Hormonal modulation of intracellular free calcium in platelets from normotensive and hypertensive subjects.

Sensitivity to adrenaline-antagonism of the inhibitory effect of PGI2 on thrombin-induced increase in [Ca2+]i was measured in platelets from normotensive and untreated hypertensive subjects. Platelets from hypertensive subjects exhibited an increased sensitivity to adrenaline. This effect was more pronounced in younger patients with hypertension, and suggests an increased adenylate cyclase sensitivity in the early hypertension. The data also indicate that a mechanism linked to calcium-influx plays an important role in older hypertensives. This may explain the greater efficacy of calcium entry blockers in older hypertensive patients with essential hypertension.