Platelet alpha 2-adrenoceptor modifications induced by long-term treatment with indapamide in essential hypertension

Abstract

The effect of long-term treatment with indapamide in platelet alpha 2-adrenoceptors has been evaluated in 10 patients with essential hypertension, in a double-blind, cross-over study with placebo. After three months of therapy, indapamide significantly reduced mean blood pressure (from 137 ± 12 to 116 ± 6 mm Hg, p <0.001), whereas heart rate did not change (from 72 ± 8 to 73 ± 7 beats/minute). At the same time, platelet alpha 2-adrenoceptor number increased (from 168.2 ± 48.4 to 256.8 ± 14.5 fmol/mg protein, p <0.02), whereas the dissociation constant did not change (from 3.79 ± 2.9 to 4.97 ± 4.48). The plasma norepinephrine level was significantly reduced after long-term treatment with indapamide (from 275 ± 118 to 210 ± 56 pg/ml, p <0.02). These results bring about an inhibition of norepinephrine release from sympathetic nerve endings with a likely secondary increase of the number of platelet alpha 2-adrenoceptors.