Summary
Blood platelet function was evaluated in 10 men, all 50 years old, with untreated,
mild hypertension. Each patient was examined four times: At the beginning of the study,
after 5 weeks on placebo treatment, after the following 5 weeks on propranolol 160
mg daily, and finally after a second period of 5 weeks on placebo. At baseline the
plasma level of the platelet release product (β-thromboglobulin (BTG) was 41.6 (30.5-57.0)
μg/l (median and 95% confidence interval). During the first placebo period BTG was
normalized to 21.0 (14.1-25.9) μg/l. While systolic blood pressure and heart rate
fell during β-adrenergic receptor blockade, BTG remained unchanged throughout the
rest of the observation periods. Platelet size increased significantly during treatment
with β-blocker. The present study indicates that the normalization of elevated platelet
function which previously has been reported to occur during anti-hypertensive drug
therapy, may be explained by patient adaptation to the blood sampling procedure.
Keywords
β-thromboglobulin - Blood pressure - Platelet size - Catecholamines - β-blocker -
Thrombocytopoiesis
