Adrenoceptors on blood cells in patients with primary hypertension: correlation with blood pressure and related variables.

OBJECTIVE

Alterations in platelet alpha 2-adrenoceptor and mononuclear leucocyte beta 2-adrenoceptor characteristics in primary hypertension have been extensively studied. The results of the reports have not been consistent, possibly because of the small number of subjects in most of the studies. We therefore studied the blood-cell adrenoceptor characteristics in a relatively large group of primary hypertensive and normotensive subjects.

DESIGN

Platelet alpha 2-adrenoceptor characteristics were compared in 65 hypertensive and 51 normotensive subjects. Mononuclear leucocyte beta 2-adrenoceptor characteristics were compared in 72 hypertensives and 67 normotensives. Untreated hypertensive subjects were selected from the outpatient clinic and the normotensive controls were recruited by a newspaper announcement.

METHODS

Platelets and mononuclear leucocytes were isolated from blood samples obtained after at least 10 min supine rest. The alpha 2- and beta 2-adrenoceptor characteristics were determined with [3H]-rauwolscine and [125I]-(-1)cyanopindolol, respectively. Correlations between the adrenoceptor characteristics and clinical parameters of the subjects were studied.

RESULTS

No differences in alpha 2- or beta 2-adrenoceptor densities were observed between the two groups. However, a significantly lower equilibrium dissociation constant for [3H]-rauwolscine was observed in the hypertensive group. The correlations between the adrenoceptor characteristics and clinical parameters were weak and mostly not statistically significant. The results were compared with the most relevant studies in the literature.

CONCLUSIONS

From our study and the literature, we conclude that blood-cell adrenoceptor characteristics are unchanged in primary hypertension.