis. This transregulation at both the receptor level and the G-protein level resulted in an almost complete loss of the alpha2-adrenergic receptor-mediated inhibition of adenylyl cyclase. The impairment of the alpha2-adrenergic receptor system correlated with a reduction of the catecholamine-induced activation and aggregation of human platelets. The functional transregulation of alpha2-adrenergic receptors by chronic beta-blockade in platelets and the consequent impairment of platelet activation may contribute to the therapeutic success of beta-blocker therapy.
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Schwencke et al. (2005) conducted an observational in Healthy volunteers. Chronic beta-blockade was evaluated on Densities of alpha2-adrenergic receptors and catecholamine-induced platelet aggregation. Chronic beta-blockade induced a time-dependent reduction of alpha2-adrenergic receptors and Gi proteins, resulting in reduced catecholamine-induced activation and aggregation of human platelets.
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