Differences between store-dependent Ca2+ fluxes in lymphocytes from African Americans and whites.
OBJECTIVE
To investigate differences between store-dependent Ca2+ in African American and white men.


METHODS
Thapsigargin, a potent and specific inhibitor of the sarco(endo)plasmic reticulum Ca(2+)-ATPase, was used as a probe to elicit store-dependent Ca2+ fluxes. Treatment with this agent caused a rise in the cytosolic free Ca2+ due to the egress of Ca2+ from thapsigargin-sensitive Ca2+ stores and the acceleration of external Ca2+ influx through store-dependent Ca2+ channels.


METHODS
Lymphocytes were obtained from 22 African Americans and 23 whites. These cells were subjected to thapsigargin treatment and changes in the cellular Ca2+ profiles were monitored.


RESULTS
Both in Ca(2+)-free and in Ca(2+)-containing media the increases in cytosolic free Ca2+ concentrations after thapsigargin treatment were greater in lymphocytes from African Americans than they were in those from whites. The greater levels of cytosolic Ca2+ concentration were coupled with higher rates of Ca2+ extrusion in thapsigargin-treated lymphocytes from African Americans.


CONCLUSIONS
These findings suggest that store-dependent Ca2+ fluxes are greater in lymphocytes from African Americans than they are in those from whites. This phenomenon increases the Ca2+ turnover rate and might augment the sensitivity to agonists acting through Ca2+ signaling systems, thereby predisposing African Americans to essential hypertension.
Fekete
Z
Z
Hypertension Research Program, University of Medicine and Dentistry of New Jersey-NJ Medical School, USA.
Kimura
M
M
Horiguchi
M
M
Gardner
J P
JP
Nash
F
F
Aviv
A
A
D000328:Adult; D044383:Black People; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D003600:Cytosol / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D012519:Sarcoplasmic Reticulum / Q000201:enzymology; D019284:Thapsigargin / Q000494:pharmacology; D044465:White People; D001741:Black or African American
D004791:Enzyme Inhibitors; D019284:Thapsigargin; D000252:Calcium-Transporting ATPases; D002118:Calcium