Hypertension does not affect intracellular calcium uptake in human platelets

The relationship between the Ca2+ transport of platelet endoplasmic reticulum and hypertension was analyzed in 17 untreated patients exhibiting various degrees of hypertension. Each patient underwent a 24-h recording of ambulatory blood pressure. Platelets from patients were permeabilized with saponin and the rate of ATP-driven thapsigargin-sensitive Ca2+ uptake determined using the fluorescent Ca2+ indicator fluo-3. No relationship between blood pressure (systolic, diastolic, day, night) and the rate of Ca2+ uptake into the sacroplasmic reticulum of platelets was found. A weak but insignificant correlation between Ca2+ uptake and the heart rate was noted. Therefore, the increase in cytosolic Ca2+ of platelets in hypertension may not be due to changes of the activity of Ca2+ uptake into the sacroplasmic reticulum.