Ca2+ transport in unstimulated platelets of essential hypertensives and their blood relatives.
OBJECTIVE
Intracellular free Ca2+ concentration has been shown to be elevated in platelets from essential hypertensive patients. This study was designed to characterize Ca2+ homeostasis in platelets of essential hypertensives.


METHODS
A double-blind study was carried out. Untreated and treated (propranolol therapy) essential hypertensives were studied in comparison with normotensive control subjects. First-degree blood relatives of essential hypertensives were also studied. The various procedures used in the study were already standardized and well-established methods.


METHODS
For Ca2+ uptake and efflux studies, 45Ca was used. For intracellular free Ca2+ concentration studies the fluorescent Ca2+ chelator dye fura-2/acetoxymethyl ester (fura-2/AM) was used.


RESULTS
The uptake of 45Ca by unstimulated platelets of untreated essential hypertensives and their relatives was significantly higher than for controls. However, essential hypertensives treated with a beta-blocker drug showed no significant difference in Ca2+ uptake compared with controls. A significantly decreased Ca2+ efflux was observed in essential hypertensives (both untreated and treated) compared with controls. Relatives also showed a depressed Ca2+ efflux compared with controls.


CONCLUSIONS
It appears that the elevated intracellular free Ca2+ concentration levels in platelets (also observed by us) may be due to both an enhanced uptake into, and decreased efflux of Ca2+ from, the cell. Beta-blocker therapy may help to normalize the elevated intracellular free Ca2+ concentration levels observed in essential hypertensives. Relatives exhibit a state predisposed towards the development of hypertension.
Gulati
S
S
Department of Experimental Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
Khullar
M
M
Sagar
S
S
Ganguly
N K
NK
Sharma
B K
BK
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001792:Blood Platelets / Q000737:chemistry / Q000378:metabolism*; D002118:Calcium / Q000032:analysis*; D000252:Calcium-Transporting ATPases / Q000502:physiology*; D016022:Case-Control Studies; D004311:Double-Blind Method; D005190:Family; D006706:Homeostasis; D006801:Humans; D006973:Hypertension / Q000378:metabolism*; D008875:Middle Aged
D000252:Calcium-Transporting ATPases; D002118:Calcium