CYTOSOLIC FREE CALCIUM-CONCENTRATION IN PLATELETS IN PATIENTS WITH RENOVASCULAR HYPERTENSION AND PRIMARY ALDOSTERONISM

To investigate the role of cytosolic free calcium, [Ca2+]i, in seconda ry hypertension, the levels in platelets from 14 secondary hypertensiv es (7 renovascular hypertension, 7 primary aldosteronism) were compare d with those from 21 essential hypertensives and 15 normotensives by m eans of the fluorescent indicator, quin-2. The mean BP was significant ly higher in both the secondary hypertensives and essential hypertensi ves (122 +/- 8 and 124 +/- 12 mmHg) than in the normotensives (89 +/- 10 mmHg). Cytosolic free calcium in platelets was significantly higher in the essential hypertensives, but not in the secondary hypertensive s, compared with the normotensives (182 +/- 34, 141 +/- 17, 138 +/- 15 nM respectively). There was no significant difference in platelet [Ca 2+]i between renovascular hypertension and aldosteronism (142 +/- 19 v ersus 139 +/- 16 nM). There was no correlation between platelet [Ca2+] i and plasma renin activity, plasma aldosterone concentration or plasm a noradrenaline concentration in the three groups. Thus, the increase in platelet [Ca2+]i seen in essential hypertension was not found in pa tients with secondary hypertension. Our results suggest that the cytos olic calcium handling of secondary hypertensive patients with renal ar tery stenosis or primary aldosteronism differs from that of essential hypertensives.