EFFECT OF CYTOKINES ON CYTOSOLIC-FREE CALCIUM IN HUMAN PLATELETS FROMESSENTIAL HYPERTENSIVES

The different effects of cytokines on cytosolic-free calcium concentra tion ([Ca2+]i) and intracellular stored calcium were investigated in p latelets from 35 essential hypertensive patients (HT) and 45 age- and sex-matched normotensive control subjects (NT). Erythropoietin (EPO) a nd interleukin 2 significantly increased platelet [Ca2+]i, whereas pla telet-derived growth factor, and fibroblast growth factor had no signi ficant effect on [Ca2+]i. The EPO-induced rise of [Ca2+]i was signific antly higher in HT compared to NT (15.2 +/- 4.3 nmol/L v 1.3 +/- 1.7 n mol/L, P < .01). Preincubation with EPO significantly increased calciu m in intracellular stores in platelets from HT and NT. Inhibition of p rotein kinase C significantly enhanced EPO-induced rise of stored calc ium. It is concluded that an increased response of HT to EPO may be as sociated with essential hypertension.