Platelet activation after adrenergic stimulation in hypertensive patients: effects of acebutolol

In 12 patients with arterial hypertension (stages I and II according to WHO), adrenergic stimulation was induced by the immersion of a hand in ice water for 2 min. Blood samples were withdrawn before, at the end of, and 15 min after the cold application: the experiment was repeated 2 h after the ingestion of 200 mg acebutolol, a selective betablocking agent. The following assays were performed: serum nonesterified fatty acid (NEFA), plasma beta-thromboglobulin (BTG) and PF4 with specific radioimmunoassays; thromboxane B2 (TXB2) in plasma was also estimated with radioimmunoassay, platelet sensitivity to exogenous prostacyclin; furthermore, the thrombin-induced thromboxane production before and after acebutolol ingestion as well as serum TXB2-levels were measured. The blood pressure and the heart rate were also monitored. After cold stimulation, a significant increase of NEFA, BTG, and plasma TXB2 was observed, which was still discernible 15 min after the application of cold. After acebutolol, the cold treatment led to a lower increase of blood pressure with a reduction of the heart rate, as well as to a diminished release of BTG, PF4 and TXB2 no changes in the reduced platelet sensitivity to prostacyclin were noticed.