[Free calcium in platelets and the serum in essential hypertension].

Intracellular free calcium of platelets was studied in 45 patients with essential hypertension and in 6 patient's normotensive offspring. Intracellular free calcium of platelets in hypertensive patients was significantly higher than those in normotensive subjects (223 +/- 26 vs 170 +/- 28 nmol/lL, P less than 0.001). There was a positive correlation between intracellular free calcium of platelets and blood pressure (r = 0.653 approximately 0.729, P less than 0.001). No increase of intracellular free calcium of platelets was found in patient's normotensive offspring. 33 patients also had serum free calcium measured simultaneously. There was no difference between patients and the normotensive control (1.10 +/- 0.15 vs 1.09 +/- 0.10 mmol/L, P greater than 0.05). However, a positive correlation between serum free calcium and blood pressure (r = 0.363, P less than 0.05) and a weak positive correlation between serum free calcium and intracellular free calcium of platelets (r = 0.337, r 0.05 = 0.344) were found. These results indicated that intracellular free calcium was involved in the regulation of blood pressure, it was postulated that the intracellular free calcium of smooth muscle cell in the peripheral arteriole with resistance might have the similar changes seen in platelets. The changes of intracellular free calcium of platelets might be valuable in the prevention and treatment of hypertension and its vascular complications.