Platelet morphology and plasma indices of platelet activation in essential hypertension: Effects of amlodipine-based antihypertensive therapy

BACKGROUND AND AIM. Platelet abnormalities have been described in hypertension, especially in the presence of target organ damage. Our aim was to study the differences in morphology and indices of platelet activation in treatment-naive patients with essential hypertension as compared to normotensive controls and secondly, to study the effects of amlodipine-based antihypertensive therapy on these indices. METHODS. We recruited 42 previously untreated, newly diagnosed hypertensive patients (25 men; mean age 53 years) for the cross-sectional study, where data were compared with those from 30 normotensive controls (20 men; mean age 57 years). Of the 42 untreated hypertensive patients who were recruited, 27 patients successfully completed, the six-month treatment phase with amlodipine-based antihypertensive therapy. Platelet morphology (volume and mass) was quantified, and plasma markers of platelet activation (βTG and sPsel) measured in citrated plasma. The mass of P-selectin in each platelet (pPsel) was determined by lysing a fixed number of platelets and then determining the levels of P-selectin in the lysate. RESULTS. Hypertensive patients had significantly higher platelet volume (P = 0.01) and mass (P = 0.003), plasma βTG and sPsel, and pPsel levels (all P < 0.001) compared to the controls. After a mean treatment time of 6 months, there was a decrease in platelet volume (P < 0.001) and mass (P = 0.02), with lower pPsel, sPsel and BTG levels (all P < 0.001) compared to the untreated state. CONCLUSION. Treatment of uncomplicated essential hypertension using amlodipine-based anti-hypertensive therapy results in a reversal of the platelet morphology abnormalities and indices of platelet activation. This may contribute to a reduction in thrombosis-related complications seen in those whose blood pressure lowering is effective.