Increased calcium stores in platelets from African Americans

Area of Science:

• Cardiovascular Research
• Cellular Physiology
• Racial Health Disparities

Background:

• Cation transport differences observed between African Americans and whites may predispose African Americans to essential hypertension.
• Platelets serve as a valuable cellular model for investigating calcium regulation and its role in hypertension.

Purpose of the Study:

• To explore racial differences in calcium regulation using platelets as a cellular model.
• To compare calcium fluxes and cytosolic free calcium levels in platelets from African American and white men.

Main Methods:

• Measured calcium-45 (45Ca) fluxes in platelets from 21 African American and 25 white men.
• Utilized fura 2 to measure cytosolic free calcium levels in resting and stimulated platelets.
• Analyzed platelet 45Ca uptake and washout kinetics, and cytosolic calcium concentrations.

Main Results:

• Platelets from African Americans exhibited larger rapidly and slowly exchangeable 45Ca pools compared to whites.
• Higher 45Ca washout from a rapidly exchangeable pool was observed in African American platelets.
• Resting cytosolic free calcium was lower in African Americans, but sustained levels increased more significantly after ouabain and thrombin stimulation.

Conclusions:

• Platelets from African Americans demonstrate greater intracellular calcium stores than those from whites.
• Observed racial differences in platelet calcium handling could explain African American sensitivity to vasoactive agents.
• These findings suggest a potential cellular mechanism linking race, calcium regulation, and essential hypertension.