Platelet alpha 2-adrenoceptor modifications induced by long-term treatment with indapamide in essential hypertension.
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 less than 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 less than 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 less than 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.
Carretta
R
R
Istituto di Patologia Medica and Pharmacology, Trieste's University, Italy.
Fabris
B
B
Fischetti
F
F
Muiesan
S
S
Bardelli
M
M
Melchior
C
C
Cesanelli
R
R
Pizzolitto
A
A
Giraldi
T
T
Greco
P L
PL
D000328:Adult; D001792:Blood Platelets / Q000032:analysis / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects; D004232:Diuretics / Q000627:therapeutic use*; D004311:Double-Blind Method; D004341:Drug Evaluation; D004837:Epinephrine / Q000097:blood; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000188:drug therapy*; D007190:Indapamide / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D011869:Radioligand Assay; D011897:Random Allocation; D011942:Receptors, Adrenergic, alpha / Q000032:analysis / Q000187:drug effects*; D013997:Time Factors
D004232:Diuretics; D011942:Receptors, Adrenergic, alpha; D007190:Indapamide; D009638:Norepinephrine; D004837:Epinephrine