PLATELET FREE CALCIUM AND SERUM FREE CALCIUM IN ESSENTIAL HYPERTENSION

Intracellular free calcium of platelets and serum free calcium were studied in human essential hypertension. Intracellular free calcium of platelets was significantly higher in hypertensive patients than that in normotensive subjects, and this was correlated with blood pressure. There was no difference of serum free calcium between hypertensives and normotensive controls. Antihypertensive treatment with nifedipine resulted in a reduction of platelet free calcium, and this was correlated with the fall of blood pressure. In patients treated with clonidine, although there was no difference of platelet free calcium between hypertensives and normotensive controls, serum free clacium was significantly reduced. These results indicated that intracellular free calcium may be regulated by same hormonal or pharmacological factors which determined the height of blood pressure, calcium channel blockers may be more effective in prevention of cardiovascular and cerebrovascular complications caused by platelet hyperfunction in essential hypertension.