DIFFERENCES IN PLATELET CALCIUM REGULATION BETWEEN AFRICAN-AMERICANS AND CAUCASIANS - IMPLICATIONS FOR THE PREDISPOSITION OF AFRICAN-AMERICANS TO ESSENTIAL-HYPERTENSION

Objective: To study differences in cytosolic free calcium regulation b etween African Americans and Caucasians, using platelets as a model fo r studying cellular physiology. Design: Platelet calcium regulation in apparently healthy African American and Caucasian males was examined. Methods: Using fura-2, calcium influx and cytosolic calcium extrusion were monitored after treatment with thapsigargin, an inhibitor of the Ca-ATPase in the dense tubular membrane system. Results: Compared wit h Caucasians, platelets from African Americans demonstrated a higher c alcium influx into the cytosol (from the external medium and dense tub ular membrane system), as well as enhanced calcium extrusion from the cytosol. Conclusions: Such findings indicate that platelets from Afric an Americans have increased intracellular calcium stores or increased cellular calcium turnover, or both. If these racial differences involv e other cells, such as vascular smooth muscle cells, they could underl ie the predisposition of African Americans to essential hypertension.