Abstract
OBJECTIVETo investigate differences between store-dependent Ca in African American and white men.
METHODThapsigargin, a potent and specific inhibitor of the sarco(endo)plasmic reticulum Ca-ATPase, was used as a probe to elicit store-dependent Ca fluxes. Treatment with this agent caused a rise in the cytosolic free Ca due to the egress of Ca from thapsigargin-sensitive Ca stores and the acceleration of external Ca influx through storedependent Ca channels.
DESIGNLymphocytes were obtained from 22 African Americans and 23 whites. These cells were subjected to thapsigargin treatment and changes in the cellular Ca profiles were monitored.
RESULTSBoth in Ca-free and in Ca-containing media the increases in cytosolic free Ca concentrations after thapsigargin treatment were greater in lymphocytes from African Americans than they were in those from whites. The greater levels of cytosolic Ca concentration were coupled with higher rates of Ca extrusion in thapsigargintreated lymphocytes from African Americans.
CONCLUSIONSThese findings suggest that store-dependent Ca fluxes are greater in lymphocytes from African Americans than they are in those from whites. This phenomenon increases the Ca turnover rate and might augment the sensitivity to agonists acting through Ca signaling systems, thereby predisposing African Americans to essential hypertension.