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Reduced cytosolic free Na+ concentration in intact platelets of essential hypertensives
1Medizinische Universität-Poliklinik, Münster, Germany.
Objective:
The role of intracellular Na+ concentration in the pathogenesis of essential hypertension is a point of considerable discussion.
Design:
Since the novel fluorescent dye technique offers the possibility of measuring cytosolic free Na+ concentration in intact living cells, the role of Na+ was reinvestigated in resting and stimulated human platelets.
Methods:
Cytosolic free Na+ concentration was measured in intact blood platelets of 20 essential hypertensive patients and 21 age- and sex-matched normotensive control subjects using the fluorescent dye Na(+)-binding benzofuran isophthalate.
Results:
Cytosolic free Na+ concentration was significantly reduced in hypertensives compared with normotensives. Inhibition of Na+,K(+)-adenosine triphosphatase by ouabain elevated cytosolic free Na+ concentration in hypertensives and normotensives in a similar way. Addition of thrombin increased cytosolic free Na+ concentration both in hypertensives and normotensives.
Conclusions:
Previous concepts concerning the role of Na+ in the pathogenesis of essential hypertension based upon measurements in destructed cells need to be reinvestigarted using new techniques in living cells.