Reduced cytosolic free Na+ concentration in intact platelets of essential hypertensives.

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.